From: Pavel Machek <pavel@ucw.cz>
To: Ingo Molnar <mingo@elte.hu>
Cc: kernel list <linux-kernel@vger.kernel.org>, tglx@linutronix.de
Subject: Re: nohz and strange sleep latencies
Date: Mon, 19 Nov 2007 22:11:42 +0100 [thread overview]
Message-ID: <20071119211142.GA1857@elf.ucw.cz> (raw)
In-Reply-To: <20071119205555.GA28696@elte.hu>
Hi!
> > On unloaded x60 system, 2.6.24-rc3 (tainted-pavel-so if someone can
> > reproduce it, it would be helpful):
> >
> > pavel@amd:~$ while true; do time sleep 0.01; done
> > 0.00user 0.00system 0.01 (0m0.013s) elapsed 30.71%CPU
> > 0.00user 0.00system 0.02 (0m0.024s) elapsed 8.36%CPU
> > 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.53%CPU
> > 0.00user 0.00system 0.02 (0m0.026s) elapsed 7.75%CPU
> > 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.34%CPU
> > 0.00user 0.00system 0.20 (0m0.207s) elapsed 1.45%CPU
> > 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.59%CPU
> > 0.00user 0.00system 0.23 (0m0.230s) elapsed 1.30%CPU
> > 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.61%CPU
> > 0.00user 0.00system 0.20 (0m0.201s) elapsed 1.48%CPU
> > 0.00user 0.00system 0.01 (0m0.013s) elapsed 15.50%CPU
> > 0.00user 0.00system 0.19 (0m0.190s) elapsed 1.05%CPU
> > 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.37%CPU
> > 0.00user 0.00system 0.04 (0m0.049s) elapsed 4.09%CPU
> > 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.35%CPU
> > 0.00user 0.00system 0.01 (0m0.017s) elapsed 11.89%CPU
> > 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.38%CPU
> > 0.00user 0.00system 0.08 (0m0.081s) elapsed 3.71%CPU
> > 0.00user 0.00system 0.01 (0m0.013s) elapsed 23.33%CPU
> > 0.00user 0.00system 0.01 (0m0.019s) elapsed 15.92%CPU
> >
> > nohz=off helps a lot. while true; do time sleep 0.0; done does not
> > have unexpected latencies.
>
> does hpet=disable on the boot line also help? (without nohz=off)
hpet-disable helps.. a bit. 200msec latencies are gone. (What is used
for wakeups in this case?)
pavel@amd:~$ while true; do time sleep 0.01; done
0.00user 0.00system 0.01 (0m0.013s) elapsed 22.96%CPU
0.00user 0.00system 0.01 (0m0.018s) elapsed 11.05%CPU
0.00user 0.00system 0.01 (0m0.013s) elapsed 15.54%CPU
0.00user 0.00system 0.03 (0m0.037s) elapsed 8.05%CPU
0.00user 0.00system 0.01 (0m0.013s) elapsed 23.34%CPU
0.00user 0.00system 0.03 (0m0.037s) elapsed 8.14%CPU
0.00user 0.00system 0.01 (0m0.013s) elapsed 23.33%CPU
0.00user 0.00system 0.03 (0m0.037s) elapsed 8.16%CPU
0.00user 0.00system 0.01 (0m0.013s) elapsed 23.30%CPU
0.00user 0.00system 0.03 (0m0.037s) elapsed 5.47%CPU
0.00user 0.00system 0.01 (0m0.013s) elapsed 23.25%CPU
0.00user 0.00system 0.01 (0m0.013s) elapsed 15.54%CPU
0.00user 0.00system 0.01 (0m0.013s) elapsed 15.56%CPU
0.00user 0.00system 0.03 (0m0.036s) elapsed 5.49%CPU
0.00user 0.00system 0.01 (0m0.013s) elapsed 23.35%CPU
0.00user 0.00system 0.03 (0m0.037s) elapsed 8.14%CPU
0.00user 0.00system 0.01 (0m0.013s) elapsed 23.35%CPU
0.00user 0.00system 0.03 (0m0.037s) elapsed 8.14%CPU
0.00user 0.00system 0.01 (0m0.013s) elapsed 23.34%CPU
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2007-11-19 21:11 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-19 20:31 nohz and strange sleep latencies Pavel Machek
2007-11-19 20:55 ` Ingo Molnar
2007-11-19 21:11 ` Pavel Machek [this message]
2007-11-20 8:57 ` Ingo Molnar
2007-11-20 9:05 ` Ingo Molnar
2007-11-20 10:54 ` Pavel Machek
2007-11-20 20:54 ` Ingo Molnar
2007-11-20 22:48 ` Thomas Gleixner
2007-11-20 22:52 ` Ingo Molnar
2007-11-22 10:09 ` Pavel Machek
2007-11-22 18:51 ` Pavel Machek
2007-11-22 18:52 ` Pavel Machek
2007-11-22 20:29 ` Thomas Gleixner
2007-11-23 12:22 ` Pavel Machek
2007-11-24 22:29 ` Pavel Machek
2007-11-24 22:40 ` Pavel Machek
2007-11-24 23:29 ` Rafael J. Wysocki
2007-11-24 23:35 ` Rafael J. Wysocki
2007-11-25 21:51 ` Thomas Gleixner
2007-11-25 20:25 ` [patch] " Pavel Machek
2007-11-25 21:42 ` Thomas Gleixner
2007-11-26 11:54 ` Pavel Machek
2007-11-20 9:44 ` Thomas Gleixner
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=20071119211142.GA1857@elf.ucw.cz \
--to=pavel@ucw.cz \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=tglx@linutronix.de \
/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