FAILED: patch "[PATCH] cpuidle: governors: menu: Select polling state in some more" failed to apply to 6.17-stable tree
The patch below does not apply to the 6.17-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.17.y git checkout FETCH_HEAD git cherry-pick -x db86f55bf81a3a297be05ee8775ae9a8c6e3a599 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025110243-dupe-pentagram-9b47@gregkh' --subject-prefix 'PATCH 6.17.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From db86f55bf81a3a297be05ee8775ae9a8c6e3a599 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" rafael.j.wysocki@intel.com Date: Thu, 23 Oct 2025 19:12:57 +0200 Subject: [PATCH] cpuidle: governors: menu: Select polling state in some more cases
A throughput regression of 11% introduced by commit 779b1a1cb13a ("cpuidle: governors: menu: Avoid selecting states with too much latency") has been reported and it is related to the case when the menu governor checks if selecting a proper idle state instead of a polling one makes sense.
In particular, it is questionable to do so if the exit latency of the idle state in question exceeds the predicted idle duration, so add a check for that, which is sufficient to make the reported regression go away, and update the related code comment accordingly.
Fixes: 779b1a1cb13a ("cpuidle: governors: menu: Avoid selecting states with too much latency") Closes: https://lore.kernel.org/linux-pm/004501dc43c9%24ec8aa930%24c59ffb90%24@telus... Reported-by: Doug Smythies dsmythies@telus.net Tested-by: Doug Smythies dsmythies@telus.net Cc: All applicable stable@vger.kernel.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Christian Loehle christian.loehle@arm.com Link: https://patch.msgid.link/12786727.O9o76ZdvQC@rafael.j.wysocki
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 7d21fb5a72f4..23239b0c04f9 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -318,10 +318,13 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
/* * Use a physical idle state, not busy polling, unless a timer - * is going to trigger soon enough. + * is going to trigger soon enough or the exit latency of the + * idle state in question is greater than the predicted idle + * duration. */ if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && - s->target_residency_ns <= data->next_timer_ns) { + s->target_residency_ns <= data->next_timer_ns && + s->exit_latency_ns <= predicted_ns) { predicted_ns = s->target_residency_ns; idx = i; break;
From: "Rafael J. Wysocki" rafael.j.wysocki@intel.com
[ Upstream commit 17224c1d2574d29668c4879e1fbf36d6f68cd22b ]
Reduce the indentation level in the main loop of menu_select() by rearranging some checks and assignments in it.
No intentional functional impact.
Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Christian Loehle christian.loehle@arm.com Link: https://patch.msgid.link/2389215.ElGaqSPkdT@rafael.j.wysocki Stable-dep-of: db86f55bf81a ("cpuidle: governors: menu: Select polling state in some more cases") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/cpuidle/governors/menu.c | 70 ++++++++++++++++---------------- 1 file changed, 36 insertions(+), 34 deletions(-)
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index d54a60a024e46..7d21fb5a72f40 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -311,45 +311,47 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, if (s->exit_latency_ns > latency_req) break;
- if (s->target_residency_ns > predicted_ns) { - /* - * Use a physical idle state, not busy polling, unless - * a timer is going to trigger soon enough. - */ - if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && - s->target_residency_ns <= data->next_timer_ns) { - predicted_ns = s->target_residency_ns; - idx = i; - break; - } - if (predicted_ns < TICK_NSEC) - break; - - if (!tick_nohz_tick_stopped()) { - /* - * If the state selected so far is shallow, - * waking up early won't hurt, so retain the - * tick in that case and let the governor run - * again in the next iteration of the loop. - */ - predicted_ns = drv->states[idx].target_residency_ns; - break; - } + if (s->target_residency_ns <= predicted_ns) { + idx = i; + continue; + } + + /* + * Use a physical idle state, not busy polling, unless a timer + * is going to trigger soon enough. + */ + if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && + s->target_residency_ns <= data->next_timer_ns) { + predicted_ns = s->target_residency_ns; + idx = i; + break; + }
+ if (predicted_ns < TICK_NSEC) + break; + + if (!tick_nohz_tick_stopped()) { /* - * If the state selected so far is shallow and this - * state's target residency matches the time till the - * closest timer event, select this one to avoid getting - * stuck in the shallow one for too long. + * If the state selected so far is shallow, waking up + * early won't hurt, so retain the tick in that case and + * let the governor run again in the next iteration of + * the idle loop. */ - if (drv->states[idx].target_residency_ns < TICK_NSEC && - s->target_residency_ns <= delta_tick) - idx = i; - - return idx; + predicted_ns = drv->states[idx].target_residency_ns; + break; }
- idx = i; + /* + * If the state selected so far is shallow and this state's + * target residency matches the time till the closest timer + * event, select this one to avoid getting stuck in the shallow + * one for too long. + */ + if (drv->states[idx].target_residency_ns < TICK_NSEC && + s->target_residency_ns <= delta_tick) + idx = i; + + return idx; }
if (idx == -1)
From: "Rafael J. Wysocki" rafael.j.wysocki@intel.com
[ Upstream commit db86f55bf81a3a297be05ee8775ae9a8c6e3a599 ]
A throughput regression of 11% introduced by commit 779b1a1cb13a ("cpuidle: governors: menu: Avoid selecting states with too much latency") has been reported and it is related to the case when the menu governor checks if selecting a proper idle state instead of a polling one makes sense.
In particular, it is questionable to do so if the exit latency of the idle state in question exceeds the predicted idle duration, so add a check for that, which is sufficient to make the reported regression go away, and update the related code comment accordingly.
Fixes: 779b1a1cb13a ("cpuidle: governors: menu: Avoid selecting states with too much latency") Closes: https://lore.kernel.org/linux-pm/004501dc43c9%24ec8aa930%24c59ffb90%24@telus... Reported-by: Doug Smythies dsmythies@telus.net Tested-by: Doug Smythies dsmythies@telus.net Cc: All applicable stable@vger.kernel.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Christian Loehle christian.loehle@arm.com Link: https://patch.msgid.link/12786727.O9o76ZdvQC@rafael.j.wysocki Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/cpuidle/governors/menu.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 7d21fb5a72f40..23239b0c04f95 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -318,10 +318,13 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
/* * Use a physical idle state, not busy polling, unless a timer - * is going to trigger soon enough. + * is going to trigger soon enough or the exit latency of the + * idle state in question is greater than the predicted idle + * duration. */ if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && - s->target_residency_ns <= data->next_timer_ns) { + s->target_residency_ns <= data->next_timer_ns && + s->exit_latency_ns <= predicted_ns) { predicted_ns = s->target_residency_ns; idx = i; break;
linux-stable-mirror@lists.linaro.org
-
gregkh＠linuxfoundation.org -
Sasha Levin