From: Viresh Kumar <viresh.kumar@linaro.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Linux PM list <linux-pm@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@arm.com>,
Steve Muckle <steve.muckle@linaro.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Michael Turquette <mturquette@baylibre.com>
Subject: Re: [PATCH 1/6] cpufreq: Reduce cpufreq_update_util() overhead a bit
Date: Thu, 3 Mar 2016 11:18:38 +0530 [thread overview]
Message-ID: <20160303054838.GH2891@vireshk-i7> (raw)
In-Reply-To: <3575770.L1lplNLqVv@vostro.rjw.lan>
On 02-03-16, 03:04, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Use the observation that cpufreq_update_util() is only called
> by the scheduler with rq->lock held, so the callers of
> cpufreq_set_update_util_data() can use synchronize_sched()
> instead of synchronize_rcu() to wait for cpufreq_update_util()
> to complete. Moreover, if they are updated to do that,
> rcu_read_(un)lock() calls in cpufreq_update_util() might be
> replaced with rcu_read_(un)lock_sched(), respectively, but
> those aren't really necessary, because the scheduler calls
> that function from RCU-sched read-side critical sections
> already.
>
> In addition to that, if cpufreq_set_update_util_data() checks
> the func field in the struct update_util_data before setting
> the per-CPU pointer to it, the data->func check may be dropped
> from cpufreq_update_util() as well.
>
> Make the above changes to reduce the overhead from
> cpufreq_update_util() in the scheduler paths invoking it
> and to make the cleanup after removing its callbacks less
> heavy-weight somewhat.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>
> Supersedes https://patchwork.kernel.org/patch/8443191/
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
--
viresh
next prev parent reply other threads:[~2016-03-03 5:48 UTC|newest]
Thread overview: 159+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-02 1:56 [PATCH 0/6] cpufreq: schedutil governor Rafael J. Wysocki
2016-03-02 2:04 ` [PATCH 1/6] cpufreq: Reduce cpufreq_update_util() overhead a bit Rafael J. Wysocki
2016-03-03 5:48 ` Viresh Kumar [this message]
2016-03-03 11:47 ` Juri Lelli
2016-03-03 13:04 ` Peter Zijlstra
2016-03-02 2:05 ` [PATCH 2/6][Resend] cpufreq: acpi-cpufreq: Make read and write operations more efficient Rafael J. Wysocki
2016-03-02 2:08 ` [PATCH 3/6] cpufreq: governor: New data type for management part of dbs_data Rafael J. Wysocki
2016-03-03 5:53 ` Viresh Kumar
2016-03-03 19:26 ` Rafael J. Wysocki
2016-03-04 5:49 ` Viresh Kumar
2016-03-02 2:10 ` [PATCH 4/6] cpufreq: governor: Move abstract gov_tunables code to a seperate file Rafael J. Wysocki
2016-03-03 6:03 ` Viresh Kumar
2016-03-02 2:12 ` [PATCH 5/6] cpufreq: Support for fast frequency switching Rafael J. Wysocki
2016-03-03 6:00 ` Viresh Kumar
2016-03-04 2:15 ` Rafael J. Wysocki
2016-03-03 11:16 ` Peter Zijlstra
2016-03-03 20:56 ` Rafael J. Wysocki
2016-03-03 21:12 ` Peter Zijlstra
2016-03-03 11:18 ` Peter Zijlstra
2016-03-03 19:39 ` Rafael J. Wysocki
2016-03-02 2:27 ` [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Rafael J. Wysocki
2016-03-02 17:10 ` Vincent Guittot
2016-03-02 17:58 ` Rafael J. Wysocki
2016-03-02 22:49 ` Rafael J. Wysocki
2016-03-03 12:20 ` Peter Zijlstra
2016-03-03 12:32 ` Juri Lelli
2016-03-03 16:24 ` Rafael J. Wysocki
2016-03-03 16:37 ` Peter Zijlstra
2016-03-03 16:47 ` Peter Zijlstra
2016-03-04 1:14 ` Rafael J. Wysocki
2016-03-03 16:55 ` Juri Lelli
2016-03-03 16:56 ` Peter Zijlstra
2016-03-03 17:14 ` Juri Lelli
2016-03-03 14:01 ` Vincent Guittot
2016-03-03 15:38 ` Peter Zijlstra
2016-03-03 16:28 ` Peter Zijlstra
2016-03-03 16:42 ` Peter Zijlstra
2016-03-03 17:28 ` Dietmar Eggemann
2016-03-03 18:26 ` Peter Zijlstra
2016-03-03 19:14 ` Dietmar Eggemann
2016-03-08 13:09 ` Peter Zijlstra
2016-03-03 18:58 ` Rafael J. Wysocki
2016-03-03 13:07 ` Vincent Guittot
2016-03-03 20:06 ` Steve Muckle
2016-03-03 20:20 ` Rafael J. Wysocki
2016-03-03 21:37 ` Steve Muckle
2016-03-07 2:41 ` Rafael J. Wysocki
2016-03-08 11:27 ` Peter Zijlstra
2016-03-08 18:00 ` Rafael J. Wysocki
2016-03-08 19:26 ` Peter Zijlstra
2016-03-08 20:05 ` Rafael J. Wysocki
2016-03-09 10:15 ` Juri Lelli
2016-03-09 23:41 ` Rafael J. Wysocki
2016-03-10 4:30 ` Juri Lelli
2016-03-10 21:01 ` Rafael J. Wysocki
2016-03-10 23:19 ` Michael Turquette
2016-03-10 23:19 ` Michael Turquette
2016-03-09 16:39 ` Peter Zijlstra
2016-03-09 23:28 ` Rafael J. Wysocki
2016-03-10 3:44 ` Vincent Guittot
2016-03-10 10:07 ` Peter Zijlstra
2016-03-10 10:26 ` Vincent Guittot
[not found] ` <CAKfTPtCbjgbJn+68NJPCnmPFtcHD0wGmZRYaw37zSqPXNpo_Uw@mail.gmail.com>
2016-03-10 10:30 ` Peter Zijlstra
2016-03-10 10:56 ` Peter Zijlstra
2016-03-10 22:28 ` Rafael J. Wysocki
2016-03-10 8:43 ` Peter Zijlstra
2016-03-04 2:56 ` [PATCH v2 0/10] cpufreq: schedutil governor Rafael J. Wysocki
2016-03-04 2:58 ` [PATCH v2 1/10] cpufreq: Reduce cpufreq_update_util() overhead a bit Rafael J. Wysocki
2016-03-09 12:39 ` Peter Zijlstra
2016-03-09 14:17 ` Rafael J. Wysocki
2016-03-09 15:29 ` Peter Zijlstra
2016-03-09 21:35 ` Rafael J. Wysocki
2016-03-10 9:19 ` Peter Zijlstra
2016-03-04 2:59 ` [PATCH v2 2/10][Resend] cpufreq: acpi-cpufreq: Make read and write operations more efficient Rafael J. Wysocki
2016-03-04 3:01 ` [PATCH v2 3/10] cpufreq: governor: New data type for management part of dbs_data Rafael J. Wysocki
2016-03-04 5:52 ` Viresh Kumar
2016-03-04 3:03 ` [PATCH v2 4/10] cpufreq: governor: Move abstract gov_attr_set code to seperate file Rafael J. Wysocki
2016-03-04 5:52 ` Viresh Kumar
2016-03-04 3:05 ` [PATCH v2 5/10] cpufreq: Move governor attribute set headers to cpufreq.h Rafael J. Wysocki
2016-03-04 5:53 ` Viresh Kumar
2016-03-04 3:07 ` [PATCH v2 6/10] cpufreq: Support for fast frequency switching Rafael J. Wysocki
2016-03-04 22:18 ` Steve Muckle
2016-03-04 22:32 ` Rafael J. Wysocki
2016-03-04 22:40 ` Rafael J. Wysocki
2016-03-04 23:18 ` Rafael J. Wysocki
2016-03-04 23:56 ` Steve Muckle
2016-03-05 0:18 ` Rafael J. Wysocki
2016-03-05 11:58 ` Ingo Molnar
2016-03-05 16:49 ` Peter Zijlstra
2016-03-06 2:17 ` Rafael J. Wysocki
2016-03-07 8:00 ` Peter Zijlstra
2016-03-07 13:15 ` Rafael J. Wysocki
2016-03-07 13:32 ` Peter Zijlstra
2016-03-07 13:42 ` Rafael J. Wysocki
2016-03-04 22:58 ` Rafael J. Wysocki
2016-03-04 23:59 ` Steve Muckle
2016-03-04 3:12 ` [PATCH v2 7/10] cpufreq: Rework the scheduler hooks for triggering updates Rafael J. Wysocki
2016-03-04 3:14 ` [PATCH v2 8/10] cpufreq: Move scheduler-related code to the sched directory Rafael J. Wysocki
2016-03-04 3:18 ` [PATCH v2 9/10] cpufreq: sched: Re-introduce cpufreq_update_util() Rafael J. Wysocki
2016-03-04 10:50 ` Juri Lelli
2016-03-04 12:58 ` Rafael J. Wysocki
2016-03-04 13:30 ` [PATCH v3 " Rafael J. Wysocki
2016-03-04 21:21 ` Steve Muckle
2016-03-04 21:27 ` Rafael J. Wysocki
2016-03-04 21:36 ` Rafael J. Wysocki
2016-03-04 3:35 ` [PATCH v2 10/10] cpufreq: schedutil: New governor based on scheduler utilization data Rafael J. Wysocki
2016-03-04 11:26 ` Juri Lelli
2016-03-04 13:19 ` Rafael J. Wysocki
2016-03-04 15:56 ` Srinivas Pandruvada
2016-03-08 2:23 ` [PATCH v3 0/7] cpufreq: schedutil governor Rafael J. Wysocki
2016-03-08 2:25 ` [PATCH v3 1/7][Resend] cpufreq: Rework the scheduler hooks for triggering updates Rafael J. Wysocki
2016-03-09 13:41 ` Peter Zijlstra
2016-03-09 14:02 ` Rafael J. Wysocki
2016-03-08 2:26 ` [PATCH v3 2/7][Resend] cpufreq: Move scheduler-related code to the sched directory Rafael J. Wysocki
2016-03-08 2:28 ` [PATCH v3 3/7][Resend] cpufreq: governor: New data type for management part of dbs_data Rafael J. Wysocki
2016-03-08 2:29 ` [PATCH v3 4/7][Resend] cpufreq: governor: Move abstract gov_attr_set code to seperate file Rafael J. Wysocki
2016-03-08 2:38 ` [PATCH v3 5/7] cpufreq: Support for fast frequency switching Rafael J. Wysocki
2016-03-08 2:41 ` [PATCH v3 6/7] cpufreq: sched: Re-introduce cpufreq_update_util() Rafael J. Wysocki
2016-03-08 2:50 ` [PATCH v3 7/7] cpufreq: schedutil: New governor based on scheduler utilization data Rafael J. Wysocki
2016-03-16 14:41 ` [PATCH v4 0/7] cpufreq: schedutil governor Rafael J. Wysocki
2016-03-16 14:43 ` [PATCH v4 1/7] cpufreq: sched: Helpers to add and remove update_util hooks Rafael J. Wysocki
2016-03-16 14:44 ` [PATCH v4 2/7] cpufreq: governor: New data type for management part of dbs_data Rafael J. Wysocki
2016-03-16 14:45 ` [PATCH v4 3/7] cpufreq: governor: Move abstract gov_attr_set code to seperate file Rafael J. Wysocki
2016-03-16 14:46 ` [PATCH v4 4/7] cpufreq: Move governor attribute set headers to cpufreq.h Rafael J. Wysocki
2016-03-16 14:47 ` [PATCH v4 5/7] cpufreq: Move governor symbols " Rafael J. Wysocki
2016-03-16 14:52 ` [PATCH v4 6/7] cpufreq: Support for fast frequency switching Rafael J. Wysocki
2016-03-16 15:35 ` Peter Zijlstra
2016-03-16 16:58 ` Rafael J. Wysocki
2016-03-16 15:43 ` Peter Zijlstra
2016-03-16 16:58 ` Rafael J. Wysocki
2016-03-16 14:59 ` [PATCH v4 7/7] cpufreq: schedutil: New governor based on scheduler utilization data Rafael J. Wysocki
2016-03-16 17:35 ` Peter Zijlstra
2016-03-16 21:42 ` Rafael J. Wysocki
2016-03-16 17:36 ` Peter Zijlstra
2016-03-16 21:34 ` Rafael J. Wysocki
2016-03-16 17:52 ` Peter Zijlstra
2016-03-16 21:38 ` Rafael J. Wysocki
2016-03-16 22:39 ` Peter Zijlstra
2016-03-16 17:53 ` Peter Zijlstra
2016-03-16 21:48 ` Rafael J. Wysocki
2016-03-16 18:14 ` Peter Zijlstra
2016-03-16 21:38 ` Rafael J. Wysocki
2016-03-16 22:40 ` Peter Zijlstra
2016-03-16 22:53 ` Rafael J. Wysocki
2016-03-16 15:27 ` [PATCH v4 0/7] cpufreq: schedutil governor Peter Zijlstra
2016-03-16 16:20 ` Rafael J. Wysocki
2016-03-16 23:51 ` [PATCH v5 6/7][Update] cpufreq: Support for fast frequency switching Rafael J. Wysocki
2016-03-17 11:35 ` Juri Lelli
2016-03-17 11:40 ` Peter Zijlstra
2016-03-17 11:48 ` Juri Lelli
2016-03-17 12:53 ` Rafael J. Wysocki
2016-03-17 0:01 ` [PATCH v5 7/7][Update] cpufreq: schedutil: New governor based on scheduler utilization data Rafael J. Wysocki
2016-03-17 11:30 ` Juri Lelli
2016-03-17 12:54 ` Rafael J. Wysocki
2016-03-17 11:36 ` Peter Zijlstra
2016-03-17 12:54 ` Rafael J. Wysocki
2016-03-17 15:54 ` [PATCH v6 6/7][Update] cpufreq: Support for fast frequency switching Rafael J. Wysocki
2016-03-17 16:01 ` [PATCH v6 7/7][Update] cpufreq: schedutil: New governor based on scheduler utilization data Rafael J. Wysocki
2016-03-18 12:34 ` Patrick Bellasi
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