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RE: regression caused by bb6ab52f2bef ("intel_pstate: Do not set utilization update hook too early")

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Dear all,

If using acpi-cpufreq instead, v4.6, v4.6-rc3, v4.7-rc3 can't reproduce the issue. It seems
only intel_pstate is impacted.

Thanks,
Jisheng
________________________________________
From: Jisheng Zhang
Sent: Friday, June 17, 2016 23:53
To: Rafael J. Wysocki
Cc: Peter Zijlstra; Paul E. McKenney; Rafael J. Wysocki; Viresh Kumar; linux-pm@vger.kernel.org; Linux Kernel Mailing List
Subject: RE: regression caused by bb6ab52f2bef ("intel_pstate: Do not set utilization update hook too early")

Dear Rafael,

I used intel_pstate.

I just tested v4.7-rc3, which should include commit 4578ee7e1def intel_pstate: Avoid
unnecessary synchronize_sched() during initialization, I can still get the same
wakeups, so it's not sufficient.

Another clue maybe helpful, I found these top2 wakeup/s is consistent, e.g
rcu_sched always gives about 10 wakeups/s, and tick_sched_timer gave
5.6-5.9 wakeups/s,

            144.3 µs/s      10.0        Process        [rcu_sched]

            193.9 µs/s       5.7        Timer          tick_sched_timer

Thanks,
Jisheng

________________________________________
From:  Rafael J. Wysocki
Sent: Friday, June 17, 2016 23:42
To: Jisheng Zhang
Cc: Peter Zijlstra; Paul E. McKenney; Rafael J. Wysocki; Viresh Kumar; linux-pm@vger.kernel.org; Linux Kernel Mailing List
Subject: Re: regression caused by bb6ab52f2bef ("intel_pstate: Do not set utilization update hook too early")

On Fri, Jun 17, 2016 at 5:40 PM, Rafael J. Wysocki  wrote:
> On Fri, Jun 17, 2016 at 5:32 PM, Jisheng Zhang  wrote:
>> Hi all,
>>
>> First of all, sorry for top post, only webmail is available now.
>>
>> Second, sorry again for report incorrect commit, I were too tired this morning so I remember the wrong commit.  The regression is caused by bb6ab52f2bef ("intel_pstate: Do not set utilization update hook too early"), so I update the email title.
>
> OK, that makes much more sense. :-)
>
> And
>
> 4578ee7e1def intel_pstate: Avoid unnecessary synchronize_sched()
> during initialization
>
> is not sufficient I suppose?

I mean, it is not sufficient to reduce the number of wakeups again?

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regression caused by 08f511fd41c3 ("cpufreq: Reduce  cpufreq_update_util() overhead a bit") Jisheng Zhang <jszhang@marvell.com> - 2016-06-17 10:40 +0200
  Re: regression caused by 08f511fd41c3 ("cpufreq: Reduce  cpufreq_update_util() overhead a bit") Jisheng Zhang <jszhang@marvell.com> - 2016-06-17 10:50 +0200
    Re: regression caused by 08f511fd41c3 ("cpufreq: Reduce  cpufreq_update_util() overhead a bit") "Rafael J. Wysocki" <rafael@kernel.org> - 2016-06-17 15:10 +0200
      Re: regression caused by 08f511fd41c3 ("cpufreq: Reduce  cpufreq_update_util() overhead a bit") "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-17 15:20 +0200
        Re: regression caused by 08f511fd41c3 ("cpufreq: Reduce  cpufreq_update_util() overhead a bit") Peter Zijlstra <peterz@infradead.org> - 2016-06-17 16:10 +0200
          Re: regression caused by 08f511fd41c3 ("cpufreq: Reduce  cpufreq_update_util() overhead a bit") "Rafael J. Wysocki" <rafael@kernel.org> - 2016-06-17 17:40 +0200
          RE: regression caused by bb6ab52f2bef ("intel_pstate: Do not set  utilization update hook too early") Jisheng Zhang <jszhang@marvell.com> - 2016-06-17 17:40 +0200
            Re: regression caused by bb6ab52f2bef ("intel_pstate: Do not set  utilization update hook too early") "Rafael J. Wysocki" <rafael@kernel.org> - 2016-06-17 17:50 +0200
              Re: regression caused by bb6ab52f2bef ("intel_pstate: Do not set  utilization update hook too early") "Rafael J. Wysocki" <rafael@kernel.org> - 2016-06-17 17:50 +0200
                RE: regression caused by bb6ab52f2bef ("intel_pstate: Do not set  utilization update hook too early") Jisheng Zhang <jszhang@marvell.com> - 2016-06-17 18:00 +0200
                RE: regression caused by bb6ab52f2bef ("intel_pstate: Do not set  utilization update hook too early") Jisheng Zhang <jszhang@marvell.com> - 2016-06-17 18:20 +0200
            RE: regression caused by bb6ab52f2bef ("intel_pstate: Do not set utilization update hook too early") "Doug Smythies" <dsmythies@telus.net> - 2016-06-23 18:20 +0200

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