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From: Qais Yousef <qais.yousef@arm.com>
To: Xuewen Yan <xuewen.yan94@gmail.com>
Cc: Quentin Perret <qperret@google.com>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Benjamin Segall <bsegall@google.com>,
	Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Chunyan Zhang <zhang.lyra@gmail.com>,
	Ryan Y <xuewyan@foxmail.com>,
	Patrick Bellasi <patrick.bellasi@matbug.net>,
	tj@kernel.org
Subject: Re: [PATCH] sched/uclamp: Avoid setting cpu.uclamp.min bigger than cpu.uclamp.max
Date: Tue, 8 Jun 2021 19:21:57 +0100	[thread overview]
Message-ID: <20210608182157.lx6ypd6sm6gwxkt4@e107158-lin.cambridge.arm.com> (raw)
In-Reply-To: <CAB8ipk_w9JeFmbjSOFR-GnaPNiAoFt8f30Oxh3fZRw58wDXo4w@mail.gmail.com>

On 06/08/21 23:01, Xuewen Yan wrote:
> Hi
> 
> On Tue, Jun 8, 2021 at 10:25 PM Qais Yousef <qais.yousef@arm.com> wrote:
> >
> > --->8---
> >
> > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > index 9e9a5be35cde..1d2d3e6648a6 100644
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -1403,38 +1403,28 @@ static void uclamp_sync_util_min_rt_default(void)
> >  static inline struct uclamp_se
> >  uclamp_tg_restrict(struct task_struct *p, enum uclamp_id clamp_id)
> >  {
> > -       struct uclamp_se uc_req = p->uclamp_req[clamp_id];
> > +       /* Copy by value as we could modify it */
> > +       struct uclamp_se uc_eff = p->uclamp_req[clamp_id];
> >  #ifdef CONFIG_UCLAMP_TASK_GROUP
> > +       unsigned long tg_min, tg_max, value;
> >
> >         /*
> >          * Tasks in autogroups or root task group will be
> >          * restricted by system defaults.
> >          */
> >         if (task_group_is_autogroup(task_group(p)))
> > -               return uc_req;
> > +               return uc_eff;
> >         if (task_group(p) == &root_task_group)
> > -               return uc_req;
> > +               return uc_eff;
> >
> > -       switch (clamp_id) {
> > -       case UCLAMP_MIN: {
> > -               struct uclamp_se uc_min = task_group(p)->uclamp[clamp_id];
> > -               if (uc_req.value < uc_min.value)
> > -                       return uc_min;
> > -               break;
> > -       }
> > -       case UCLAMP_MAX: {
> > -               struct uclamp_se uc_max = task_group(p)->uclamp[clamp_id];
> > -               if (uc_req.value > uc_max.value)
> > -                       return uc_max;
> > -               break;
> > -       }
> > -       default:
> > -               WARN_ON_ONCE(1);
> > -               break;
> > -       }
> > +       tg_min = task_group(p)->uclamp[UCLAMP_MIN].value;
> > +       tg_max = task_group(p)->uclamp[UCLAMP_MAX].value;
> > +       value = uc_eff.value;
> > +       value = clamp(value, tg_min, tg_max);
> > +       uclamp_se_set(&uc_eff, value, false);
> 
> Is it reasonable to set user_defined to be false here?

Yep, it doesn't really matter for the effective value. It matters for the
actual task request.

> 
> >  #endif
> >
> > -       return uc_req;
> > +       return uc_eff;
> >  }
> >
> >  /*
> > @@ -1661,8 +1651,7 @@ uclamp_update_active(struct task_struct *p, enum uclamp_id clamp_id)
> >
> >  #ifdef CONFIG_UCLAMP_TASK_GROUP
> >  static inline void
> > -uclamp_update_active_tasks(struct cgroup_subsys_state *css,
> > -                          unsigned int clamps)
> > +uclamp_update_active_tasks(struct cgroup_subsys_state *css)
> >  {
> >         enum uclamp_id clamp_id;
> >         struct css_task_iter it;
> > @@ -1670,10 +1659,8 @@ uclamp_update_active_tasks(struct cgroup_subsys_state *css,
> >
> >         css_task_iter_start(css, 0, &it);
> >         while ((p = css_task_iter_next(&it))) {
> > -               for_each_clamp_id(clamp_id) {
> > -                       if ((0x1 << clamp_id) & clamps)
> > -                               uclamp_update_active(p, clamp_id);
> > -               }
> > +               for_each_clamp_id(clamp_id)
> > +                       uclamp_update_active(p, clamp_id);
> >         }
> >         css_task_iter_end(&it);
> >  }
> > @@ -9626,7 +9613,7 @@ static void cpu_util_update_eff(struct cgroup_subsys_state *css)
> >                 }
> >
> >                 /* Immediately update descendants RUNNABLE tasks */
> > -               uclamp_update_active_tasks(css, clamps);
> > +               uclamp_update_active_tasks(css);
> >         }
> >  }
> 
> Would you resend another email? maybe it would be better to resend an
> email with a new subject?

Yeah I will do a proper posting. But I need to stare at this a bit more then
will do.

Thanks

--
Qais Yousef

      reply	other threads:[~2021-06-08 18:22 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-02 12:38 Xuewen Yan
2021-06-02 13:22 ` Quentin Perret
2021-06-03  2:24   ` Xuewen Yan
2021-06-04 16:08     ` Qais Yousef
2021-06-04 16:22       ` Dietmar Eggemann
2021-06-05  2:14         ` Xuewen Yan
2021-06-05  2:12       ` Xuewen Yan
2021-06-05 11:49         ` Qais Yousef
2021-06-05 13:24           ` Xuewen Yan
2021-06-05 14:14             ` Qais Yousef
2021-06-07 13:49             ` Qais Yousef
2021-06-08 11:45               ` Xuewen Yan
2021-06-08 14:25                 ` Qais Yousef
2021-06-08 15:01                   ` Xuewen Yan
2021-06-08 18:21                     ` Qais Yousef [this message]

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