From: Sultan Alsawaf sultan@kerneltoast.com
Hi,
This patchset contains fixes for two pesky i915 bugs that exist in 5.4.
The first bug, fixed by "drm/i915/gt: Schedule request retirement when timeline idles" upstream, is very high power consumption by i915 hardware due to an old commit that broke the RC6 power state for the iGPU on Skylake+. On my laptop, a Dell Precision 5540 with an i9-9880H, the idle power consumption of my laptop with this commit goes down from 10 W to 2 W, saving a massive 8 W of power. On other Skylake+ laptops I tested, this commit reduced idle power consumption by at least a few watts. The difference in power consumption can be observed by running `powertop` while disconnected from the charger, or by using the intel-undervolt tool [1] and running `intel-undervolt measure` which doesn't require being disconnected from the charger. The psys measurement from intel-undervolt is the one of interest.
Backporting this commit was not trivial due to i915's high rate of churn, but the backport didn't require changing any code from the original commit; it only required moving code around and not altering some #includes.
The second bug causes severe graphical corruption and flickering on laptops which support an esoteric power-saving mechanism called Panel Self Refresh (PSR). Enabled by default in 5.0, PSR causes graphical corruption to the point of unusability on many Dell laptops made within the past few years, since they typically support PSR. A bug was filed with Intel a while ago for this with more information [2]. I suspect most the community hasn't been affected by this bug because ThinkPads and many other laptops I checked didn't support PSR. As of writing, the issues I observed with PSR are fixed in Intel's drm-tip branch, but i915 suffers from so much churn that backporting the individual PSR fixes is infeasible (and an Intel engineer attested to this, saying that the PSR fixes in drm-tip wouldn't be backported [3]). Disabling PSR by default brings us back to pre-5.0 behavior, and from my tests with functional PSR in the drm-tip kernel, I didn't observe any reduction in power consumption with PSR enabled, so there isn't much lost from turning it off. Also, Ubuntu now ships with PSR disabled by default in its affected kernels, so there is distro support behind this change.
Thanks, Sultan
[1] https://github.com/kitsunyan/intel-undervolt [2] https://gitlab.freedesktop.org/drm/intel/issues/425 [3] https://gitlab.freedesktop.org/drm/intel/issues/425#note_416130
Chris Wilson (1): drm/i915/gt: Schedule request retirement when timeline idles
Sultan Alsawaf (1): drm/i915: Disable Panel Self Refresh (PSR) by default
drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + drivers/gpu/drm/i915/i915_params.c | 3 +- drivers/gpu/drm/i915/i915_params.h | 2 +- drivers/gpu/drm/i915/i915_request.c | 73 +++++++++++++++++++ drivers/gpu/drm/i915/i915_request.h | 4 + 9 files changed, 101 insertions(+), 3 deletions(-)
From: Sultan Alsawaf sultan@kerneltoast.com
On all Dell laptops with panels and chipsets that support PSR (an esoteric power-saving mechanism), both PSR1 and PSR2 cause flickering and graphical glitches, sometimes to the point of making the laptop unusable. Many laptops don't support PSR so it isn't known if PSR works correctly on any consumer hardware as of 5.4. PSR was enabled by default in 5.0 for capable hardware, so this patch just restores the previous functionality of PSR being disabled by default.
More info is available on the freedesktop bug: https://gitlab.freedesktop.org/drm/intel/issues/425
Cc: stable@vger.kernel.org # 5.4.x Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com --- drivers/gpu/drm/i915/i915_params.c | 3 +-- drivers/gpu/drm/i915/i915_params.h | 2 +- 2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c index 296452f9efe4..4a0d37f7cf49 100644 --- a/drivers/gpu/drm/i915/i915_params.c +++ b/drivers/gpu/drm/i915/i915_params.c @@ -84,8 +84,7 @@ i915_param_named_unsafe(enable_hangcheck, bool, 0600,
i915_param_named_unsafe(enable_psr, int, 0600, "Enable PSR " - "(0=disabled, 1=enabled) " - "Default: -1 (use per-chip default)"); + "(-1=use per-chip default, 0=disabled [default], 1=enabled) ");
i915_param_named_unsafe(force_probe, charp, 0400, "Force probe the driver for specified devices. " diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h index d29ade3b7de6..715888811593 100644 --- a/drivers/gpu/drm/i915/i915_params.h +++ b/drivers/gpu/drm/i915/i915_params.h @@ -50,7 +50,7 @@ struct drm_printer; param(int, vbt_sdvo_panel_type, -1) \ param(int, enable_dc, -1) \ param(int, enable_fbc, -1) \ - param(int, enable_psr, -1) \ + param(int, enable_psr, 0) \ param(int, disable_power_well, -1) \ param(int, enable_ips, 1) \ param(int, invert_brightness, 0) \
From: Chris Wilson chris@chris-wilson.co.uk
commit 311770173fac27845a3a83e2c16100a54d308f72 upstream.
The major drawback of commit 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") is that it disables RC6 while Skylake (and friends) is active, and we do not consider the GPU idle until all outstanding requests have been retired and the engine switched over to the kernel context. If userspace is idle, this task falls onto our background idle worker, which only runs roughly once a second, meaning that userspace has to have been idle for a couple of seconds before we enable RC6 again. Naturally, this causes us to consume considerably more energy than before as powersaving is effectively disabled while a display server (here's looking at you Xorg) is running.
As execlists will get a completion event as each context is completed, we can use this interrupt to queue a retire worker bound to this engine to cleanup idle timelines. We will then immediately notice the idle engine (without userspace intervention or the aid of the background retire worker) and start parking the GPU. Thus during light workloads, we will do much more work to idle the GPU faster... Hopefully with commensurate power saving!
v2: Watch context completions and only look at those local to the engine when retiring to reduce the amount of excess work we perform.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 References: 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") References: 2248a28384fe ("drm/i915/gen8+: Add RC6 CTX corruption WA") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris... (cherry picked from commit 4f88f8747fa43c97c3b3712d8d87295ea757cc51) Signed-off-by: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: stable@vger.kernel.org # 5.4.x Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com --- drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + drivers/gpu/drm/i915/i915_request.c | 73 +++++++++++++++++++ drivers/gpu/drm/i915/i915_request.h | 4 + 7 files changed, 99 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 4ce8626b140e..f732a2177cd0 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -600,6 +600,7 @@ static int intel_engine_setup_common(struct intel_engine_cs *engine) intel_engine_init_hangcheck(engine); intel_engine_init_cmd_parser(engine); intel_engine_init__pm(engine); + intel_engine_init_retire(engine);
intel_engine_pool_init(&engine->pool);
@@ -807,6 +808,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine)
cleanup_status_page(engine);
+ intel_engine_fini_retire(engine); intel_engine_pool_fini(&engine->pool); intel_engine_fini_breadcrumbs(engine); intel_engine_cleanup_cmd_parser(engine); diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index c77c9518c58b..1eb7189f88e1 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -471,6 +471,14 @@ struct intel_engine_cs {
struct intel_engine_execlists execlists;
+ /* + * Keep track of completed timelines on this engine for early + * retirement with the goal of quickly enabling powersaving as + * soon as the engine is idle. + */ + struct intel_timeline *retire; + struct work_struct retire_work; + /* status_notifier: list of callbacks for context-switch changes */ struct atomic_notifier_head context_status_notifier;
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 66f6d1a897f2..a1538c8f7922 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -606,6 +606,14 @@ __execlists_schedule_out(struct i915_request *rq, { struct intel_context * const ce = rq->hw_context;
+ /* + * If we have just completed this context, the engine may now be + * idle and we want to re-enter powersaving. + */ + if (list_is_last(&rq->link, &ce->timeline->requests) && + i915_request_completed(rq)) + intel_engine_add_retire(engine, ce->timeline); + intel_engine_context_out(engine); execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT); intel_gt_pm_put(engine->gt); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c index 9cb01d9828f1..63515e3caaf2 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline.c +++ b/drivers/gpu/drm/i915/gt/intel_timeline.c @@ -282,6 +282,7 @@ void intel_timeline_fini(struct intel_timeline *timeline) { GEM_BUG_ON(atomic_read(&timeline->pin_count)); GEM_BUG_ON(!list_empty(&timeline->requests)); + GEM_BUG_ON(timeline->retire);
if (timeline->hwsp_cacheline) cacheline_free(timeline->hwsp_cacheline); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline_types.h b/drivers/gpu/drm/i915/gt/intel_timeline_types.h index 2b1baf2fcc8e..adf2d14ef647 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline_types.h +++ b/drivers/gpu/drm/i915/gt/intel_timeline_types.h @@ -65,6 +65,9 @@ struct intel_timeline { */ struct i915_active_request last_request;
+ /** A chain of completed timelines ready for early retirement. */ + struct intel_timeline *retire; + /** * We track the most recent seqno that we wait on in every context so * that we only have to emit a new await and dependency on a more diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 0d39038898d4..4d59cfca9eae 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -600,6 +600,79 @@ static void retire_requests(struct intel_timeline *tl) break; }
+static void engine_retire(struct work_struct *work) +{ + struct intel_engine_cs *engine = + container_of(work, typeof(*engine), retire_work); + struct intel_timeline *tl = xchg(&engine->retire, NULL); + + do { + struct intel_timeline *next = xchg(&tl->retire, NULL); + + /* + * Our goal here is to retire _idle_ timelines as soon as + * possible (as they are idle, we do not expect userspace + * to be cleaning up anytime soon). + * + * If the timeline is currently locked, either it is being + * retired elsewhere or about to be! + */ + if (mutex_trylock(&tl->mutex)) { + retire_requests(tl); + mutex_unlock(&tl->mutex); + } + intel_timeline_put(tl); + + GEM_BUG_ON(!next); + tl = ptr_mask_bits(next, 1); + } while (tl); +} + +static bool add_retire(struct intel_engine_cs *engine, + struct intel_timeline *tl) +{ + struct intel_timeline *first; + + /* + * We open-code a llist here to include the additional tag [BIT(0)] + * so that we know when the timeline is already on a + * retirement queue: either this engine or another. + * + * However, we rely on that a timeline can only be active on a single + * engine at any one time and that add_retire() is called before the + * engine releases the timeline and transferred to another to retire. + */ + + if (READ_ONCE(tl->retire)) /* already queued */ + return false; + + intel_timeline_get(tl); + first = READ_ONCE(engine->retire); + do + tl->retire = ptr_pack_bits(first, 1, 1); + while (!try_cmpxchg(&engine->retire, &first, tl)); + + return !first; +} + +void intel_engine_add_retire(struct intel_engine_cs *engine, + struct intel_timeline *tl) +{ + if (add_retire(engine, tl)) + schedule_work(&engine->retire_work); +} + +void intel_engine_init_retire(struct intel_engine_cs *engine) +{ + INIT_WORK(&engine->retire_work, engine_retire); +} + +void intel_engine_fini_retire(struct intel_engine_cs *engine) +{ + flush_work(&engine->retire_work); + GEM_BUG_ON(engine->retire); +} + static noinline struct i915_request * request_alloc_slow(struct intel_timeline *tl, gfp_t gfp) { diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 3a3e7bbf19ff..40caa2f3f4a4 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -445,5 +445,9 @@ static inline bool i915_request_has_nopreempt(const struct i915_request *rq) }
bool i915_retire_requests(struct drm_i915_private *i915); +void intel_engine_init_retire(struct intel_engine_cs *engine); +void intel_engine_add_retire(struct intel_engine_cs *engine, + struct intel_timeline *tl); +void intel_engine_fini_retire(struct intel_engine_cs *engine);
#endif /* I915_REQUEST_H */
On Sun, Mar 29, 2020 at 08:30:56PM -0700, Sultan Alsawaf wrote:
From: Sultan Alsawaf sultan@kerneltoast.com
On all Dell laptops with panels and chipsets that support PSR (an esoteric power-saving mechanism), both PSR1 and PSR2 cause flickering and graphical glitches, sometimes to the point of making the laptop unusable. Many laptops don't support PSR so it isn't known if PSR works correctly on any consumer hardware as of 5.4. PSR was enabled by default in 5.0 for capable hardware, so this patch just restores the previous functionality of PSR being disabled by default.
More info is available on the freedesktop bug: https://gitlab.freedesktop.org/drm/intel/issues/425
Cc: stable@vger.kernel.org # 5.4.x Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com
drivers/gpu/drm/i915/i915_params.c | 3 +-- drivers/gpu/drm/i915/i915_params.h | 2 +- 2 files changed, 2 insertions(+), 3 deletions(-)
What is the git commit id of this patch in Linus's tree?
thanks,
greg k-h
On Sun, Mar 29, 2020 at 08:30:55PM -0700, Sultan Alsawaf wrote:
From: Sultan Alsawaf sultan@kerneltoast.com
Hi,
This patchset contains fixes for two pesky i915 bugs that exist in 5.4.
Any reason you didn't also cc: the developers involved in these patches, and maintainers?
Please resend and do that.
thanks,
greg k-h
On Mon, Mar 30, 2020 at 10:51:04AM +0200, Greg KH wrote:
On Sun, Mar 29, 2020 at 08:30:56PM -0700, Sultan Alsawaf wrote:
From: Sultan Alsawaf sultan@kerneltoast.com
On all Dell laptops with panels and chipsets that support PSR (an esoteric power-saving mechanism), both PSR1 and PSR2 cause flickering and graphical glitches, sometimes to the point of making the laptop unusable. Many laptops don't support PSR so it isn't known if PSR works correctly on any consumer hardware as of 5.4. PSR was enabled by default in 5.0 for capable hardware, so this patch just restores the previous functionality of PSR being disabled by default.
More info is available on the freedesktop bug: https://gitlab.freedesktop.org/drm/intel/issues/425
Cc: stable@vger.kernel.org # 5.4.x Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com
drivers/gpu/drm/i915/i915_params.c | 3 +-- drivers/gpu/drm/i915/i915_params.h | 2 +- 2 files changed, 2 insertions(+), 3 deletions(-)
What is the git commit id of this patch in Linus's tree?
thanks,
greg k-h
This isn't in Linus' tree. I know for a fact that 5.4 has broken PSR support that'll never be fixed, but I wasn't sure if PSR was still broken in 5.6.
However, I tested 5.6 for a bit right now and PSR is still broken. And to top it off, I managed to reproduce some PSR glitches with the drm-tip branch, so there's currently no kernel in existence with functional PSR. :)
I will send this patch for inclusion in Linus' tree, so please disregard it for now.
Thanks, Sultan
CC'ing relevant folks. My apologies.
Sultan
Quoting Sultan Alsawaf (2020-03-30 04:30:57)
+static void engine_retire(struct work_struct *work) +{
struct intel_engine_cs *engine =container_of(work, typeof(*engine), retire_work);struct intel_timeline *tl = xchg(&engine->retire, NULL);do {struct intel_timeline *next = xchg(&tl->retire, NULL);/** Our goal here is to retire _idle_ timelines as soon as* possible (as they are idle, we do not expect userspace* to be cleaning up anytime soon).** If the timeline is currently locked, either it is being* retired elsewhere or about to be!*/
iirc the backport requires the retirement to be wrapped in struct_mutex
mutex_lock(&engine->i915->drm.struct_mutex);
if (mutex_trylock(&tl->mutex)) {retire_requests(tl);mutex_unlock(&tl->mutex);}
mutex_unlock(&engine->i915->drm.struct_mutex);
Now the question is whether that was for 5.3 or 5.4. I think 5.3 is where the changes were more severe and where we switch to the 4.19 approach.
intel_timeline_put(tl);GEM_BUG_ON(!next);tl = ptr_mask_bits(next, 1);} while (tl);+}
On Mon, Mar 30, 2020 at 05:27:28PM +0100, Chris Wilson wrote:
Quoting Sultan Alsawaf (2020-03-30 04:30:57)
+static void engine_retire(struct work_struct *work) +{
struct intel_engine_cs *engine =container_of(work, typeof(*engine), retire_work);struct intel_timeline *tl = xchg(&engine->retire, NULL);do {struct intel_timeline *next = xchg(&tl->retire, NULL);/** Our goal here is to retire _idle_ timelines as soon as* possible (as they are idle, we do not expect userspace* to be cleaning up anytime soon).** If the timeline is currently locked, either it is being* retired elsewhere or about to be!*/iirc the backport requires the retirement to be wrapped in struct_mutex
mutex_lock(&engine->i915->drm.struct_mutex);
if (mutex_trylock(&tl->mutex)) {retire_requests(tl);mutex_unlock(&tl->mutex);}mutex_unlock(&engine->i915->drm.struct_mutex);
Now the question is whether that was for 5.3 or 5.4. I think 5.3 is where the changes were more severe and where we switch to the 4.19 approach.
intel_timeline_put(tl);GEM_BUG_ON(!next);tl = ptr_mask_bits(next, 1);} while (tl);+}
In 5.4, the existing retirement instances don't hold `&engine->i915->drm.struct_mutex`, however it is held in 5.3. So it looks like this is fine as-is for 5.4.
Sultan
Quoting Sultan Alsawaf (2020-03-30 17:35:14)
On Mon, Mar 30, 2020 at 05:27:28PM +0100, Chris Wilson wrote:
Quoting Sultan Alsawaf (2020-03-30 04:30:57)
+static void engine_retire(struct work_struct *work) +{
struct intel_engine_cs *engine =container_of(work, typeof(*engine), retire_work);struct intel_timeline *tl = xchg(&engine->retire, NULL);do {struct intel_timeline *next = xchg(&tl->retire, NULL);/** Our goal here is to retire _idle_ timelines as soon as* possible (as they are idle, we do not expect userspace* to be cleaning up anytime soon).** If the timeline is currently locked, either it is being* retired elsewhere or about to be!*/iirc the backport requires the retirement to be wrapped in struct_mutex
mutex_lock(&engine->i915->drm.struct_mutex);
if (mutex_trylock(&tl->mutex)) {retire_requests(tl);mutex_unlock(&tl->mutex);}mutex_unlock(&engine->i915->drm.struct_mutex);
Now the question is whether that was for 5.3 or 5.4. I think 5.3 is where the changes were more severe and where we switch to the 4.19 approach.
intel_timeline_put(tl);GEM_BUG_ON(!next);tl = ptr_mask_bits(next, 1);} while (tl);+}
In 5.4, the existing retirement instances don't hold `&engine->i915->drm.struct_mutex`, however it is held in 5.3. So it looks like this is fine as-is for 5.4.
git agrees.
commit e5dadff4b09376e8ed92ecc0c12f1b9b3b1fbd19 Author: Chris Wilson chris@chris-wilson.co.uk Date: Thu Aug 15 21:57:09 2019 +0100
drm/i915: Protect request retirement with timeline->mutex
is in v5.4, so we should be safe to retire without the struct_mutex. -Chris
On Mon, Mar 30, 2020 at 05:45:25PM +0100, Chris Wilson wrote:
Quoting Sultan Alsawaf (2020-03-30 17:35:14)
On Mon, Mar 30, 2020 at 05:27:28PM +0100, Chris Wilson wrote:
Quoting Sultan Alsawaf (2020-03-30 04:30:57)
+static void engine_retire(struct work_struct *work) +{
struct intel_engine_cs *engine =container_of(work, typeof(*engine), retire_work);struct intel_timeline *tl = xchg(&engine->retire, NULL);do {struct intel_timeline *next = xchg(&tl->retire, NULL);/** Our goal here is to retire _idle_ timelines as soon as* possible (as they are idle, we do not expect userspace* to be cleaning up anytime soon).** If the timeline is currently locked, either it is being* retired elsewhere or about to be!*/iirc the backport requires the retirement to be wrapped in struct_mutex
mutex_lock(&engine->i915->drm.struct_mutex);
if (mutex_trylock(&tl->mutex)) {retire_requests(tl);mutex_unlock(&tl->mutex);}mutex_unlock(&engine->i915->drm.struct_mutex);
Now the question is whether that was for 5.3 or 5.4. I think 5.3 is where the changes were more severe and where we switch to the 4.19 approach.
intel_timeline_put(tl);GEM_BUG_ON(!next);tl = ptr_mask_bits(next, 1);} while (tl);+}
In 5.4, the existing retirement instances don't hold `&engine->i915->drm.struct_mutex`, however it is held in 5.3. So it looks like this is fine as-is for 5.4.
git agrees.
commit e5dadff4b09376e8ed92ecc0c12f1b9b3b1fbd19 Author: Chris Wilson chris@chris-wilson.co.uk Date: Thu Aug 15 21:57:09 2019 +0100
drm/i915: Protect request retirement with timeline->mutexis in v5.4, so we should be safe to retire without the struct_mutex. -Chris
No, you were right; `&engine->i915->drm.struct_mutex` needs to be held in 5.4, otherwise retirement races with vma destruction. I'll send an updated patch.
Sultan
From: Chris Wilson chris@chris-wilson.co.uk
The major drawback of commit 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") is that it disables RC6 while Skylake (and friends) is active, and we do not consider the GPU idle until all outstanding requests have been retired and the engine switched over to the kernel context. If userspace is idle, this task falls onto our background idle worker, which only runs roughly once a second, meaning that userspace has to have been idle for a couple of seconds before we enable RC6 again. Naturally, this causes us to consume considerably more energy than before as powersaving is effectively disabled while a display server (here's looking at you Xorg) is running.
As execlists will get a completion event as each context is completed, we can use this interrupt to queue a retire worker bound to this engine to cleanup idle timelines. We will then immediately notice the idle engine (without userspace intervention or the aid of the background retire worker) and start parking the GPU. Thus during light workloads, we will do much more work to idle the GPU faster... Hopefully with commensurate power saving!
v2: Watch context completions and only look at those local to the engine when retiring to reduce the amount of excess work we perform.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 References: 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") References: 2248a28384fe ("drm/i915/gen8+: Add RC6 CTX corruption WA") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris... (cherry picked from commit 4f88f8747fa43c97c3b3712d8d87295ea757cc51)
For the backport to 5.4, struct_mutex needs to be held while retiring so that retirement doesn't race with vma destruction. Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com --- drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + drivers/gpu/drm/i915/i915_request.c | 75 +++++++++++++++++++ drivers/gpu/drm/i915/i915_request.h | 4 + 7 files changed, 101 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 4ce8626b140e..f732a2177cd0 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -600,6 +600,7 @@ static int intel_engine_setup_common(struct intel_engine_cs *engine) intel_engine_init_hangcheck(engine); intel_engine_init_cmd_parser(engine); intel_engine_init__pm(engine); + intel_engine_init_retire(engine);
intel_engine_pool_init(&engine->pool);
@@ -807,6 +808,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine)
cleanup_status_page(engine);
+ intel_engine_fini_retire(engine); intel_engine_pool_fini(&engine->pool); intel_engine_fini_breadcrumbs(engine); intel_engine_cleanup_cmd_parser(engine); diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index c77c9518c58b..1eb7189f88e1 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -471,6 +471,14 @@ struct intel_engine_cs {
struct intel_engine_execlists execlists;
+ /* + * Keep track of completed timelines on this engine for early + * retirement with the goal of quickly enabling powersaving as + * soon as the engine is idle. + */ + struct intel_timeline *retire; + struct work_struct retire_work; + /* status_notifier: list of callbacks for context-switch changes */ struct atomic_notifier_head context_status_notifier;
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 66f6d1a897f2..a1538c8f7922 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -606,6 +606,14 @@ __execlists_schedule_out(struct i915_request *rq, { struct intel_context * const ce = rq->hw_context;
+ /* + * If we have just completed this context, the engine may now be + * idle and we want to re-enter powersaving. + */ + if (list_is_last(&rq->link, &ce->timeline->requests) && + i915_request_completed(rq)) + intel_engine_add_retire(engine, ce->timeline); + intel_engine_context_out(engine); execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT); intel_gt_pm_put(engine->gt); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c index 9cb01d9828f1..63515e3caaf2 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline.c +++ b/drivers/gpu/drm/i915/gt/intel_timeline.c @@ -282,6 +282,7 @@ void intel_timeline_fini(struct intel_timeline *timeline) { GEM_BUG_ON(atomic_read(&timeline->pin_count)); GEM_BUG_ON(!list_empty(&timeline->requests)); + GEM_BUG_ON(timeline->retire);
if (timeline->hwsp_cacheline) cacheline_free(timeline->hwsp_cacheline); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline_types.h b/drivers/gpu/drm/i915/gt/intel_timeline_types.h index 2b1baf2fcc8e..adf2d14ef647 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline_types.h +++ b/drivers/gpu/drm/i915/gt/intel_timeline_types.h @@ -65,6 +65,9 @@ struct intel_timeline { */ struct i915_active_request last_request;
+ /** A chain of completed timelines ready for early retirement. */ + struct intel_timeline *retire; + /** * We track the most recent seqno that we wait on in every context so * that we only have to emit a new await and dependency on a more diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 0d39038898d4..35457fda350c 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -600,6 +600,81 @@ static void retire_requests(struct intel_timeline *tl) break; }
+static void engine_retire(struct work_struct *work) +{ + struct intel_engine_cs *engine = + container_of(work, typeof(*engine), retire_work); + struct intel_timeline *tl = xchg(&engine->retire, NULL); + + do { + struct intel_timeline *next = xchg(&tl->retire, NULL); + + /* + * Our goal here is to retire _idle_ timelines as soon as + * possible (as they are idle, we do not expect userspace + * to be cleaning up anytime soon). + * + * If the timeline is currently locked, either it is being + * retired elsewhere or about to be! + */ + mutex_lock(&engine->i915->drm.struct_mutex); + if (mutex_trylock(&tl->mutex)) { + retire_requests(tl); + mutex_unlock(&tl->mutex); + } + mutex_unlock(&engine->i915->drm.struct_mutex); + intel_timeline_put(tl); + + GEM_BUG_ON(!next); + tl = ptr_mask_bits(next, 1); + } while (tl); +} + +static bool add_retire(struct intel_engine_cs *engine, + struct intel_timeline *tl) +{ + struct intel_timeline *first; + + /* + * We open-code a llist here to include the additional tag [BIT(0)] + * so that we know when the timeline is already on a + * retirement queue: either this engine or another. + * + * However, we rely on that a timeline can only be active on a single + * engine at any one time and that add_retire() is called before the + * engine releases the timeline and transferred to another to retire. + */ + + if (READ_ONCE(tl->retire)) /* already queued */ + return false; + + intel_timeline_get(tl); + first = READ_ONCE(engine->retire); + do + tl->retire = ptr_pack_bits(first, 1, 1); + while (!try_cmpxchg(&engine->retire, &first, tl)); + + return !first; +} + +void intel_engine_add_retire(struct intel_engine_cs *engine, + struct intel_timeline *tl) +{ + if (add_retire(engine, tl)) + schedule_work(&engine->retire_work); +} + +void intel_engine_init_retire(struct intel_engine_cs *engine) +{ + INIT_WORK(&engine->retire_work, engine_retire); +} + +void intel_engine_fini_retire(struct intel_engine_cs *engine) +{ + flush_work(&engine->retire_work); + GEM_BUG_ON(engine->retire); +} + static noinline struct i915_request * request_alloc_slow(struct intel_timeline *tl, gfp_t gfp) { diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 3a3e7bbf19ff..40caa2f3f4a4 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -445,5 +445,9 @@ static inline bool i915_request_has_nopreempt(const struct i915_request *rq) }
bool i915_retire_requests(struct drm_i915_private *i915); +void intel_engine_init_retire(struct intel_engine_cs *engine); +void intel_engine_add_retire(struct intel_engine_cs *engine, + struct intel_timeline *tl); +void intel_engine_fini_retire(struct intel_engine_cs *engine);
#endif /* I915_REQUEST_H */
On Tue, Apr 07, 2020 at 01:43:45PM -0700, Sultan Alsawaf wrote:
From: Chris Wilson chris@chris-wilson.co.uk
The major drawback of commit 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") is that it disables RC6 while Skylake (and friends) is active, and we do not consider the GPU idle until all outstanding requests have been retired and the engine switched over to the kernel context. If userspace is idle, this task falls onto our background idle worker, which only runs roughly once a second, meaning that userspace has to have been idle for a couple of seconds before we enable RC6 again. Naturally, this causes us to consume considerably more energy than before as powersaving is effectively disabled while a display server (here's looking at you Xorg) is running.
As execlists will get a completion event as each context is completed, we can use this interrupt to queue a retire worker bound to this engine to cleanup idle timelines. We will then immediately notice the idle engine (without userspace intervention or the aid of the background retire worker) and start parking the GPU. Thus during light workloads, we will do much more work to idle the GPU faster... Hopefully with commensurate power saving!
v2: Watch context completions and only look at those local to the engine when retiring to reduce the amount of excess work we perform.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 References: 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") References: 2248a28384fe ("drm/i915/gen8+: Add RC6 CTX corruption WA") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris... (cherry picked from commit 4f88f8747fa43c97c3b3712d8d87295ea757cc51)
For the backport to 5.4, struct_mutex needs to be held while retiring so that retirement doesn't race with vma destruction. Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com
drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + drivers/gpu/drm/i915/i915_request.c | 75 +++++++++++++++++++ drivers/gpu/drm/i915/i915_request.h | 4 + 7 files changed, 101 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 4ce8626b140e..f732a2177cd0 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -600,6 +600,7 @@ static int intel_engine_setup_common(struct intel_engine_cs *engine) intel_engine_init_hangcheck(engine); intel_engine_init_cmd_parser(engine); intel_engine_init__pm(engine);
- intel_engine_init_retire(engine);
intel_engine_pool_init(&engine->pool); @@ -807,6 +808,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine) cleanup_status_page(engine);
- intel_engine_fini_retire(engine); intel_engine_pool_fini(&engine->pool); intel_engine_fini_breadcrumbs(engine); intel_engine_cleanup_cmd_parser(engine);
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index c77c9518c58b..1eb7189f88e1 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -471,6 +471,14 @@ struct intel_engine_cs { struct intel_engine_execlists execlists;
- /*
* Keep track of completed timelines on this engine for early* retirement with the goal of quickly enabling powersaving as* soon as the engine is idle.*/- struct intel_timeline *retire;
- struct work_struct retire_work;
- /* status_notifier: list of callbacks for context-switch changes */ struct atomic_notifier_head context_status_notifier;
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 66f6d1a897f2..a1538c8f7922 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -606,6 +606,14 @@ __execlists_schedule_out(struct i915_request *rq, { struct intel_context * const ce = rq->hw_context;
- /*
* If we have just completed this context, the engine may now be* idle and we want to re-enter powersaving.*/- if (list_is_last(&rq->link, &ce->timeline->requests) &&
i915_request_completed(rq))intel_engine_add_retire(engine, ce->timeline);- intel_engine_context_out(engine); execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT); intel_gt_pm_put(engine->gt);
diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c index 9cb01d9828f1..63515e3caaf2 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline.c +++ b/drivers/gpu/drm/i915/gt/intel_timeline.c @@ -282,6 +282,7 @@ void intel_timeline_fini(struct intel_timeline *timeline) { GEM_BUG_ON(atomic_read(&timeline->pin_count)); GEM_BUG_ON(!list_empty(&timeline->requests));
- GEM_BUG_ON(timeline->retire);
if (timeline->hwsp_cacheline) cacheline_free(timeline->hwsp_cacheline); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline_types.h b/drivers/gpu/drm/i915/gt/intel_timeline_types.h index 2b1baf2fcc8e..adf2d14ef647 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline_types.h +++ b/drivers/gpu/drm/i915/gt/intel_timeline_types.h @@ -65,6 +65,9 @@ struct intel_timeline { */ struct i915_active_request last_request;
- /** A chain of completed timelines ready for early retirement. */
- struct intel_timeline *retire;
- /**
- We track the most recent seqno that we wait on in every context so
- that we only have to emit a new await and dependency on a more
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 0d39038898d4..35457fda350c 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -600,6 +600,81 @@ static void retire_requests(struct intel_timeline *tl) break; } +static void engine_retire(struct work_struct *work) +{
- struct intel_engine_cs *engine =
container_of(work, typeof(*engine), retire_work);- struct intel_timeline *tl = xchg(&engine->retire, NULL);
- do {
struct intel_timeline *next = xchg(&tl->retire, NULL);/** Our goal here is to retire _idle_ timelines as soon as* possible (as they are idle, we do not expect userspace* to be cleaning up anytime soon).** If the timeline is currently locked, either it is being* retired elsewhere or about to be!*/mutex_lock(&engine->i915->drm.struct_mutex);if (mutex_trylock(&tl->mutex)) {retire_requests(tl);mutex_unlock(&tl->mutex);}mutex_unlock(&engine->i915->drm.struct_mutex);intel_timeline_put(tl);GEM_BUG_ON(!next);tl = ptr_mask_bits(next, 1);- } while (tl);
+}
+static bool add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl)+{
- struct intel_timeline *first;
- /*
* We open-code a llist here to include the additional tag [BIT(0)]* so that we know when the timeline is already on a* retirement queue: either this engine or another.** However, we rely on that a timeline can only be active on a single* engine at any one time and that add_retire() is called before the* engine releases the timeline and transferred to another to retire.*/- if (READ_ONCE(tl->retire)) /* already queued */
return false;- intel_timeline_get(tl);
- first = READ_ONCE(engine->retire);
- do
tl->retire = ptr_pack_bits(first, 1, 1);- while (!try_cmpxchg(&engine->retire, &first, tl));
- return !first;
+}
+void intel_engine_add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl)+{
- if (add_retire(engine, tl))
schedule_work(&engine->retire_work);+}
+void intel_engine_init_retire(struct intel_engine_cs *engine) +{
- INIT_WORK(&engine->retire_work, engine_retire);
+}
+void intel_engine_fini_retire(struct intel_engine_cs *engine) +{
- flush_work(&engine->retire_work);
- GEM_BUG_ON(engine->retire);
+}
static noinline struct i915_request * request_alloc_slow(struct intel_timeline *tl, gfp_t gfp) { diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 3a3e7bbf19ff..40caa2f3f4a4 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -445,5 +445,9 @@ static inline bool i915_request_has_nopreempt(const struct i915_request *rq) } bool i915_retire_requests(struct drm_i915_private *i915); +void intel_engine_init_retire(struct intel_engine_cs *engine); +void intel_engine_add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl);+void intel_engine_fini_retire(struct intel_engine_cs *engine);
#endif /* I915_REQUEST_H */
2.26.0
Hi Greg,
Could you queue this one up as well?
Thanks, Sultan
On Sun, Apr 12, 2020 at 12:48:51AM -0700, Sultan Alsawaf wrote:
On Tue, Apr 07, 2020 at 01:43:45PM -0700, Sultan Alsawaf wrote:
From: Chris Wilson chris@chris-wilson.co.uk
The major drawback of commit 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") is that it disables RC6 while Skylake (and friends) is active, and we do not consider the GPU idle until all outstanding requests have been retired and the engine switched over to the kernel context. If userspace is idle, this task falls onto our background idle worker, which only runs roughly once a second, meaning that userspace has to have been idle for a couple of seconds before we enable RC6 again. Naturally, this causes us to consume considerably more energy than before as powersaving is effectively disabled while a display server (here's looking at you Xorg) is running.
As execlists will get a completion event as each context is completed, we can use this interrupt to queue a retire worker bound to this engine to cleanup idle timelines. We will then immediately notice the idle engine (without userspace intervention or the aid of the background retire worker) and start parking the GPU. Thus during light workloads, we will do much more work to idle the GPU faster... Hopefully with commensurate power saving!
v2: Watch context completions and only look at those local to the engine when retiring to reduce the amount of excess work we perform.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 References: 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") References: 2248a28384fe ("drm/i915/gen8+: Add RC6 CTX corruption WA") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris... (cherry picked from commit 4f88f8747fa43c97c3b3712d8d87295ea757cc51)
For the backport to 5.4, struct_mutex needs to be held while retiring so that retirement doesn't race with vma destruction. Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com
drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + drivers/gpu/drm/i915/i915_request.c | 75 +++++++++++++++++++ drivers/gpu/drm/i915/i915_request.h | 4 + 7 files changed, 101 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 4ce8626b140e..f732a2177cd0 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -600,6 +600,7 @@ static int intel_engine_setup_common(struct intel_engine_cs *engine) intel_engine_init_hangcheck(engine); intel_engine_init_cmd_parser(engine); intel_engine_init__pm(engine);
- intel_engine_init_retire(engine);
intel_engine_pool_init(&engine->pool); @@ -807,6 +808,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine) cleanup_status_page(engine);
- intel_engine_fini_retire(engine); intel_engine_pool_fini(&engine->pool); intel_engine_fini_breadcrumbs(engine); intel_engine_cleanup_cmd_parser(engine);
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index c77c9518c58b..1eb7189f88e1 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -471,6 +471,14 @@ struct intel_engine_cs { struct intel_engine_execlists execlists;
- /*
* Keep track of completed timelines on this engine for early* retirement with the goal of quickly enabling powersaving as* soon as the engine is idle.*/- struct intel_timeline *retire;
- struct work_struct retire_work;
- /* status_notifier: list of callbacks for context-switch changes */ struct atomic_notifier_head context_status_notifier;
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 66f6d1a897f2..a1538c8f7922 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -606,6 +606,14 @@ __execlists_schedule_out(struct i915_request *rq, { struct intel_context * const ce = rq->hw_context;
- /*
* If we have just completed this context, the engine may now be* idle and we want to re-enter powersaving.*/- if (list_is_last(&rq->link, &ce->timeline->requests) &&
i915_request_completed(rq))intel_engine_add_retire(engine, ce->timeline);- intel_engine_context_out(engine); execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT); intel_gt_pm_put(engine->gt);
diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c index 9cb01d9828f1..63515e3caaf2 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline.c +++ b/drivers/gpu/drm/i915/gt/intel_timeline.c @@ -282,6 +282,7 @@ void intel_timeline_fini(struct intel_timeline *timeline) { GEM_BUG_ON(atomic_read(&timeline->pin_count)); GEM_BUG_ON(!list_empty(&timeline->requests));
- GEM_BUG_ON(timeline->retire);
if (timeline->hwsp_cacheline) cacheline_free(timeline->hwsp_cacheline); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline_types.h b/drivers/gpu/drm/i915/gt/intel_timeline_types.h index 2b1baf2fcc8e..adf2d14ef647 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline_types.h +++ b/drivers/gpu/drm/i915/gt/intel_timeline_types.h @@ -65,6 +65,9 @@ struct intel_timeline { */ struct i915_active_request last_request;
- /** A chain of completed timelines ready for early retirement. */
- struct intel_timeline *retire;
- /**
- We track the most recent seqno that we wait on in every context so
- that we only have to emit a new await and dependency on a more
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 0d39038898d4..35457fda350c 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -600,6 +600,81 @@ static void retire_requests(struct intel_timeline *tl) break; } +static void engine_retire(struct work_struct *work) +{
- struct intel_engine_cs *engine =
container_of(work, typeof(*engine), retire_work);- struct intel_timeline *tl = xchg(&engine->retire, NULL);
- do {
struct intel_timeline *next = xchg(&tl->retire, NULL);/** Our goal here is to retire _idle_ timelines as soon as* possible (as they are idle, we do not expect userspace* to be cleaning up anytime soon).** If the timeline is currently locked, either it is being* retired elsewhere or about to be!*/mutex_lock(&engine->i915->drm.struct_mutex);if (mutex_trylock(&tl->mutex)) {retire_requests(tl);mutex_unlock(&tl->mutex);}mutex_unlock(&engine->i915->drm.struct_mutex);intel_timeline_put(tl);GEM_BUG_ON(!next);tl = ptr_mask_bits(next, 1);- } while (tl);
+}
+static bool add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl)+{
- struct intel_timeline *first;
- /*
* We open-code a llist here to include the additional tag [BIT(0)]* so that we know when the timeline is already on a* retirement queue: either this engine or another.** However, we rely on that a timeline can only be active on a single* engine at any one time and that add_retire() is called before the* engine releases the timeline and transferred to another to retire.*/- if (READ_ONCE(tl->retire)) /* already queued */
return false;- intel_timeline_get(tl);
- first = READ_ONCE(engine->retire);
- do
tl->retire = ptr_pack_bits(first, 1, 1);- while (!try_cmpxchg(&engine->retire, &first, tl));
- return !first;
+}
+void intel_engine_add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl)+{
- if (add_retire(engine, tl))
schedule_work(&engine->retire_work);+}
+void intel_engine_init_retire(struct intel_engine_cs *engine) +{
- INIT_WORK(&engine->retire_work, engine_retire);
+}
+void intel_engine_fini_retire(struct intel_engine_cs *engine) +{
- flush_work(&engine->retire_work);
- GEM_BUG_ON(engine->retire);
+}
static noinline struct i915_request * request_alloc_slow(struct intel_timeline *tl, gfp_t gfp) { diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 3a3e7bbf19ff..40caa2f3f4a4 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -445,5 +445,9 @@ static inline bool i915_request_has_nopreempt(const struct i915_request *rq) } bool i915_retire_requests(struct drm_i915_private *i915); +void intel_engine_init_retire(struct intel_engine_cs *engine); +void intel_engine_add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl);+void intel_engine_fini_retire(struct intel_engine_cs *engine);
#endif /* I915_REQUEST_H */
2.26.0
Hi Greg,
Could you queue this one up as well?
What is the git commit id of this in Linus's tree?
Hi,
[note not involved in the respective patch, but noticed your question and saw the context]
On Sun, Apr 12, 2020 at 09:56:07AM +0200, Greg KH wrote:
On Sun, Apr 12, 2020 at 12:48:51AM -0700, Sultan Alsawaf wrote:
On Tue, Apr 07, 2020 at 01:43:45PM -0700, Sultan Alsawaf wrote:
From: Chris Wilson chris@chris-wilson.co.uk
The major drawback of commit 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") is that it disables RC6 while Skylake (and friends) is active, and we do not consider the GPU idle until all outstanding requests have been retired and the engine switched over to the kernel context. If userspace is idle, this task falls onto our background idle worker, which only runs roughly once a second, meaning that userspace has to have been idle for a couple of seconds before we enable RC6 again. Naturally, this causes us to consume considerably more energy than before as powersaving is effectively disabled while a display server (here's looking at you Xorg) is running.
As execlists will get a completion event as each context is completed, we can use this interrupt to queue a retire worker bound to this engine to cleanup idle timelines. We will then immediately notice the idle engine (without userspace intervention or the aid of the background retire worker) and start parking the GPU. Thus during light workloads, we will do much more work to idle the GPU faster... Hopefully with commensurate power saving!
v2: Watch context completions and only look at those local to the engine when retiring to reduce the amount of excess work we perform.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 References: 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") References: 2248a28384fe ("drm/i915/gen8+: Add RC6 CTX corruption WA") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris... (cherry picked from commit 4f88f8747fa43c97c3b3712d8d87295ea757cc51)
For the backport to 5.4, struct_mutex needs to be held while retiring so that retirement doesn't race with vma destruction. Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com
drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + drivers/gpu/drm/i915/i915_request.c | 75 +++++++++++++++++++ drivers/gpu/drm/i915/i915_request.h | 4 + 7 files changed, 101 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 4ce8626b140e..f732a2177cd0 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -600,6 +600,7 @@ static int intel_engine_setup_common(struct intel_engine_cs *engine) intel_engine_init_hangcheck(engine); intel_engine_init_cmd_parser(engine); intel_engine_init__pm(engine);
- intel_engine_init_retire(engine);
intel_engine_pool_init(&engine->pool); @@ -807,6 +808,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine) cleanup_status_page(engine);
- intel_engine_fini_retire(engine); intel_engine_pool_fini(&engine->pool); intel_engine_fini_breadcrumbs(engine); intel_engine_cleanup_cmd_parser(engine);
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index c77c9518c58b..1eb7189f88e1 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -471,6 +471,14 @@ struct intel_engine_cs { struct intel_engine_execlists execlists;
- /*
* Keep track of completed timelines on this engine for early* retirement with the goal of quickly enabling powersaving as* soon as the engine is idle.*/- struct intel_timeline *retire;
- struct work_struct retire_work;
- /* status_notifier: list of callbacks for context-switch changes */ struct atomic_notifier_head context_status_notifier;
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 66f6d1a897f2..a1538c8f7922 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -606,6 +606,14 @@ __execlists_schedule_out(struct i915_request *rq, { struct intel_context * const ce = rq->hw_context;
- /*
* If we have just completed this context, the engine may now be* idle and we want to re-enter powersaving.*/- if (list_is_last(&rq->link, &ce->timeline->requests) &&
i915_request_completed(rq))intel_engine_add_retire(engine, ce->timeline);- intel_engine_context_out(engine); execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT); intel_gt_pm_put(engine->gt);
diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c index 9cb01d9828f1..63515e3caaf2 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline.c +++ b/drivers/gpu/drm/i915/gt/intel_timeline.c @@ -282,6 +282,7 @@ void intel_timeline_fini(struct intel_timeline *timeline) { GEM_BUG_ON(atomic_read(&timeline->pin_count)); GEM_BUG_ON(!list_empty(&timeline->requests));
- GEM_BUG_ON(timeline->retire);
if (timeline->hwsp_cacheline) cacheline_free(timeline->hwsp_cacheline); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline_types.h b/drivers/gpu/drm/i915/gt/intel_timeline_types.h index 2b1baf2fcc8e..adf2d14ef647 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline_types.h +++ b/drivers/gpu/drm/i915/gt/intel_timeline_types.h @@ -65,6 +65,9 @@ struct intel_timeline { */ struct i915_active_request last_request;
- /** A chain of completed timelines ready for early retirement. */
- struct intel_timeline *retire;
- /**
- We track the most recent seqno that we wait on in every context so
- that we only have to emit a new await and dependency on a more
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 0d39038898d4..35457fda350c 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -600,6 +600,81 @@ static void retire_requests(struct intel_timeline *tl) break; } +static void engine_retire(struct work_struct *work) +{
- struct intel_engine_cs *engine =
container_of(work, typeof(*engine), retire_work);- struct intel_timeline *tl = xchg(&engine->retire, NULL);
- do {
struct intel_timeline *next = xchg(&tl->retire, NULL);/** Our goal here is to retire _idle_ timelines as soon as* possible (as they are idle, we do not expect userspace* to be cleaning up anytime soon).** If the timeline is currently locked, either it is being* retired elsewhere or about to be!*/mutex_lock(&engine->i915->drm.struct_mutex);if (mutex_trylock(&tl->mutex)) {retire_requests(tl);mutex_unlock(&tl->mutex);}mutex_unlock(&engine->i915->drm.struct_mutex);intel_timeline_put(tl);GEM_BUG_ON(!next);tl = ptr_mask_bits(next, 1);- } while (tl);
+}
+static bool add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl)+{
- struct intel_timeline *first;
- /*
* We open-code a llist here to include the additional tag [BIT(0)]* so that we know when the timeline is already on a* retirement queue: either this engine or another.** However, we rely on that a timeline can only be active on a single* engine at any one time and that add_retire() is called before the* engine releases the timeline and transferred to another to retire.*/- if (READ_ONCE(tl->retire)) /* already queued */
return false;- intel_timeline_get(tl);
- first = READ_ONCE(engine->retire);
- do
tl->retire = ptr_pack_bits(first, 1, 1);- while (!try_cmpxchg(&engine->retire, &first, tl));
- return !first;
+}
+void intel_engine_add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl)+{
- if (add_retire(engine, tl))
schedule_work(&engine->retire_work);+}
+void intel_engine_init_retire(struct intel_engine_cs *engine) +{
- INIT_WORK(&engine->retire_work, engine_retire);
+}
+void intel_engine_fini_retire(struct intel_engine_cs *engine) +{
- flush_work(&engine->retire_work);
- GEM_BUG_ON(engine->retire);
+}
static noinline struct i915_request * request_alloc_slow(struct intel_timeline *tl, gfp_t gfp) { diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 3a3e7bbf19ff..40caa2f3f4a4 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -445,5 +445,9 @@ static inline bool i915_request_has_nopreempt(const struct i915_request *rq) } bool i915_retire_requests(struct drm_i915_private *i915); +void intel_engine_init_retire(struct intel_engine_cs *engine); +void intel_engine_add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl);+void intel_engine_fini_retire(struct intel_engine_cs *engine);
#endif /* I915_REQUEST_H */
2.26.0
Hi Greg,
Could you queue this one up as well?
What is the git commit id of this in Linus's tree?
This appears to be 4f88f8747fa43c97c3b3712d8d87295ea757cc51 upstream, but there is as well this comment added:
For the backport to 5.4, struct_mutex needs to be held while retiring so that retirement doesn't race with vma destruction. Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com
Regards, Salvatore
On Sun, Apr 12, 2020 at 09:56:07AM +0200, Greg KH wrote:
On Sun, Apr 12, 2020 at 12:48:51AM -0700, Sultan Alsawaf wrote:
Hi Greg,
Could you queue this one up as well?
What is the git commit id of this in Linus's tree?
Sorry, I botched the commit message formatting. I'll send a patch with the correct message formatting now.
Sultan
From: Chris Wilson chris@chris-wilson.co.uk
commit 4f88f8747fa43c97c3b3712d8d87295ea757cc51 upstream.
The major drawback of commit 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") is that it disables RC6 while Skylake (and friends) is active, and we do not consider the GPU idle until all outstanding requests have been retired and the engine switched over to the kernel context. If userspace is idle, this task falls onto our background idle worker, which only runs roughly once a second, meaning that userspace has to have been idle for a couple of seconds before we enable RC6 again. Naturally, this causes us to consume considerably more energy than before as powersaving is effectively disabled while a display server (here's looking at you Xorg) is running.
As execlists will get a completion event as each context is completed, we can use this interrupt to queue a retire worker bound to this engine to cleanup idle timelines. We will then immediately notice the idle engine (without userspace intervention or the aid of the background retire worker) and start parking the GPU. Thus during light workloads, we will do much more work to idle the GPU faster... Hopefully with commensurate power saving!
v2: Watch context completions and only look at those local to the engine when retiring to reduce the amount of excess work we perform.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 References: 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") References: 2248a28384fe ("drm/i915/gen8+: Add RC6 CTX corruption WA") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris... [Sultan: for the backport to 5.4, struct_mutex needs to be held while retiring so that retirement doesn't race with vma destruction.] Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com --- drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + drivers/gpu/drm/i915/i915_request.c | 75 +++++++++++++++++++ drivers/gpu/drm/i915/i915_request.h | 4 + 7 files changed, 101 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 4ce8626b140e..f732a2177cd0 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -600,6 +600,7 @@ static int intel_engine_setup_common(struct intel_engine_cs *engine) intel_engine_init_hangcheck(engine); intel_engine_init_cmd_parser(engine); intel_engine_init__pm(engine); + intel_engine_init_retire(engine);
intel_engine_pool_init(&engine->pool);
@@ -807,6 +808,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine)
cleanup_status_page(engine);
+ intel_engine_fini_retire(engine); intel_engine_pool_fini(&engine->pool); intel_engine_fini_breadcrumbs(engine); intel_engine_cleanup_cmd_parser(engine); diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index c77c9518c58b..1eb7189f88e1 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -471,6 +471,14 @@ struct intel_engine_cs {
struct intel_engine_execlists execlists;
+ /* + * Keep track of completed timelines on this engine for early + * retirement with the goal of quickly enabling powersaving as + * soon as the engine is idle. + */ + struct intel_timeline *retire; + struct work_struct retire_work; + /* status_notifier: list of callbacks for context-switch changes */ struct atomic_notifier_head context_status_notifier;
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 66f6d1a897f2..a1538c8f7922 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -606,6 +606,14 @@ __execlists_schedule_out(struct i915_request *rq, { struct intel_context * const ce = rq->hw_context;
+ /* + * If we have just completed this context, the engine may now be + * idle and we want to re-enter powersaving. + */ + if (list_is_last(&rq->link, &ce->timeline->requests) && + i915_request_completed(rq)) + intel_engine_add_retire(engine, ce->timeline); + intel_engine_context_out(engine); execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT); intel_gt_pm_put(engine->gt); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c index 9cb01d9828f1..63515e3caaf2 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline.c +++ b/drivers/gpu/drm/i915/gt/intel_timeline.c @@ -282,6 +282,7 @@ void intel_timeline_fini(struct intel_timeline *timeline) { GEM_BUG_ON(atomic_read(&timeline->pin_count)); GEM_BUG_ON(!list_empty(&timeline->requests)); + GEM_BUG_ON(timeline->retire);
if (timeline->hwsp_cacheline) cacheline_free(timeline->hwsp_cacheline); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline_types.h b/drivers/gpu/drm/i915/gt/intel_timeline_types.h index 2b1baf2fcc8e..adf2d14ef647 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline_types.h +++ b/drivers/gpu/drm/i915/gt/intel_timeline_types.h @@ -65,6 +65,9 @@ struct intel_timeline { */ struct i915_active_request last_request;
+ /** A chain of completed timelines ready for early retirement. */ + struct intel_timeline *retire; + /** * We track the most recent seqno that we wait on in every context so * that we only have to emit a new await and dependency on a more diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 0d39038898d4..35457fda350c 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -600,6 +600,81 @@ static void retire_requests(struct intel_timeline *tl) break; }
+static void engine_retire(struct work_struct *work) +{ + struct intel_engine_cs *engine = + container_of(work, typeof(*engine), retire_work); + struct intel_timeline *tl = xchg(&engine->retire, NULL); + + do { + struct intel_timeline *next = xchg(&tl->retire, NULL); + + /* + * Our goal here is to retire _idle_ timelines as soon as + * possible (as they are idle, we do not expect userspace + * to be cleaning up anytime soon). + * + * If the timeline is currently locked, either it is being + * retired elsewhere or about to be! + */ + mutex_lock(&engine->i915->drm.struct_mutex); + if (mutex_trylock(&tl->mutex)) { + retire_requests(tl); + mutex_unlock(&tl->mutex); + } + mutex_unlock(&engine->i915->drm.struct_mutex); + intel_timeline_put(tl); + + GEM_BUG_ON(!next); + tl = ptr_mask_bits(next, 1); + } while (tl); +} + +static bool add_retire(struct intel_engine_cs *engine, + struct intel_timeline *tl) +{ + struct intel_timeline *first; + + /* + * We open-code a llist here to include the additional tag [BIT(0)] + * so that we know when the timeline is already on a + * retirement queue: either this engine or another. + * + * However, we rely on that a timeline can only be active on a single + * engine at any one time and that add_retire() is called before the + * engine releases the timeline and transferred to another to retire. + */ + + if (READ_ONCE(tl->retire)) /* already queued */ + return false; + + intel_timeline_get(tl); + first = READ_ONCE(engine->retire); + do + tl->retire = ptr_pack_bits(first, 1, 1); + while (!try_cmpxchg(&engine->retire, &first, tl)); + + return !first; +} + +void intel_engine_add_retire(struct intel_engine_cs *engine, + struct intel_timeline *tl) +{ + if (add_retire(engine, tl)) + schedule_work(&engine->retire_work); +} + +void intel_engine_init_retire(struct intel_engine_cs *engine) +{ + INIT_WORK(&engine->retire_work, engine_retire); +} + +void intel_engine_fini_retire(struct intel_engine_cs *engine) +{ + flush_work(&engine->retire_work); + GEM_BUG_ON(engine->retire); +} + static noinline struct i915_request * request_alloc_slow(struct intel_timeline *tl, gfp_t gfp) { diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 3a3e7bbf19ff..40caa2f3f4a4 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -445,5 +445,9 @@ static inline bool i915_request_has_nopreempt(const struct i915_request *rq) }
bool i915_retire_requests(struct drm_i915_private *i915); +void intel_engine_init_retire(struct intel_engine_cs *engine); +void intel_engine_add_retire(struct intel_engine_cs *engine, + struct intel_timeline *tl); +void intel_engine_fini_retire(struct intel_engine_cs *engine);
#endif /* I915_REQUEST_H */
On Mon, Apr 13, 2020 at 08:29:30AM -0700, Sultan Alsawaf wrote:
From: Chris Wilson chris@chris-wilson.co.uk
commit 4f88f8747fa43c97c3b3712d8d87295ea757cc51 upstream.
The major drawback of commit 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") is that it disables RC6 while Skylake (and friends) is active, and we do not consider the GPU idle until all outstanding requests have been retired and the engine switched over to the kernel context. If userspace is idle, this task falls onto our background idle worker, which only runs roughly once a second, meaning that userspace has to have been idle for a couple of seconds before we enable RC6 again. Naturally, this causes us to consume considerably more energy than before as powersaving is effectively disabled while a display server (here's looking at you Xorg) is running.
As execlists will get a completion event as each context is completed, we can use this interrupt to queue a retire worker bound to this engine to cleanup idle timelines. We will then immediately notice the idle engine (without userspace intervention or the aid of the background retire worker) and start parking the GPU. Thus during light workloads, we will do much more work to idle the GPU faster... Hopefully with commensurate power saving!
v2: Watch context completions and only look at those local to the engine when retiring to reduce the amount of excess work we perform.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 References: 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") References: 2248a28384fe ("drm/i915/gen8+: Add RC6 CTX corruption WA") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris... [Sultan: for the backport to 5.4, struct_mutex needs to be held while retiring so that retirement doesn't race with vma destruction.] Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com
drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + drivers/gpu/drm/i915/i915_request.c | 75 +++++++++++++++++++ drivers/gpu/drm/i915/i915_request.h | 4 + 7 files changed, 101 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 4ce8626b140e..f732a2177cd0 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -600,6 +600,7 @@ static int intel_engine_setup_common(struct intel_engine_cs *engine) intel_engine_init_hangcheck(engine); intel_engine_init_cmd_parser(engine); intel_engine_init__pm(engine);
- intel_engine_init_retire(engine);
intel_engine_pool_init(&engine->pool); @@ -807,6 +808,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine) cleanup_status_page(engine);
- intel_engine_fini_retire(engine); intel_engine_pool_fini(&engine->pool); intel_engine_fini_breadcrumbs(engine); intel_engine_cleanup_cmd_parser(engine);
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index c77c9518c58b..1eb7189f88e1 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -471,6 +471,14 @@ struct intel_engine_cs { struct intel_engine_execlists execlists;
- /*
* Keep track of completed timelines on this engine for early* retirement with the goal of quickly enabling powersaving as* soon as the engine is idle.*/- struct intel_timeline *retire;
- struct work_struct retire_work;
- /* status_notifier: list of callbacks for context-switch changes */ struct atomic_notifier_head context_status_notifier;
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 66f6d1a897f2..a1538c8f7922 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -606,6 +606,14 @@ __execlists_schedule_out(struct i915_request *rq, { struct intel_context * const ce = rq->hw_context;
- /*
* If we have just completed this context, the engine may now be* idle and we want to re-enter powersaving.*/- if (list_is_last(&rq->link, &ce->timeline->requests) &&
i915_request_completed(rq))intel_engine_add_retire(engine, ce->timeline);- intel_engine_context_out(engine); execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT); intel_gt_pm_put(engine->gt);
diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c index 9cb01d9828f1..63515e3caaf2 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline.c +++ b/drivers/gpu/drm/i915/gt/intel_timeline.c @@ -282,6 +282,7 @@ void intel_timeline_fini(struct intel_timeline *timeline) { GEM_BUG_ON(atomic_read(&timeline->pin_count)); GEM_BUG_ON(!list_empty(&timeline->requests));
- GEM_BUG_ON(timeline->retire);
if (timeline->hwsp_cacheline) cacheline_free(timeline->hwsp_cacheline); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline_types.h b/drivers/gpu/drm/i915/gt/intel_timeline_types.h index 2b1baf2fcc8e..adf2d14ef647 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline_types.h +++ b/drivers/gpu/drm/i915/gt/intel_timeline_types.h @@ -65,6 +65,9 @@ struct intel_timeline { */ struct i915_active_request last_request;
- /** A chain of completed timelines ready for early retirement. */
- struct intel_timeline *retire;
- /**
- We track the most recent seqno that we wait on in every context so
- that we only have to emit a new await and dependency on a more
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 0d39038898d4..35457fda350c 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -600,6 +600,81 @@ static void retire_requests(struct intel_timeline *tl) break; } +static void engine_retire(struct work_struct *work) +{
- struct intel_engine_cs *engine =
container_of(work, typeof(*engine), retire_work);- struct intel_timeline *tl = xchg(&engine->retire, NULL);
- do {
struct intel_timeline *next = xchg(&tl->retire, NULL);/** Our goal here is to retire _idle_ timelines as soon as* possible (as they are idle, we do not expect userspace* to be cleaning up anytime soon).** If the timeline is currently locked, either it is being* retired elsewhere or about to be!*/mutex_lock(&engine->i915->drm.struct_mutex);if (mutex_trylock(&tl->mutex)) {retire_requests(tl);mutex_unlock(&tl->mutex);}mutex_unlock(&engine->i915->drm.struct_mutex);intel_timeline_put(tl);GEM_BUG_ON(!next);tl = ptr_mask_bits(next, 1);- } while (tl);
+}
+static bool add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl)+{
- struct intel_timeline *first;
- /*
* We open-code a llist here to include the additional tag [BIT(0)]* so that we know when the timeline is already on a* retirement queue: either this engine or another.** However, we rely on that a timeline can only be active on a single* engine at any one time and that add_retire() is called before the* engine releases the timeline and transferred to another to retire.*/- if (READ_ONCE(tl->retire)) /* already queued */
return false;- intel_timeline_get(tl);
- first = READ_ONCE(engine->retire);
- do
tl->retire = ptr_pack_bits(first, 1, 1);- while (!try_cmpxchg(&engine->retire, &first, tl));
- return !first;
+}
+void intel_engine_add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl)+{
- if (add_retire(engine, tl))
schedule_work(&engine->retire_work);+}
+void intel_engine_init_retire(struct intel_engine_cs *engine) +{
- INIT_WORK(&engine->retire_work, engine_retire);
+}
+void intel_engine_fini_retire(struct intel_engine_cs *engine) +{
- flush_work(&engine->retire_work);
- GEM_BUG_ON(engine->retire);
+}
static noinline struct i915_request * request_alloc_slow(struct intel_timeline *tl, gfp_t gfp) { diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 3a3e7bbf19ff..40caa2f3f4a4 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -445,5 +445,9 @@ static inline bool i915_request_has_nopreempt(const struct i915_request *rq) } bool i915_retire_requests(struct drm_i915_private *i915); +void intel_engine_init_retire(struct intel_engine_cs *engine); +void intel_engine_add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl);+void intel_engine_fini_retire(struct intel_engine_cs *engine);
#endif /* I915_REQUEST_H */
2.26.0
Greg,
Could you take another look at this please and let me know if looks good to queue up?
Thanks, Sultan
On Fri, Apr 17, 2020 at 02:38:47AM -0700, Sultan Alsawaf wrote:
On Mon, Apr 13, 2020 at 08:29:30AM -0700, Sultan Alsawaf wrote:
From: Chris Wilson chris@chris-wilson.co.uk
commit 4f88f8747fa43c97c3b3712d8d87295ea757cc51 upstream.
The major drawback of commit 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") is that it disables RC6 while Skylake (and friends) is active, and we do not consider the GPU idle until all outstanding requests have been retired and the engine switched over to the kernel context. If userspace is idle, this task falls onto our background idle worker, which only runs roughly once a second, meaning that userspace has to have been idle for a couple of seconds before we enable RC6 again. Naturally, this causes us to consume considerably more energy than before as powersaving is effectively disabled while a display server (here's looking at you Xorg) is running.
As execlists will get a completion event as each context is completed, we can use this interrupt to queue a retire worker bound to this engine to cleanup idle timelines. We will then immediately notice the idle engine (without userspace intervention or the aid of the background retire worker) and start parking the GPU. Thus during light workloads, we will do much more work to idle the GPU faster... Hopefully with commensurate power saving!
v2: Watch context completions and only look at those local to the engine when retiring to reduce the amount of excess work we perform.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 References: 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") References: 2248a28384fe ("drm/i915/gen8+: Add RC6 CTX corruption WA") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris... [Sultan: for the backport to 5.4, struct_mutex needs to be held while retiring so that retirement doesn't race with vma destruction.] Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com
drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + drivers/gpu/drm/i915/i915_request.c | 75 +++++++++++++++++++ drivers/gpu/drm/i915/i915_request.h | 4 + 7 files changed, 101 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 4ce8626b140e..f732a2177cd0 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -600,6 +600,7 @@ static int intel_engine_setup_common(struct intel_engine_cs *engine) intel_engine_init_hangcheck(engine); intel_engine_init_cmd_parser(engine); intel_engine_init__pm(engine);
- intel_engine_init_retire(engine);
intel_engine_pool_init(&engine->pool); @@ -807,6 +808,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine) cleanup_status_page(engine);
- intel_engine_fini_retire(engine); intel_engine_pool_fini(&engine->pool); intel_engine_fini_breadcrumbs(engine); intel_engine_cleanup_cmd_parser(engine);
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index c77c9518c58b..1eb7189f88e1 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -471,6 +471,14 @@ struct intel_engine_cs { struct intel_engine_execlists execlists;
- /*
* Keep track of completed timelines on this engine for early* retirement with the goal of quickly enabling powersaving as* soon as the engine is idle.*/- struct intel_timeline *retire;
- struct work_struct retire_work;
- /* status_notifier: list of callbacks for context-switch changes */ struct atomic_notifier_head context_status_notifier;
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 66f6d1a897f2..a1538c8f7922 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -606,6 +606,14 @@ __execlists_schedule_out(struct i915_request *rq, { struct intel_context * const ce = rq->hw_context;
- /*
* If we have just completed this context, the engine may now be* idle and we want to re-enter powersaving.*/- if (list_is_last(&rq->link, &ce->timeline->requests) &&
i915_request_completed(rq))intel_engine_add_retire(engine, ce->timeline);- intel_engine_context_out(engine); execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT); intel_gt_pm_put(engine->gt);
diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c index 9cb01d9828f1..63515e3caaf2 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline.c +++ b/drivers/gpu/drm/i915/gt/intel_timeline.c @@ -282,6 +282,7 @@ void intel_timeline_fini(struct intel_timeline *timeline) { GEM_BUG_ON(atomic_read(&timeline->pin_count)); GEM_BUG_ON(!list_empty(&timeline->requests));
- GEM_BUG_ON(timeline->retire);
if (timeline->hwsp_cacheline) cacheline_free(timeline->hwsp_cacheline); diff --git a/drivers/gpu/drm/i915/gt/intel_timeline_types.h b/drivers/gpu/drm/i915/gt/intel_timeline_types.h index 2b1baf2fcc8e..adf2d14ef647 100644 --- a/drivers/gpu/drm/i915/gt/intel_timeline_types.h +++ b/drivers/gpu/drm/i915/gt/intel_timeline_types.h @@ -65,6 +65,9 @@ struct intel_timeline { */ struct i915_active_request last_request;
- /** A chain of completed timelines ready for early retirement. */
- struct intel_timeline *retire;
- /**
- We track the most recent seqno that we wait on in every context so
- that we only have to emit a new await and dependency on a more
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 0d39038898d4..35457fda350c 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -600,6 +600,81 @@ static void retire_requests(struct intel_timeline *tl) break; } +static void engine_retire(struct work_struct *work) +{
- struct intel_engine_cs *engine =
container_of(work, typeof(*engine), retire_work);- struct intel_timeline *tl = xchg(&engine->retire, NULL);
- do {
struct intel_timeline *next = xchg(&tl->retire, NULL);/** Our goal here is to retire _idle_ timelines as soon as* possible (as they are idle, we do not expect userspace* to be cleaning up anytime soon).** If the timeline is currently locked, either it is being* retired elsewhere or about to be!*/mutex_lock(&engine->i915->drm.struct_mutex);if (mutex_trylock(&tl->mutex)) {retire_requests(tl);mutex_unlock(&tl->mutex);}mutex_unlock(&engine->i915->drm.struct_mutex);intel_timeline_put(tl);GEM_BUG_ON(!next);tl = ptr_mask_bits(next, 1);- } while (tl);
+}
+static bool add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl)+{
- struct intel_timeline *first;
- /*
* We open-code a llist here to include the additional tag [BIT(0)]* so that we know when the timeline is already on a* retirement queue: either this engine or another.** However, we rely on that a timeline can only be active on a single* engine at any one time and that add_retire() is called before the* engine releases the timeline and transferred to another to retire.*/- if (READ_ONCE(tl->retire)) /* already queued */
return false;- intel_timeline_get(tl);
- first = READ_ONCE(engine->retire);
- do
tl->retire = ptr_pack_bits(first, 1, 1);- while (!try_cmpxchg(&engine->retire, &first, tl));
- return !first;
+}
+void intel_engine_add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl)+{
- if (add_retire(engine, tl))
schedule_work(&engine->retire_work);+}
+void intel_engine_init_retire(struct intel_engine_cs *engine) +{
- INIT_WORK(&engine->retire_work, engine_retire);
+}
+void intel_engine_fini_retire(struct intel_engine_cs *engine) +{
- flush_work(&engine->retire_work);
- GEM_BUG_ON(engine->retire);
+}
static noinline struct i915_request * request_alloc_slow(struct intel_timeline *tl, gfp_t gfp) { diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index 3a3e7bbf19ff..40caa2f3f4a4 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -445,5 +445,9 @@ static inline bool i915_request_has_nopreempt(const struct i915_request *rq) } bool i915_retire_requests(struct drm_i915_private *i915); +void intel_engine_init_retire(struct intel_engine_cs *engine); +void intel_engine_add_retire(struct intel_engine_cs *engine,
struct intel_timeline *tl);+void intel_engine_fini_retire(struct intel_engine_cs *engine);
#endif /* I915_REQUEST_H */
2.26.0
Greg,
Could you take another look at this please and let me know if looks good to queue up?
I have no idea, I want an ack from the maintainers of this driver to say it is ok, given these threads with no solid agreement.
thanks,
greg k-h
On Mon, Apr 13, 2020 at 08:29:30AM -0700, Sultan Alsawaf wrote:
From: Chris Wilson chris@chris-wilson.co.uk
commit 4f88f8747fa43c97c3b3712d8d87295ea757cc51 upstream.
The major drawback of commit 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") is that it disables RC6 while Skylake (and friends) is active, and we do not consider the GPU idle until all outstanding requests have been retired and the engine switched over to the kernel context. If userspace is idle, this task falls onto our background idle worker, which only runs roughly once a second, meaning that userspace has to have been idle for a couple of seconds before we enable RC6 again. Naturally, this causes us to consume considerably more energy than before as powersaving is effectively disabled while a display server (here's looking at you Xorg) is running.
As execlists will get a completion event as each context is completed, we can use this interrupt to queue a retire worker bound to this engine to cleanup idle timelines. We will then immediately notice the idle engine (without userspace intervention or the aid of the background retire worker) and start parking the GPU. Thus during light workloads, we will do much more work to idle the GPU faster... Hopefully with commensurate power saving!
v2: Watch context completions and only look at those local to the engine when retiring to reduce the amount of excess work we perform.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315 References: 7e34f4e4aad3 ("drm/i915/gen8+: Add RC6 CTX corruption WA") References: 2248a28384fe ("drm/i915/gen8+: Add RC6 CTX corruption WA") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20191125105858.1718307-3-chris... [Sultan: for the backport to 5.4, struct_mutex needs to be held while retiring so that retirement doesn't race with vma destruction.] Signed-off-by: Sultan Alsawaf sultan@kerneltoast.com
drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 + drivers/gpu/drm/i915/gt/intel_engine_types.h | 8 ++ drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++ drivers/gpu/drm/i915/gt/intel_timeline.c | 1 + .../gpu/drm/i915/gt/intel_timeline_types.h | 3 + drivers/gpu/drm/i915/i915_request.c | 75 +++++++++++++++++++ drivers/gpu/drm/i915/i915_request.h | 4 + 7 files changed, 101 insertions(+)
Why are you not cc:ing all of the relevant people on these patches? That's not ok, I'm just going to drop all of these requests until that happens, and I get an ack from the developers/maintainers involved.
thanks,
greg k-h
linux-stable-mirror@lists.linaro.org
-
Chris Wilson -
Greg KH -
Salvatore Bonaccorso -
Sultan Alsawaf