linux-kernel - Re: [PATCH v3 1/3] cpufreq: Add boost frequency support in core

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

Message-ID: <CAKohpo=Th-V4+i7r0+EoDL2fvoy-vMZrRa7wg5mJSQ7HjK_0YQ@mail.gmail.com>
Date:	Tue, 18 Jun 2013 14:10:28 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Lukasz Majewski <l.majewski@...sung.com>
Cc:	"Rafael J. Wysocky" <rjw@...k.pl>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Jonghwa Lee <jonghwa3.lee@...sung.com>,
	Myungjoo Ham <myungjoo.ham@...sung.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Lukasz Majewski <l.majewski@...ess.pl>,
	Andre Przywara <andre.przywara@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Amit Daniel Kachhap <amit.daniel@...sung.com>
Subject: Re: [PATCH v3 1/3] cpufreq: Add boost frequency support in core

On 18 June 2013 13:54, Lukasz Majewski <l.majewski@...sung.com> wrote:
> On Tue, 18 Jun 2013 08:42:13 +0200, Viresh Kumar wrote:

>> Its not about how long.. One cpu type can work longer with boost freq
>> compared to other.
>>
>> What we probably need is:
>> - Enabled boost from sysfs if required (now below steps will come into
>>   picture)
>> - See how many cpus are running, if only one then start using boost
>> freqs
>
> You are right here.
>
> I'd like to propose following solution:
> 1. For acpi (where boost_enable come into play) - do not consider
> number of active cpus (this is done in HW anyway)
>
> 2. For SW solution evaluate how many CPUs are running. If only one is
> running then allow enabling boost from sysfs.

Looks fine.

> But following situation is also possible: User enable boost when one
> core is only running and then for some reason other core is woken up.
> What shall be done then?
> Shall we then disable boost immediately when cpufreq detects that
> more than one core is running? Or leave this situation to be handled by
> thermal subsystem?

Obviously disable boost ASAP. Every SoC might not have a thermal
framework glue to do it.

> As a side note:
> Logic proposed at point 2, is already implemented at LAB
> (enable LAB only when one core is running and disable it when more
> than one come into play).

Hmm.. So, eventually that will go away now :)

>> - Now thermal should be come into picture to save chip in case a
>> single cpu running at boost can burn it out.
>
> I will extent v4 to embrace code which switches off boost at thermal.

Gud.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/