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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAKfTPtC0x+ZOUZxEYahXwXGXSd5eATUhTDtRc=9sko8V896YQw@mail.gmail.com>
Date:	Thu, 10 Mar 2016 09:12:12 +0700
From:	Vincent Guittot <vincent.guittot@...aro.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Juri Lelli <juri.lelli@....com>,
	Steve Muckle <steve.muckle@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering
 utilization update callbacks

On 9 March 2016 at 19:35, Peter Zijlstra <peterz@...radead.org> wrote:
> On Mon, Feb 15, 2016 at 10:47:22PM +0100, Rafael J. Wysocki wrote:
>> From: Rafael J. Wysocki <rafael.j.wysocki@...el.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@...el.com>
>> Acked-by: Viresh Kumar <viresh.kumar@...aro.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@...radead.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

> --
> To unsubscribe from this list: send the line "unsubscribe linux-pm" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html