linux-kernel - Re: [PATCH] cpufreq: intel_pstate: Change the calculation of next pstate

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: <535FD4A6.3050905@semaphore.gr>
Date:	Tue, 29 Apr 2014 19:34:46 +0300
From:	Stratos Karafotis <stratosk@...aphore.gr>
To:	Viresh Kumar <viresh.kumar@...aro.org>,
	Dirk Brandewie <dirk.j.brandewie@...el.com>
CC:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: intel_pstate: Change the calculation of next
 pstate

On 29/04/2014 07:58 πμ, Viresh Kumar wrote:
> Cc'd Dirk,
> 
> On 28 April 2014 03:42, Stratos Karafotis <stratosk@...aphore.gr> wrote:
>> Currently the driver calculates the next pstate proportional to
>> core_busy factor and reverse proportional to current pstate.
>>
>> Change the above method and calculate the next pstate independently
>> of current pstate.
> 
> We must mention why the change is required.
> 

Hi Viresh,

Actually, I can't say that it's required. :)
I just believe that calculation of next p-state should be independent
from current one. In my opinion we can't scale the load across different
p-states, because it's not always equivalent.

For example suppose a load of 100% because of a tight for loop in the
current p-state. It will be also a 100% load in any other p-state.
It will be wrong if we scale the load in the calculation formula
according to the current p-state.

I included the test results in the change log to point out an improvement
because of this patch.

I will enrich more the change log as you suggested.

Thanks,
Stratos Karafotis

--
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/