From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Don Zickus <dzickus@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
Mandeep Singh Baines <msb@chromium.org>
Subject: Re: [PATCH] watchdog: Make sure the watchdog thread gets CPU on loaded system
Date: Thu, 15 Mar 2012 17:04:31 +0100 [thread overview]
Message-ID: <1331827471.18960.195.camel@twins> (raw)
In-Reply-To: <20120315155413.GE3941@redhat.com>
On Thu, 2012-03-15 at 11:54 -0400, Don Zickus wrote:
> > > Why did watchdog() reset the scheduling policy seven instructions
> > > before exiting? Seems pointless.
> >
> > It has been introduced by Thomas in cba9bd22. To be honest I don't
> > understand why it makes a sense?
>
> Yeah I noticed that too. I didn't bother questioning it either when
> it
> went in. I just assumed Thomas and Peter know scheduling a lot better
> than I do. :-)
I just dug through my IRC logs and the reason is that running the entire
exit path as a highest priority RT task incurs a latency spike to other
tasks running on the system (313us). Since there's absolutely no point
in running the exit path as a RT task, tglx made it not do that.
next prev parent reply other threads:[~2012-03-15 16:04 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-14 20:38 Don Zickus
2012-03-14 20:59 ` Mandeep Singh Baines
2012-03-14 23:19 ` Andrew Morton
2012-03-15 1:45 ` Mandeep Singh Baines
2012-03-15 11:00 ` Peter Zijlstra
2012-03-15 11:06 ` Peter Zijlstra
2012-03-15 12:42 ` Ingo Molnar
2012-03-15 14:00 ` Peter Zijlstra
2012-03-15 14:35 ` Don Zickus
2012-03-15 15:39 ` Mandeep Singh Baines
2012-03-15 16:10 ` Peter Zijlstra
2012-03-15 16:11 ` Peter Zijlstra
2012-03-15 16:16 ` Peter Zijlstra
2012-03-15 17:04 ` Mandeep Singh Baines
2012-03-15 8:02 ` Michal Hocko
2012-03-15 15:54 ` Don Zickus
2012-03-15 16:04 ` Peter Zijlstra [this message]
2012-03-19 22:00 ` Andrew Morton
2012-03-15 16:14 ` Michal Hocko
2012-03-15 17:14 ` Don Zickus
-- strict thread matches above, loose matches on Subject: below --
2012-03-13 9:45 [PATCH] watchdog: make " Michal Hocko
2012-03-13 13:42 ` Don Zickus
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=1331827471.18960.195.camel@twins \
--to=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=dzickus@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mhocko@suse.cz \
--cc=mingo@elte.hu \
--cc=msb@chromium.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 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®