From: Patrick Bellasi <patrick.bellasi@arm.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-pm@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Paul Turner <pjt@google.com>,
Quentin Perret <quentin.perret@arm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Juri Lelli <juri.lelli@redhat.com>, Todd Kjos <tkjos@google.com>,
Joel Fernandes <joelaf@google.com>,
Steve Muckle <smuckle@google.com>
Subject: Re: [PATCH v4 02/16] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups
Date: Wed, 12 Sep 2018 11:32:01 +0100 [thread overview]
Message-ID: <20180912103201.GD1413@e110439-lin> (raw)
In-Reply-To: <CAJuCfpF36-VZm0JVVNnOnGm-ukVejzxbPhH33X3z9gAQ06t9gQ@mail.gmail.com>
Hi Suren,
On 08-Sep 16:47, Suren Baghdasaryan wrote:
[...]
> > + * A clamp group is not free if there is at least one SE which is sing a clamp
>
> typo in the sentence
Right, s/is sing/is using/
+1
[...]
> > +static int
> > +uclamp_group_find(int clamp_id, unsigned int clamp_value)
> > +{
> > + struct uclamp_map *uc_map = &uclamp_maps[clamp_id][0];
> > + int free_group_id = UCLAMP_NOT_VALID;
> > + unsigned int group_id = 0;
> > +
> > + for ( ; group_id <= CONFIG_UCLAMP_GROUPS_COUNT; ++group_id) {
> > + /* Keep track of first free clamp group */
> > + if (uclamp_group_available(clamp_id, group_id)) {
> > + if (free_group_id == UCLAMP_NOT_VALID)
> > + free_group_id = group_id;
> > + continue;
> > + }
>
> Not a big improvement but reordering the two conditions in this loop
> would avoid finding and recording free_group_id if the very first
> group is the one we are looking for.
Right, indeed with:
uclamp_group_put()
uclamp_group_reset()
uclamp_group_init()
we always ensure that:
uc_map[group_id].value == UCLAMP_NOT_VALID
for free groups. Thus, it should be safe to swap this two checks and
we likely save few instructions for a likely common case of non
clamped tasks.
+1
I'll also get the chance to remove the two simple comments. ;)
> > + /* Return index of first group with same clamp value */
> > + if (uc_map[group_id].value == clamp_value)
> > + return group_id;
> > + }
> > +
> > + if (likely(free_group_id != UCLAMP_NOT_VALID))
> > + return free_group_id;
> > +
> > + return -ENOSPC;
> > +}
[...]
> > +static inline void uclamp_group_put(int clamp_id, int group_id)
> Is the size and the number of invocations of this function small
> enough for inlining? Same goes for uclamp_group_get() and especially
> for __setscheduler_uclamp().
Right... yes, we could let the scheduler do its job and remove inline
from these functions... at least for those not in the critical path.
+1
[...]
> > + if (likely(uc_map[group_id].se_count))
> > + uc_map[group_id].se_count -= 1;
> > +#ifdef SCHED_DEBUG
> > + else {
>
> nit: no need for braces
>
> > + WARN(1, "invalid SE clamp group [%d:%d] refcount\n",
> > + clamp_id, group_id);
Since the above statement is multi-line, we actually need it for code
code-style requirements.
> > + }
> > +#endif
[...]
> > +static void uclamp_fork(struct task_struct *p, bool reset)
> > +{
> > + int clamp_id;
> > +
> > + if (unlikely(!p->sched_class->uclamp_enabled))
> > + return;
> > +
> > + for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) {
> > + int next_group_id = p->uclamp[clamp_id].group_id;
> > + struct uclamp_se *uc_se = &p->uclamp[clamp_id];
>
> Might be easier to read if after the above assignment you use
> uc_se->xxx instead of p->uclamp[clamp_id].xxx in the code below.
Yes, that's actually the intent of the above assigmenet... but I've
forgot a couple of usages! +1
> > +
> > + if (unlikely(reset)) {
> > + next_group_id = 0;
> > + p->uclamp[clamp_id].value = uclamp_none(clamp_id);
> > + }
> > +
> > + p->uclamp[clamp_id].group_id = UCLAMP_NOT_VALID;
> > + uclamp_group_get(clamp_id, next_group_id, uc_se,
> > + p->uclamp[clamp_id].value);
> > + }
> > +}
[...]
> Thanks,
> Suren.
Cheers,
Patrick
--
#include <best/regards.h>
Patrick Bellasi
next prev parent reply other threads:[~2018-09-12 10:32 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-28 13:53 [PATCH v4 00/16] Add utilization clamping support Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 01/16] sched/core: uclamp: extend sched_setattr to support utilization clamping Patrick Bellasi
2018-09-05 11:01 ` Juri Lelli
2018-08-28 13:53 ` [PATCH v4 02/16] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups Patrick Bellasi
2018-09-05 10:45 ` Juri Lelli
2018-09-06 13:48 ` Patrick Bellasi
2018-09-06 14:13 ` Juri Lelli
2018-09-06 8:17 ` Juri Lelli
2018-09-06 14:00 ` Patrick Bellasi
2018-09-08 23:47 ` Suren Baghdasaryan
2018-09-12 10:32 ` Patrick Bellasi [this message]
2018-09-12 13:49 ` Peter Zijlstra
2018-09-12 15:56 ` Patrick Bellasi
2018-09-12 16:12 ` Peter Zijlstra
2018-09-12 17:35 ` Patrick Bellasi
2018-09-12 17:42 ` Peter Zijlstra
2018-09-12 17:52 ` Patrick Bellasi
2018-09-13 19:14 ` Peter Zijlstra
2018-09-14 8:51 ` Patrick Bellasi
2018-09-12 16:24 ` Peter Zijlstra
2018-09-12 17:42 ` Patrick Bellasi
2018-09-13 19:20 ` Peter Zijlstra
2018-09-14 8:47 ` Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 03/16] sched/core: uclamp: add CPU's clamp groups accounting Patrick Bellasi
2018-09-12 17:34 ` Peter Zijlstra
2018-09-12 17:44 ` Patrick Bellasi
2018-09-13 19:12 ` Peter Zijlstra
2018-09-14 9:07 ` Patrick Bellasi
2018-09-14 11:52 ` Peter Zijlstra
2018-09-14 13:41 ` Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 04/16] sched/core: uclamp: update CPU's refcount on clamp changes Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 05/16] sched/core: uclamp: enforce last task UCLAMP_MAX Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 06/16] sched/cpufreq: uclamp: add utilization clamping for FAIR tasks Patrick Bellasi
2018-09-14 9:32 ` Peter Zijlstra
2018-09-14 13:19 ` Patrick Bellasi
2018-09-14 13:36 ` Peter Zijlstra
2018-09-14 13:57 ` Patrick Bellasi
2018-09-27 10:23 ` Quentin Perret
2018-08-28 13:53 ` [PATCH v4 07/16] sched/core: uclamp: extend cpu's cgroup controller Patrick Bellasi
2018-08-28 18:29 ` Randy Dunlap
2018-08-29 8:53 ` Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 08/16] sched/core: uclamp: propagate parent clamps Patrick Bellasi
2018-09-09 3:02 ` Suren Baghdasaryan
2018-09-12 12:51 ` Patrick Bellasi
2018-09-12 15:56 ` Suren Baghdasaryan
2018-09-11 15:18 ` Tejun Heo
2018-09-11 16:26 ` Patrick Bellasi
2018-09-11 16:28 ` Tejun Heo
2018-08-28 13:53 ` [PATCH v4 09/16] sched/core: uclamp: map TG's clamp values into CPU's clamp groups Patrick Bellasi
2018-09-09 18:52 ` Suren Baghdasaryan
2018-09-12 14:19 ` Patrick Bellasi
2018-09-12 15:53 ` Suren Baghdasaryan
2018-08-28 13:53 ` [PATCH v4 10/16] sched/core: uclamp: use TG's clamps to restrict Task's clamps Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 11/16] sched/core: uclamp: add system default clamps Patrick Bellasi
2018-09-10 16:20 ` Suren Baghdasaryan
2018-09-11 16:46 ` Patrick Bellasi
2018-09-11 19:25 ` Suren Baghdasaryan
2018-08-28 13:53 ` [PATCH v4 12/16] sched/core: uclamp: update CPU's refcount on TG's clamp changes Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 13/16] sched/core: uclamp: use percentage clamp values Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 14/16] sched/core: uclamp: request CAP_SYS_ADMIN by default Patrick Bellasi
2018-09-04 13:47 ` Juri Lelli
2018-09-06 14:40 ` Patrick Bellasi
2018-09-06 14:59 ` Juri Lelli
2018-09-06 17:21 ` Patrick Bellasi
2018-09-14 11:10 ` Peter Zijlstra
2018-09-14 14:07 ` Patrick Bellasi
2018-09-14 14:28 ` Peter Zijlstra
2018-09-17 12:27 ` Patrick Bellasi
2018-09-21 9:13 ` Peter Zijlstra
2018-09-24 15:14 ` Patrick Bellasi
2018-09-24 15:56 ` Peter Zijlstra
2018-09-24 17:23 ` Patrick Bellasi
2018-09-24 16:26 ` Peter Zijlstra
2018-09-24 17:19 ` Patrick Bellasi
2018-09-25 15:49 ` Peter Zijlstra
2018-09-26 10:43 ` Patrick Bellasi
2018-09-27 10:00 ` Quentin Perret
2018-09-26 17:51 ` Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 15/16] sched/core: uclamp: add clamp group discretization support Patrick Bellasi
2018-08-28 13:53 ` [PATCH v4 16/16] sched/cpufreq: uclamp: add utilization clamping for RT tasks Patrick Bellasi
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