6.12-stable review patch. If anyone has any objections, please let me know.
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From: Umesh Nerlige Ramappa umesh.nerlige.ramappa@intel.com
[ Upstream commit 59a0b46788d58fdcee8d2f6b4e619d264a1799bf ]
Active busyness of an engine is calculated using gt timestamp and the context switch in time. While capturing the gt timestamp, it's possible that the context switches out. This race could result in an active busyness value that is greater than the actual context runtime value by a small amount. This leads to a negative delta and throws off busyness calculations for the user.
If a subsequent count is smaller than the previous one, just return the previous one, since we expect the busyness to catch up.
Fixes: 77cdd054dd2c ("drm/i915/pmu: Connect engine busyness stats from GuC to pmu") Signed-off-by: Umesh Nerlige Ramappa umesh.nerlige.ramappa@intel.com Reviewed-by: John Harrison John.C.Harrison@Intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20241127174006.190128-3-umesh.... (cherry picked from commit cf907f6d294217985e9dafd9985dce874e04ca37) Signed-off-by: Tvrtko Ursulin tursulin@ursulin.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/i915/gt/intel_engine_types.h | 5 +++++ drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 5 ++++- 2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index ba55c059063d..fe1f85e5dda3 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -343,6 +343,11 @@ struct intel_engine_guc_stats { * @start_gt_clk: GT clock time of last idle to active transition. */ u64 start_gt_clk; + + /** + * @total: The last value of total returned + */ + u64 total; };
union intel_engine_tlb_inv_reg { diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index 4793759f4d4a..fbff9b9a067c 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -1378,9 +1378,12 @@ static ktime_t guc_engine_busyness(struct intel_engine_cs *engine, ktime_t *now) total += intel_gt_clock_interval_to_ns(gt, clk); }
+ if (total > stats->total) + stats->total = total; + spin_unlock_irqrestore(&guc->timestamp.lock, flags);
- return ns_to_ktime(total); + return ns_to_ktime(stats->total); }
static void guc_enable_busyness_worker(struct intel_guc *guc)