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 13:29:40 +0400 [thread overview]
Message-ID: <505AE204.6090907@samsung.com> (raw)
In-Reply-To: 20120920091433.GA3237@swordfish.minsk.epam.com
[-- Attachment #1: Type: text/plain, Size: 1392 bytes --]
Sergey Senozhatsky 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.
So the Powertop is unable
1) To count the number of available CPUs.
2) To read information about all CPUs.
--
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 9:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-20 9:29 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 9:57 Igor Zhbanov
2012-09-20 9:56 Arjan van de Ven
2012-09-20 9:43 Sergey Senozhatsky
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=505AE204.6090907@samsung.com \
--to=powertop@lists.01.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.