From: Xuewen Yan <xuewen.yan94@gmail.com>
To: Qais Yousef <qais.yousef@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
linux-kernel@vger.kernel.org, Wei Wang <wvw@google.com>,
Jonathan JMChen <Jonathan.JMChen@mediatek.com>,
Hank <han.lin@mediatek.com>
Subject: Re: [PATCH 7/7] sched/uclamp: Cater for uclamp in find_energy_efficient_cpu()'s early exit condition
Date: Fri, 22 Jul 2022 09:09:59 +0800 [thread overview]
Message-ID: <CAB8ipk_-t_iMicZ2+u=H16XiHtnpccPLse=+UQN9pv7d78sU+A@mail.gmail.com> (raw)
In-Reply-To: <20220721142447.emsv6q3y4ch3bphi@wubuntu>
On Thu, Jul 21, 2022 at 10:24 PM Qais Yousef <qais.yousef@arm.com> wrote:
>
> On 07/20/22 15:39, Xuewen Yan wrote:
> > Hi Qais
> >
> > On Thu, Jun 30, 2022 at 3:48 AM Qais Yousef <qais.yousef@arm.com> wrote:
> > >
> > > If the utilization of the woken up task is 0, we skip the energy
> > > calculation because it has no impact.
> > >
> > > But if the task is boosted (uclamp_min != 0) will have an impact on task
> > > placement and frequency selection. Only skip if the util is truly
> > > 0 after applying uclamp values.
> > >
> > > Change uclamp_task_cpu() signature to avoid unnecessary additional calls
> > > to uclamp_eff_get(). feec() is the only user now.
> > >
> > > Fixes: 732cd75b8c920 ("sched/fair: Select an energy-efficient CPU on task wake-up")
> > > Signed-off-by: Qais Yousef <qais.yousef@arm.com>
> > > ---
> > > kernel/sched/fair.c | 14 ++++++++------
> > > 1 file changed, 8 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > > index 499ef7a7288c..a112ca45864c 100644
> > > --- a/kernel/sched/fair.c
> > > +++ b/kernel/sched/fair.c
> > > @@ -4057,14 +4057,16 @@ static inline unsigned long task_util_est(struct task_struct *p)
> > > }
> > >
> > > #ifdef CONFIG_UCLAMP_TASK
> > > -static inline unsigned long uclamp_task_util(struct task_struct *p)
> > > +static inline unsigned long uclamp_task_util(struct task_struct *p,
> > > + unsigned long uclamp_min,
> > > + unsigned long uclamp_max)
> > > {
> > > - return clamp(task_util_est(p),
> > > - uclamp_eff_value(p, UCLAMP_MIN),
> > > - uclamp_eff_value(p, UCLAMP_MAX));
> > > + return clamp(task_util_est(p), uclamp_min, uclamp_max);
> > > }
> > > #else
> > > -static inline unsigned long uclamp_task_util(struct task_struct *p)
> > > +static inline unsigned long uclamp_task_util(struct task_struct *p,
> > > + unsigned long uclamp_min,
> > > + unsigned long uclamp_max)
> > > {
> > > return task_util_est(p);
> > > }
> > > @@ -6913,7 +6915,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
> > > target = prev_cpu;
> > >
> > > sync_entity_load_avg(&p->se);
> > > - if (!task_util_est(p))
> > > + if (!uclamp_task_util(p, p_util_min, p_util_max))
> >
> > Is it not enough to just replace the task_util_est with the
> > uclamp_task_util? If change the definition of uclamp_task_util,
> > that means it have to get task's uclamp first if user want to call the
> > function, may increase the code complex farther more?
>
> Calling uclamp_eff_value() all the time is not cheap actually.
>
> We can easily add two versions when we need to:
>
> __uclamp_task_util(p, uclamp_min, uclamp_max);
>
> uclamp_task_util(p) {
> uclamp_min = uclamp_eff_value();
> uclamp_max = uclamp_eff_value();
> return __uclamp_eff_value(p, uclamp_min, uclamp_max);
> }
>
> When we need to. Since we have a single user now, there's no need to do this
> now and if we ever get more users it'd be easy to refactor then?
Sounds good!
Thanks!
>
>
> Thanks!
>
> --
> Qais Yousef
>
> >
> > > goto unlock;
> > >
> > > for (; pd; pd = pd->next) {
> > > --
> > > 2.25.1
> > >
> >
> > BR
> > ---
> > xuewen.yan
prev parent reply other threads:[~2022-07-22 1:10 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-29 19:46 [PATCH 0/7] Fix relationship between uclamp and fits_capacity() Qais Yousef
2022-06-29 19:46 ` [PATCH 1/7] sched/uclamp: Fix relationship between uclamp and migration margin Qais Yousef
2022-07-11 12:36 ` Vincent Guittot
2022-07-12 10:23 ` Qais Yousef
2022-07-12 13:21 ` Vincent Guittot
2022-07-12 14:20 ` Qais Yousef
2022-07-13 12:39 ` Vincent Guittot
2022-07-15 10:37 ` Qais Yousef
2022-07-20 7:29 ` Vincent Guittot
2022-07-21 14:04 ` Qais Yousef
2022-07-22 15:13 ` Vincent Guittot
2022-07-27 16:08 ` Qais Yousef
2022-08-04 14:59 ` Qais Yousef
2022-07-20 7:17 ` Xuewen Yan
2022-07-21 10:24 ` Qais Yousef
2022-07-25 11:59 ` Xuewen Yan
2022-07-27 16:25 ` Qais Yousef
2022-08-01 2:46 ` Xuewen Yan
2022-08-02 16:22 ` Qais Yousef
2022-06-29 19:46 ` [PATCH 2/7] sched/uclamp: Make task_fits_capacity() use util_fits_cpu() Qais Yousef
2022-07-11 13:09 ` Vincent Guittot
2022-07-12 10:48 ` Qais Yousef
2022-07-21 14:29 ` Qais Yousef
2022-07-22 8:19 ` Vincent Guittot
2022-07-27 16:05 ` Qais Yousef
2022-08-17 9:48 ` Vincent Guittot
2022-07-20 7:23 ` Xuewen Yan
2022-07-21 14:11 ` Qais Yousef
2022-06-29 19:46 ` [PATCH 3/7] sched/uclamp: Fix fits_capacity() check in feec() Qais Yousef
2022-07-20 7:30 ` Xuewen Yan
2022-07-21 14:19 ` Qais Yousef
2022-06-29 19:46 ` [PATCH 4/7] sched/uclamp: Make select_idle_capacity() use util_fits_cpu() Qais Yousef
2022-06-29 19:46 ` [PATCH 5/7] sched/uclamp: Make asym_fits_capacity() " Qais Yousef
2022-06-29 19:46 ` [PATCH 6/7] sched/uclamp: Make cpu_overutilized() " Qais Yousef
2022-06-29 19:46 ` [PATCH 7/7] sched/uclamp: Cater for uclamp in find_energy_efficient_cpu()'s early exit condition Qais Yousef
2022-07-20 7:39 ` Xuewen Yan
2022-07-21 14:24 ` Qais Yousef
2022-07-22 1:09 ` Xuewen Yan [this message]
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