linux-kernel - Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization update callbacks

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Message-ID: <CAJZ5v0hGHUSUnQmr+uQHjS-4xHL8PFXmMDJ-e2ShxPxH0hPFAA@mail.gmail.com>
Date:	Mon, 8 Feb 2016 14:40:39 +0100
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Juri Lelli <juri.lelli@....com>,
	Steve Muckle <steve.muckle@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization
 update callbacks

On Mon, Feb 8, 2016 at 1:52 PM, Rafael J. Wysocki <rafael@...nel.org> wrote:
> On Mon, Feb 8, 2016 at 12:52 PM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
>> On 08-02-16, 03:08, Rafael J. Wysocki wrote:
>>> Moreover, update_sampling_rate() doesn't need to walk the cpu_dbs_infos,
>>> it may walk policies instead.  Like after the (untested) appended patch.
>>>
>>> Then, if we have a governor_data_lock in struct policy, we can use that
>>> to protect policy_dbs while it is being access there and we're done.
>>>
>>> I'll try to prototype something along these lines tomorrow.
>>
>> I have solved that in a different way, and dropped the lock from
>> update_sampling_rate(). Please see if that looks good.
>
> Well, almost.
>
> I like the list approach, but you need to be careful about it.  Let me
> comment more on the patches in the series.
>
> I have a gut feeling that my idea of walking policies will end up
> being simpler in the end, but let's see. :-)

Well, my gut feeling seems to have been incorrect, as often happens.

Thanks,
Rafael