* [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq is idle @ 2021-06-18 7:23 Xuewen Yan 2021-06-29 3:11 ` Xuewen Yan 2021-06-29 13:50 ` Valentin Schneider 0 siblings, 2 replies; 7+ messages in thread From: Xuewen Yan @ 2021-06-18 7:23 UTC (permalink / raw) To: mingo, peterz, juri.lelli, vincent.guittot, dietmar.eggemann Cc: rostedt, bsegall, mgorman, bristot, linux-kernel, patrick.bellasi, zhang.lyra From: Xuewen Yan <xuewen.yan@unisoc.com> Now in uclamp_rq_util_with(), when the task != NULL, the uclamp_max as following: uc_rq_max = rq->uclamp[UCLAMP_MAX].value; uc_eff_max = uclamp_eff_value(p, UCLAMP_MAX); uclamp_max = max{uc_rq_max, uc_eff_max}; Consider the following scenario: (1)the rq is idle, the uc_rq_max is last task's UCLAMP_MAX; (2)the p's uc_eff_max < uc_rq_max. The result is the uclamp_max = uc_rq_max instead of uc_eff_max, it is unreasonable. The scenario often happens in find_energy_efficient_cpu(), when the task has smaller UCLAMP_MAX. Inserts whether the rq is idle in the uclamp_rq_util_with(). Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> --- kernel/sched/sched.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index a189bec13729..0feef6af89f2 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2550,7 +2550,10 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, if (p) { min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN)); - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); + if (rq->uclamp_flags & UCLAMP_FLAG_IDLE) + max_util = uclamp_eff_value(p, UCLAMP_MAX); + else + max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); } /* -- 2.25.1 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq is idle 2021-06-18 7:23 [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq is idle Xuewen Yan @ 2021-06-29 3:11 ` Xuewen Yan 2021-06-29 13:50 ` Valentin Schneider 1 sibling, 0 replies; 7+ messages in thread From: Xuewen Yan @ 2021-06-29 3:11 UTC (permalink / raw) To: Dietmar Eggemann, Qais Yousef, Quentin Perret Cc: Vincent Guittot, Steven Rostedt, Benjamin Segall, Mel Gorman, Juri Lelli, Daniel Bristot de Oliveira, linux-kernel, Patrick Bellasi, Chunyan Zhang, Ingo Molnar, Peter Zijlstra +cc Qais, Quentin Hi Dietmar, The patch has been around for a long time, and I think it makes sense for EAS. Do you have any suggestions or comments? Thanks! xuewen On Fri, Jun 18, 2021 at 3:24 PM Xuewen Yan <xuewen.yan94@gmail.com> wrote: > > From: Xuewen Yan <xuewen.yan@unisoc.com> > > Now in uclamp_rq_util_with(), when the task != NULL, the uclamp_max as following: > uc_rq_max = rq->uclamp[UCLAMP_MAX].value; > uc_eff_max = uclamp_eff_value(p, UCLAMP_MAX); > uclamp_max = max{uc_rq_max, uc_eff_max}; > > Consider the following scenario: > (1)the rq is idle, the uc_rq_max is last task's UCLAMP_MAX; > (2)the p's uc_eff_max < uc_rq_max. > > The result is the uclamp_max = uc_rq_max instead of uc_eff_max, it is unreasonable. > > The scenario often happens in find_energy_efficient_cpu(), when the task has smaller UCLAMP_MAX. > > Inserts whether the rq is idle in the uclamp_rq_util_with(). > > Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> > --- > kernel/sched/sched.h | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index a189bec13729..0feef6af89f2 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -2550,7 +2550,10 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, > > if (p) { > min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN)); > - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); > + if (rq->uclamp_flags & UCLAMP_FLAG_IDLE) > + max_util = uclamp_eff_value(p, UCLAMP_MAX); > + else > + max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); > } > > /* > -- > 2.25.1 > ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq is idle 2021-06-18 7:23 [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq is idle Xuewen Yan 2021-06-29 3:11 ` Xuewen Yan @ 2021-06-29 13:50 ` Valentin Schneider 2021-06-30 1:24 ` Xuewen Yan 1 sibling, 1 reply; 7+ messages in thread From: Valentin Schneider @ 2021-06-29 13:50 UTC (permalink / raw) To: Xuewen Yan, mingo, peterz, juri.lelli, vincent.guittot, dietmar.eggemann Cc: rostedt, bsegall, mgorman, bristot, linux-kernel, Patrick Bellasi, zhang.lyra +Cc Patrick's current address On 18/06/21 15:23, Xuewen Yan wrote: > From: Xuewen Yan <xuewen.yan@unisoc.com> > > Now in uclamp_rq_util_with(), when the task != NULL, the uclamp_max as following: > uc_rq_max = rq->uclamp[UCLAMP_MAX].value; > uc_eff_max = uclamp_eff_value(p, UCLAMP_MAX); > uclamp_max = max{uc_rq_max, uc_eff_max}; > > Consider the following scenario: > (1)the rq is idle, the uc_rq_max is last task's UCLAMP_MAX; > (2)the p's uc_eff_max < uc_rq_max. > > The result is the uclamp_max = uc_rq_max instead of uc_eff_max, it is unreasonable. > > The scenario often happens in find_energy_efficient_cpu(), when the task has smaller UCLAMP_MAX. > > Inserts whether the rq is idle in the uclamp_rq_util_with(). > > Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> > --- > kernel/sched/sched.h | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index a189bec13729..0feef6af89f2 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -2550,7 +2550,10 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, > > if (p) { > min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN)); > - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); > + if (rq->uclamp_flags & UCLAMP_FLAG_IDLE) > + max_util = uclamp_eff_value(p, UCLAMP_MAX); > + else > + max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); That makes sense to me - enqueuing the task will lift UCLAMP_FLAG_IDLE and set the rq clamp as the task's via uclamp_idle_reset(). Does this want a Fixes: 9d20ad7dfc9a ("sched/uclamp: Add uclamp_util_with()") ? Also, when we have UCLAMP_FLAG_IDLE, we don't even need to read the rq max - and I'm pretty sure the same applies to the rq min. What about something like: --- diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 6510f0a46789..a2c6f6ae6392 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2833,23 +2833,27 @@ static __always_inline unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, struct task_struct *p) { - unsigned long min_util; - unsigned long max_util; + unsigned long min_util = 0; + unsigned long max_util = 0; if (!static_branch_likely(&sched_uclamp_used)) return util; - min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value); - max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value); - if (p) { - min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN)); + min_util = uclamp_eff_value(p, UCLAMP_MIN); + max_util = uclamp_eff_value(p, UCLAMP_MAX); + + /* + * Ignore last runnable task's max clamp, as this task will + * reset it. Similarly, no need to read the rq's min clamp. + */ if (rq->uclamp_flags & UCLAMP_FLAG_IDLE) - max_util = uclamp_eff_value(p, UCLAMP_MAX); - else - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); + goto out; } + min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value)); + max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value)); +out: /* * Since CPU's {min,max}_util clamps are MAX aggregated considering * RUNNABLE tasks with _different_ clamps, we can end up with an ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq is idle 2021-06-29 13:50 ` Valentin Schneider @ 2021-06-30 1:24 ` Xuewen Yan 2021-06-30 11:31 ` Valentin Schneider 2021-06-30 14:11 ` Qais Yousef 0 siblings, 2 replies; 7+ messages in thread From: Xuewen Yan @ 2021-06-30 1:24 UTC (permalink / raw) To: Valentin Schneider Cc: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Benjamin Segall, Mel Gorman, Daniel Bristot de Oliveira, linux-kernel, Patrick Bellasi, Chunyan Zhang, Quentin Perret, Qais Yousef On Tue, Jun 29, 2021 at 9:50 PM Valentin Schneider <valentin.schneider@arm.com> wrote: > > > +Cc Patrick's current address > > On 18/06/21 15:23, Xuewen Yan wrote: > > From: Xuewen Yan <xuewen.yan@unisoc.com> > > > > Now in uclamp_rq_util_with(), when the task != NULL, the uclamp_max as following: > > uc_rq_max = rq->uclamp[UCLAMP_MAX].value; > > uc_eff_max = uclamp_eff_value(p, UCLAMP_MAX); > > uclamp_max = max{uc_rq_max, uc_eff_max}; > > > > Consider the following scenario: > > (1)the rq is idle, the uc_rq_max is last task's UCLAMP_MAX; > > (2)the p's uc_eff_max < uc_rq_max. > > > > The result is the uclamp_max = uc_rq_max instead of uc_eff_max, it is unreasonable. > > > > The scenario often happens in find_energy_efficient_cpu(), when the task has smaller UCLAMP_MAX. > > > > Inserts whether the rq is idle in the uclamp_rq_util_with(). > > > > Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> > > --- > > kernel/sched/sched.h | 5 ++++- > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > > index a189bec13729..0feef6af89f2 100644 > > --- a/kernel/sched/sched.h > > +++ b/kernel/sched/sched.h > > @@ -2550,7 +2550,10 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, > > > > if (p) { > > min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN)); > > - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); > > + if (rq->uclamp_flags & UCLAMP_FLAG_IDLE) > > + max_util = uclamp_eff_value(p, UCLAMP_MAX); > > + else > > + max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); > > That makes sense to me - enqueuing the task will lift UCLAMP_FLAG_IDLE and > set the rq clamp as the task's via uclamp_idle_reset(). > > Does this want a > > Fixes: 9d20ad7dfc9a ("sched/uclamp: Add uclamp_util_with()") > > ? Yes,add it. > > Also, when we have UCLAMP_FLAG_IDLE, we don't even need to read the rq max > - and I'm pretty sure the same applies to the rq min. What about something like: Good idea, I'll try it in V2. > > --- > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 6510f0a46789..a2c6f6ae6392 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -2833,23 +2833,27 @@ static __always_inline > unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, > struct task_struct *p) > { > - unsigned long min_util; > - unsigned long max_util; > + unsigned long min_util = 0; > + unsigned long max_util = 0; > > if (!static_branch_likely(&sched_uclamp_used)) > return util; > > - min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value); > - max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value); > - > if (p) { > - min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN)); > + min_util = uclamp_eff_value(p, UCLAMP_MIN); > + max_util = uclamp_eff_value(p, UCLAMP_MAX); > + > + /* > + * Ignore last runnable task's max clamp, as this task will > + * reset it. Similarly, no need to read the rq's min clamp. > + */ > if (rq->uclamp_flags & UCLAMP_FLAG_IDLE) > - max_util = uclamp_eff_value(p, UCLAMP_MAX); > - else > - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); > + goto out; > } > > + min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value)); > + max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value)); Is it necessary to use max_t here? although it is not the main problem... > +out: > /* > * Since CPU's {min,max}_util clamps are MAX aggregated considering > * RUNNABLE tasks with _different_ clamps, we can end up with an Thanks! xuewen ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq is idle 2021-06-30 1:24 ` Xuewen Yan @ 2021-06-30 11:31 ` Valentin Schneider 2021-06-30 12:05 ` Xuewen Yan 2021-06-30 14:11 ` Qais Yousef 1 sibling, 1 reply; 7+ messages in thread From: Valentin Schneider @ 2021-06-30 11:31 UTC (permalink / raw) To: Xuewen Yan Cc: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Benjamin Segall, Mel Gorman, Daniel Bristot de Oliveira, linux-kernel, Patrick Bellasi, Chunyan Zhang, Quentin Perret, Qais Yousef On 30/06/21 09:24, Xuewen Yan wrote: > On Tue, Jun 29, 2021 at 9:50 PM Valentin Schneider > <valentin.schneider@arm.com> wrote: >> + min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value)); >> + max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value)); > > Is it necessary to use max_t here? although it is not the main problem... > I got comparison warnings when using a regular max() - the RQ clamp values are unsigned int, whereas the local variable is unsigned long. >> +out: >> /* >> * Since CPU's {min,max}_util clamps are MAX aggregated considering >> * RUNNABLE tasks with _different_ clamps, we can end up with an > > Thanks! > xuewen ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq is idle 2021-06-30 11:31 ` Valentin Schneider @ 2021-06-30 12:05 ` Xuewen Yan 0 siblings, 0 replies; 7+ messages in thread From: Xuewen Yan @ 2021-06-30 12:05 UTC (permalink / raw) To: Valentin Schneider Cc: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Benjamin Segall, Mel Gorman, Daniel Bristot de Oliveira, linux-kernel, Patrick Bellasi, Chunyan Zhang, Quentin Perret, Qais Yousef On Wed, Jun 30, 2021 at 7:31 PM Valentin Schneider <valentin.schneider@arm.com> wrote: > > On 30/06/21 09:24, Xuewen Yan wrote: > > On Tue, Jun 29, 2021 at 9:50 PM Valentin Schneider > > <valentin.schneider@arm.com> wrote: > >> + min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value)); > >> + max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value)); > > > > Is it necessary to use max_t here? although it is not the main problem... > > > > I got comparison warnings when using a regular max() - the RQ clamp values > are unsigned int, whereas the local variable is unsigned long. Yes,I miss the rq clamp value's type. Thanks! xuewen ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq is idle 2021-06-30 1:24 ` Xuewen Yan 2021-06-30 11:31 ` Valentin Schneider @ 2021-06-30 14:11 ` Qais Yousef 1 sibling, 0 replies; 7+ messages in thread From: Qais Yousef @ 2021-06-30 14:11 UTC (permalink / raw) To: Xuewen Yan Cc: Valentin Schneider, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Benjamin Segall, Mel Gorman, Daniel Bristot de Oliveira, linux-kernel, Patrick Bellasi, Chunyan Zhang, Quentin Perret Thanks for the CC. On 06/30/21 09:24, Xuewen Yan wrote: > On Tue, Jun 29, 2021 at 9:50 PM Valentin Schneider > <valentin.schneider@arm.com> wrote: > > > > > > +Cc Patrick's current address > > > > On 18/06/21 15:23, Xuewen Yan wrote: > > > From: Xuewen Yan <xuewen.yan@unisoc.com> > > > > > > Now in uclamp_rq_util_with(), when the task != NULL, the uclamp_max as following: > > > uc_rq_max = rq->uclamp[UCLAMP_MAX].value; > > > uc_eff_max = uclamp_eff_value(p, UCLAMP_MAX); > > > uclamp_max = max{uc_rq_max, uc_eff_max}; > > > > > > Consider the following scenario: > > > (1)the rq is idle, the uc_rq_max is last task's UCLAMP_MAX; > > > (2)the p's uc_eff_max < uc_rq_max. > > > > > > The result is the uclamp_max = uc_rq_max instead of uc_eff_max, it is unreasonable. > > > > > > The scenario often happens in find_energy_efficient_cpu(), when the task has smaller UCLAMP_MAX. > > > > > > Inserts whether the rq is idle in the uclamp_rq_util_with(). > > > > > > Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> > > > --- > > > kernel/sched/sched.h | 5 ++++- > > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > > > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > > > index a189bec13729..0feef6af89f2 100644 > > > --- a/kernel/sched/sched.h > > > +++ b/kernel/sched/sched.h > > > @@ -2550,7 +2550,10 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, > > > > > > if (p) { > > > min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN)); > > > - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); > > > + if (rq->uclamp_flags & UCLAMP_FLAG_IDLE) > > > + max_util = uclamp_eff_value(p, UCLAMP_MAX); > > > + else > > > + max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX)); > > > > That makes sense to me - enqueuing the task will lift UCLAMP_FLAG_IDLE and > > set the rq clamp as the task's via uclamp_idle_reset(). > > > > Does this want a > > > > Fixes: 9d20ad7dfc9a ("sched/uclamp: Add uclamp_util_with()") > > > > ? > > Yes,add it. +1 > > > > > Also, when we have UCLAMP_FLAG_IDLE, we don't even need to read the rq max > > - and I'm pretty sure the same applies to the rq min. What about something like: uclamp_min is fine since it defaults to 0. But the suggested improvement looks good to me. Thanks -- Qais Yousef ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2021-06-30 14:11 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-06-18 7:23 [PATCH] sched/uclamp: Fix getting unreasonable ucalmp_max when rq is idle Xuewen Yan 2021-06-29 3:11 ` Xuewen Yan 2021-06-29 13:50 ` Valentin Schneider 2021-06-30 1:24 ` Xuewen Yan 2021-06-30 11:31 ` Valentin Schneider 2021-06-30 12:05 ` Xuewen Yan 2021-06-30 14:11 ` Qais Yousef
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