From: Igor Zhbanov <i.zhbanov at samsung.com>
To: powertop@lists.01.org
Subject: Re: [Powertop] Powertop doesn't detects sleeping ARM cores
Date: Thu, 20 Sep 2012 13:57:10 +0400 [thread overview]
Message-ID: <505AE876.4080105@samsung.com> (raw)
In-Reply-To: 20120920094354.GB3237@swordfish.minsk.epam.com
[-- Attachment #1: Type: text/plain, Size: 1999 bytes --]
Sergey Senozhatsky wrote:
> On (09/20/12 13:29), Igor Zhbanov wrote:
>>> On (09/20/12 12:24), Igor Zhbanov wrote:
>>>> Chris Ferron wrote:
>>>>
>>>> Now I'm looking for solution. But I see now only four ways:
>>>>
>>>> 1) Develop another kernel mechanism for providing information about all available
>>>> CPUs and cores. Or ask the kernel authors not to remove offline cores from
>>>> /proc/cpuinfo and their information files from /sys/.../cpu/.
>>> procps (e.g. top utility) use sysconf _SC_NPROCESSORS_CONF/_SC_NPROCESSORS_ONLN for
>>> that purpose.
>>>
>>> https://www.gnu.org/software/libc/manual/html_node/Processor-Resources.html
>> Counting of the CPUs is the least problem. (By the way, how sysconf() figures
>> out the number? I suppose that it reads /proc/cpuinfo of scans /sys/.
>> Is there any other way?).
>>
>> The problem is that the PowerTOP needs to read information about cores
>> from the files in /sys/.../cpu/cpuX/ directory (about C- and P-states, siblings
>> etc). And needed files in these directories are present only for cores
>> which are currently online.
> right, I was thinking about that some time ago: and from the top of my head kind of a solution
> seemed to be to track number of CPUs before measure, compare with the previously known one,
> and "re-init" powertop (at least rebuild CPUs part), but it's not that often that I offline/online
> CPUs, so I decided to drop it. with ARM we have a different story.
>
> on x86(_64) "dirty" CPU offline support looks "easy", just make get_msr() error non-fatal.
> online -- that's the problem, agree.
Perhaps PowerTOP could wake up every core in its calibration phase and story collected
information in platform config file.
--
Best regards,
Igor Zhbanov,
Expert Software Engineer,
phone: +7 (495) 797 25 00 ext 3806
e-mail: i.zhbanov(a)samsung.com
ASWG, Moscow R&D center, Samsung Electronics
12 Dvintsev street, building 1
127018, Moscow, Russian Federation
next reply other threads:[~2012-09-20 9:57 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-20 9:57 Igor Zhbanov [this message]
-- strict thread matches above, loose matches on Subject: below --
2012-09-20 10:55 [Powertop] Powertop doesn't detects sleeping ARM cores Igor Zhbanov
2012-09-20 10:42 Arjan van de Ven
2012-09-20 10:40 Igor Zhbanov
2012-09-20 9:56 Arjan van de Ven
2012-09-20 9:43 Sergey Senozhatsky
2012-09-20 9:29 Igor Zhbanov
2012-09-20 9:14 Sergey Senozhatsky
2012-09-20 8:24 Igor Zhbanov
2012-09-19 15:15 Chris Ferron
2012-09-19 8:26 Igor Zhbanov
2012-09-17 12:57 Igor Zhbanov
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