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

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Message-ID: <CAJZ5v0gVffRb33CJcrTY5KEPY04MQNp=uqsGFwMevZAEuYBGfg@mail.gmail.com>
Date:	Mon, 8 Feb 2016 13:52:28 +0100
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	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 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. :-)

Thanks,
Rafael