linux-kernel - [PATCH V3 0/5] cpufreq: Record stats with fast-switching

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Message-Id: <cover.1601884370.git.viresh.kumar@linaro.org>
Date:   Mon,  5 Oct 2020 13:26:00 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rafael Wysocki <rjw@...ysocki.net>,
        Ben Segall <bsegall@...gle.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Mel Gorman <mgorman@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Cc:     linux-pm@...r.kernel.org, Lukasz Luba <lukasz.luba@....com>,
        cristian.marussi@....com, sudeep.holla@....com,
        linux-kernel@...r.kernel.org
Subject: [PATCH V3 0/5] cpufreq: Record stats with fast-switching

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