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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Rafael Wysocki <rjw@rjwysocki.net>,
	Ben Segall <bsegall@google.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>, Mel Gorman <mgorman@suse.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-pm@vger.kernel.org, Lukasz Luba <lukasz.luba@arm.com>,
	cristian.marussi@arm.com, sudeep.holla@arm.com,
	linux-kernel@vger.kernel.org
Subject: [PATCH V3 0/5] cpufreq: Record stats with fast-switching
Date: Mon,  5 Oct 2020 13:26:00 +0530	[thread overview]
Message-ID: <cover.1601884370.git.viresh.kumar@linaro.org> (raw)

Hi,

We disabled recording cpufreq stats when fast switching was introduced
to the cpufreq core as the cpufreq stats required to take a spinlock and
that can't be allowed (for performance reasons) on scheduler's hot path.

Here is an attempt to get rid of the lock and bring back the support.

V2->V3:
- Use READ/WRITE_ONCE() for reset-time as well.
- Use unlikely for few conditionals in the hot path.
- Better changelogs.
- Rebase changes.

V1-V2:
- Use READ_ONCE/WRITE_ONCE instead of atomic in the first patch.

--
Viresh

Viresh Kumar (5):
  cpufreq: stats: Defer stats update to
    cpufreq_stats_record_transition()
  cpufreq: stats: Remove locking
  cpufreq: stats: Mark few conditionals with unlikely()
  cpufreq: stats: Enable stats for fast-switch as well
  cpufreq: Move traces and update to policy->cur to cpufreq core

 drivers/cpufreq/cpufreq.c        | 11 ++++
 drivers/cpufreq/cpufreq_stats.c  | 89 ++++++++++++++++++++------------
 kernel/sched/cpufreq_schedutil.c | 12 +----
 3 files changed, 69 insertions(+), 43 deletions(-)

-- 
2.25.0.rc1.19.g042ed3e048af


             reply	other threads:[~2020-10-05  7:56 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-05  7:56 Viresh Kumar [this message]
2020-10-05  7:56 ` [PATCH V3 1/5] cpufreq: stats: Defer stats update to cpufreq_stats_record_transition() Viresh Kumar
2020-10-05  7:56 ` [PATCH V3 2/5] cpufreq: stats: Remove locking Viresh Kumar
2020-10-05  7:56 ` [PATCH V3 3/5] cpufreq: stats: Mark few conditionals with unlikely() Viresh Kumar
2020-10-05  7:56 ` [PATCH V3 4/5] cpufreq: stats: Enable stats for fast-switch as well Viresh Kumar
2020-10-05  7:56 ` [PATCH V3 5/5] cpufreq: Move traces and update to policy->cur to cpufreq core Viresh Kumar
2020-10-05 13:25 ` [PATCH V3 0/5] cpufreq: Record stats with fast-switching Rafael J. Wysocki

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