From: Peter Zijlstra <peterz@infradead.org>
To: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
Ingo Molnar <mingo@redhat.com>,
"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>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Juri Lelli <juri.lelli@redhat.com>, Todd Kjos <tkjos@android.com>,
Joel Fernandes <joelaf@google.com>,
Steve Muckle <smuckle@google.com>
Subject: Re: [PATCH v6 0/4] Utilization estimation (util_est) for FAIR tasks
Date: Fri, 16 Mar 2018 14:25:06 +0100 [thread overview]
Message-ID: <20180316132506.GF4064@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180309095245.11071-1-patrick.bellasi@arm.com>
On Fri, Mar 09, 2018 at 09:52:41AM +0000, Patrick Bellasi wrote:
> Hi, here is an update of [1], based on today's tip/sched/core [2], which mainly
> adds some code cleanups suggested by Peter as well as fixes compilation for
> !CONFIG_SMP systems.
>
> Most notably:
> a) The util_est's update flag has been renamed into UTIL_AVG_UNCHANGED, which
> seems to better match its usages.
> b) The cpu_util_est() function has been removed to reduce cluttering by folding
> its code directly into cpu_util(). This last function is thus now always
> returning the estimated utilization of a CPU, unless this sched feature is
> disabled.
> c) Not necessary READ_ONCE() have been removed from rq-lock protected code
> paths. For util_est variable, that we read/modify/write only from rq-lock
> protected, code we keep just the WRITE_ONCE() barriers, which are still
> required for synchronization with lockless readers.
> The READ_ONCE() have been instead maintained in all the getter functions,
> like for example task_util() and cpu_util(), which can potentially be used
> by lockless code. e.g. schedutil or load-balancer.
>
> Results on both x86_64 and ARM (Android) targets, which have been collected and
> reported in previous postings [1,3], show negligible overheads, especially
> compared to the corresponding power/performance benefits on mobile platforms,
> where this feature helps to reduce the performance gap between PELT and another
> other out-of-tree load tracking solution.
Thanks Patrick!
prev parent reply other threads:[~2018-03-16 13:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-09 9:52 [PATCH v6 0/4] Utilization estimation (util_est) for FAIR tasks Patrick Bellasi
2018-03-09 9:52 ` [PATCH v6 1/4] sched/fair: add util_est on top of PELT Patrick Bellasi
2018-03-20 11:07 ` [tip:sched/core] sched/fair: Add " tip-bot for Patrick Bellasi
2018-03-09 9:52 ` [PATCH v6 2/4] sched/fair: use util_est in LB and WU paths Patrick Bellasi
2018-03-20 11:08 ` [tip:sched/core] sched/fair: Use " tip-bot for Patrick Bellasi
2018-03-09 9:52 ` [PATCH v6 3/4] sched/cpufreq_schedutil: use util_est for OPP selection Patrick Bellasi
2018-03-20 11:08 ` [tip:sched/core] sched/cpufreq/schedutil: Use " tip-bot for Patrick Bellasi
2018-03-09 9:52 ` [PATCH v6 4/4] sched/fair: update util_est only on util_avg updates Patrick Bellasi
2018-03-20 11:09 ` [tip:sched/core] sched/fair: Update " tip-bot for Patrick Bellasi
2018-03-16 13:25 ` Peter Zijlstra [this message]
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