Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering utilization update callbacks

From	Vincent Guittot <vincent.guittot@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering utilization update callbacks
Date	2016-03-10 03:20 +0100
Message-ID	<raYmK-aJ-29@gated-at.bofh.it> (permalink)
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On 9 March 2016 at 19:35, Peter Zijlstra <peterz@infradead.org> wrote:
> On Mon, Feb 15, 2016 at 10:47:22PM +0100, Rafael J. Wysocki wrote:
>> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>>
>> Introduce a mechanism by which parts of the cpufreq subsystem
>> ("setpolicy" drivers or the core) can register callbacks to be
>> executed from cpufreq_update_util() which is invoked by the
>> scheduler's update_load_avg() on CPU utilization changes.
>>
>> This allows the "setpolicy" drivers to dispense with their timers
>> and do all of the computations they need and frequency/voltage
>> adjustments in the update_load_avg() code path, among other things.
>>
>> The update_load_avg() changes were suggested by Peter Zijlstra.
>>
>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
>> ---
>>  drivers/cpufreq/cpufreq.c |   45 +++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/cpufreq.h   |   34 ++++++++++++++++++++++++++++++++++
>>  kernel/sched/deadline.c   |    4 ++++
>>  kernel/sched/fair.c       |   26 +++++++++++++++++++++++++-
>>  kernel/sched/rt.c         |    4 ++++
>>  kernel/sched/sched.h      |    1 +
>>  6 files changed, 113 insertions(+), 1 deletion(-)
>>
>
> So with the understanding that we'll work on getting rid of
> cpufreq_trigger_update().
>
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
>
> Also, Vincent had some concerns about the exact placement of the
> callback, and I see no problem in moving it if there's need.

Yes, as explained previously we can probably  use other placement to
not miss any immediate change of rq's utilization because of task
migration but this optimization can probably be done in a next step

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Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering  utilization update callbacks Peter Zijlstra <peterz@infradead.org> - 2016-03-09 13:40 +0100
  Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering  utilization update callbacks "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-09 14:30 +0100
  Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering  utilization update callbacks "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-09 14:40 +0100
  Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering  utilization update callbacks Ingo Molnar <mingo@kernel.org> - 2016-03-09 14:40 +0100
  Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering  utilization update callbacks Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-10 03:20 +0100

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