linux-kernel - Re: [PATCH v2] cpufreq: Don't destroy/realloc policy/sysfs on hotplug/suspend

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Message-ID: <53C62E93.8010307@mit.edu>
Date:	Wed, 16 Jul 2014 13:19:39 +0530
From:	"Srivatsa S. Bhat" <srivatsa@....EDU>
To:	Viresh Kumar <viresh.kumar@...aro.org>
CC:	Saravana Kannan <skannan@...eaurora.org>,
	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	Todd Poynor <toddpoynor@...gle.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Stephen Boyd <sboyd@...eaurora.org>
Subject: Re: [PATCH v2] cpufreq: Don't destroy/realloc policy/sysfs on hotplug/suspend

On 07/16/2014 11:14 AM, Viresh Kumar wrote:
> On 15 July 2014 12:28, Srivatsa S. Bhat <srivatsa@....edu> wrote:
>> Wait, allowing an offline CPU to be the policy->cpu (i.e., the CPU which is
>> considered as the master of the policy/group) is just absurd.
> 
> Yeah, that was as Absurd as I am :)
> 

I have had my own share of silly ideas over the years; so don't worry, we are
all in the same boat ;-)

>> The goal of this patchset should be to just de-couple the sysfs files/ownership
>> from the policy->cpu to an extent where it doesn't matter who owns those
>> files, and probably make it easier to do CPU hotplug without having to
>> destroy and recreate the files on every hotplug operation.
> 
> I went to that Absurd idea because we thought we can skip playing with
> the sysfs nodes on suspend/hotplug.
> 
> And if policy->cpu keeps changing with hotplug, we *may* have to keep
> sysfs stuff moving as well. One way to avoid that is by using something
> like: policy->sysfs_cpu, but wasn't sure if that's the right path to follow.
>

Hmm, I understand.. Even I don't have any suggestions as of now, since I
haven't spent enough time thinking of alternatives yet.

> Lets see what Saravana's new patchset has for us :)
> 

Yep :-)

Regards,
Srivatsa S. Bhat
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