From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Paul Turner <pjt@google.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Clark Williams <clark@redhat.com>,
Andrew Theurer <habanero@us.ibm.com>
Subject: Re: [RFC] sched: The removal of idle_balance()
Date: Fri, 15 Feb 2013 13:32:59 +0100 [thread overview]
Message-ID: <1360931579.4736.29.camel@marge.simpson.net> (raw)
In-Reply-To: <1360930908.2739.1.camel@laptop>
On Fri, 2013-02-15 at 13:21 +0100, Peter Zijlstra wrote:
> On Fri, 2013-02-15 at 08:26 +0100, Mike Galbraith wrote:
> >
> > (the throttle is supposed to keep idle_balance() from doing severe
> > damage, that may want a peek/tweak)
>
> Right, as it stands idle_balance() can do a lot of work and if the avg
> idle time is less than the time we spend looking for a suitable task we
> loose.
>
> I've wanted to make this smarter by having the cpufreq/cpuidle avg idle
> time guestimator in the scheduler core so we actually know how log we
> expect to be idle and couple that with a cache refresh cost per sched
> domain (something we used to have pre 2.6.21 or so) so we can auto-limit
> the domain traversal for idle_balance.
>
> So far that's all fantasy though..
>
> Related, I wanted to use the idle time guestimate to 'optimize' the idle
> loop, currently that stuff is stupid expensive and pokes at timer
> hardware etc.. if we know we won't be idle longer than it takes to poke
> at timer hardware, don't go into nohz mode etc.
Yup. My trees have nohz throttled too, it's too expensive for fast
switchers scheduling cross core.
-Mike
next prev parent reply other threads:[~2013-02-15 12:33 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-15 6:13 [RFC] sched: The removal of idle_balance() Steven Rostedt
2013-02-15 7:26 ` Mike Galbraith
2013-02-15 12:07 ` Peter Zijlstra
2013-02-15 12:21 ` Peter Zijlstra
2013-02-15 12:32 ` Mike Galbraith [this message]
2013-02-16 16:12 ` Steven Rostedt
2013-02-17 6:26 ` Mike Galbraith
2013-02-17 7:14 ` Mike Galbraith
2013-02-17 21:54 ` Steven Rostedt
2013-02-18 3:42 ` Mike Galbraith
2013-02-18 15:23 ` Steven Rostedt
2013-02-18 17:22 ` Mike Galbraith
2013-02-15 7:45 ` Joonsoo Kim
2013-02-15 15:05 ` Steven Rostedt
2013-02-17 6:26 ` Mike Galbraith
2013-02-18 8:13 ` Srikar Dronamraju
2013-02-18 15:25 ` Steven Rostedt
2013-02-19 4:13 ` Rakib Mullick
2013-02-19 7:29 ` Michael Wang
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=1360931579.4736.29.camel@marge.simpson.net \
--to=efault@gmx.de \
--cc=acme@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=clark@redhat.com \
--cc=fweisbec@gmail.com \
--cc=habanero@us.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=pjt@google.com \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.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.