From: Mike Galbraith <efault@gmx.de>
To: "Артем Анисимов" <aanisimov@inbox.ru>
Cc: linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, mingo@elte.hu
Subject: Re: Commit 1e5a74059f9 broke utime measurement of ptraced() processes
Date: Sat, 24 Dec 2011 08:42:46 +0100 [thread overview]
Message-ID: <1324712566.5025.12.camel@marge.simson.net> (raw)
In-Reply-To: <201112241026.35726.aanisimov@inbox.ru>
On Sat, 2011-12-24 at 10:26 +0300, Артем Анисимов wrote:
> I believe that the described behaviour is erroneous and in order to
> > lessen the odds of it [waker] being preempted again soon
> one should not mess with utime but rather use another technique. It is also
> interesting why the *user time* needs to be affected? It is inside the kernel
> that the tracer process is woken up, so when
> > handing a few wakeup expense cycles to the wakee
> why not account those cycles as stime?
CPU utilization shifts with wakeup preemption, so there will be visible
effect when you change wakeup preemption in any way.
> Also I'd like to know if there is a way to get reliable utime measurements
> in recent kernels.
If wakeup preemption is undesirable, you could run SCHED_BATCH.
-Mike
next prev parent reply other threads:[~2011-12-24 7:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-19 12:19 Артем Анисимов
2011-12-20 13:39 ` Mike Galbraith
2011-12-24 7:26 ` Артем Анисимов
2011-12-24 7:42 ` Mike Galbraith [this message]
2011-12-27 8:30 ` Артем Анисимов
2011-12-27 8:04 ` Mike Galbraith
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=1324712566.5025.12.camel@marge.simson.net \
--to=efault@gmx.de \
--cc=a.p.zijlstra@chello.nl \
--cc=aanisimov@inbox.ru \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®