From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Vincent Guittot <vincent.guittot@linaro.org>,
linux-kernel@vger.kernel.org, mingo@redhat.com,
peterz@infradead.org, juri.lelli@redhat.com, rostedt@goodmis.org,
mgorman@suse.de, dsmythies@telus.net
Cc: linux-pm@vger.kernel.org, torvalds@linux-foundation.org,
tglx@linutronix.de, sargun@sargun.me, tj@kernel.org,
xiexiuqi@huawei.com, xiezhipeng1@huawei.com,
srinivas.pandruvada@linux.intel.com
Subject: Re: [PATCH v2] sched/freq: move call to cpufreq_update_util
Date: Wed, 13 Nov 2019 11:49:57 +0100 [thread overview]
Message-ID: <3b8cafb7-894d-c302-e6c6-b5844b1298b5@arm.com> (raw)
In-Reply-To: <20191112150544.GA3664@linaro.org>
On 12.11.19 16:05, Vincent Guittot wrote:
> Le Tuesday 12 Nov 2019 à 15:48:13 (+0100), Vincent Guittot a écrit :
>> update_cfs_rq_load_avg() calls cfs_rq_util_change() everytime pelt decays,
>> which might be inefficient when cpufreq driver has rate limitation.
>>
>> When a task is attached on a CPU, we have call path:
>>
>> update_blocked_averages()
>> update_cfs_rq_load_avg()
>> cfs_rq_util_change -- > trig frequency update
>> attach_entity_load_avg()
>> cfs_rq_util_change -- > trig frequency update
This looks like attach_entity_load_avg() is called from
update_blocked_averages(). Do you refer to the attach_entity_load_avg()
call from attach_entity_cfs_rq() or update_load_avg() here? I assume the
former.
>> The 1st frequency update will not take into account the utilization of the
>> newly attached task and the 2nd one might be discard because of rate
>> limitation of the cpufreq driver.
>>
>> update_cfs_rq_load_avg() is only called by update_blocked_averages()
>> and update_load_avg() so we can move the call to
>> {cfs_rq,cpufreq}_util_change() into these 2 functions. It's also
s/cpufreq_util_change()/cpufreq_update_util() ?
[...]
>> I have just rebased the patch on latest tip/sched/core and made it a proper
>> patchset after Doug reported that the problem has diseappeared according to
>> his 1st results but tests results are not all based on the same v5.4-rcX
>> and with menu instead of teo governor.
I had some minor tweaks to do putting this on a0e813f26ebc ("sched/core:
Further clarify sched_class::set_next_task()") ? I saw the '[tip:
sched/urgent] sched/pelt: Fix update of blocked PELT ordering' tip-bot
msg this morning though.
[...]
>> @@ -7493,9 +7495,9 @@ static void update_blocked_averages(int cpu)
>> * that RT, DL and IRQ signals have been updated before updating CFS.
>> */
>> curr_class = rq->curr->sched_class;
>> - update_rt_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &rt_sched_class);
>> - update_dl_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &dl_sched_class);
>> - update_irq_load_avg(rq, 0);
>> + decayed |= update_rt_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &rt_sched_class);
>> + decayed |= update_dl_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &dl_sched_class);
>> + decayed |= update_irq_load_avg(rq, 0);
Why not 'decayed = update_cfs_rq_load_avg()' like in the
!CONFIG_FAIR_GROUP_SCHED case?
[...]
next prev parent reply other threads:[~2019-11-13 10:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1573570093-1340-1-git-send-email-vincent.guittot@linaro.org>
2019-11-12 15:05 ` [PATCH v2] sched/freq: move call to cpufreq_update_util Vincent Guittot
2019-11-12 17:11 ` Valentin Schneider
2019-11-12 17:20 ` Vincent Guittot
2019-11-12 17:44 ` Valentin Schneider
2019-11-13 10:49 ` Dietmar Eggemann [this message]
2019-11-13 13:30 ` Vincent Guittot
2019-11-13 14:09 ` Dietmar Eggemann
2019-11-13 17:50 ` Vincent Guittot
2019-11-13 18:09 ` Vincent Guittot
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