From: Mike Galbraith <bitbucket@online.de>
To: Lei Wen <leiwen@marvell.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
mingo@redhat.com, preeti.lkml@gmail.com,
daniel.lezcano@linaro.org, viresh.kumar@linaro.org,
xjian@marvell.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] sched: keep quiescent cpu out of idle balance loop
Date: Fri, 21 Feb 2014 06:51:43 +0100 [thread overview]
Message-ID: <1392961903.5451.58.camel@marge.simpson.net> (raw)
In-Reply-To: <1392949390-9867-1-git-send-email-leiwen@marvell.com>
On Fri, 2014-02-21 at 10:23 +0800, Lei Wen wrote:
> Cpu which is put into quiescent mode, would remove itself
> from kernel's sched_domain, and want others not disturb its
> task running. But current scheduler would not checking whether
> that cpu is setting in such mode, and still insist the quiescent
> cpu to response the nohz load balance.
Let's isolate some CPUs.
Setup:
/-----"system" CPU0
\
\---"rtcpus" CPUs1-3
crash> runqueues
PER-CPU DATA TYPE:
struct rq runqueues;
PER-CPU ADDRESSES:
[0]: ffff88022fc12c00
[1]: ffff88022fc92c00
[2]: ffff88022fd12c00
[3]: ffff88022fd92c00
crash> struct rq ffff88022fd92c00 | grep sd
sd = 0x0, <== yup, CPU3 is isolated bit of silicon
crash> struct rq ffff88022fd92c00 | grep rd
rd = 0xffffffff81bffe60 <def_root_domain>,
crash> struct -x root_domain 0xffffffff81bffe60
...
span = {{
bits = {0xe} <== "rtcpus"
}},
crash> struct rq ffff88022fc12c00 | grep rd
rd = 0xffff8802242c5800,
crash> struct -x root_domain 0xffff8802242c5800
...
span = {{
bits = {0x1} <== "system"
}},
Turn off load balancing in "system" as well now, CPU0 loses its 'sd',
and becomes an isolated island identical to "rtcpus" CPUs, and thus..
span = {{
bits = {0xf} <== oh darn
}},
.."system" and "rtcpus" merge, all CPUs having NULL sd, as they are now
all remote silicon islands, but they now also share rd again, as if you
had never diddled domains in the first place.
-Mike
next prev parent reply other threads:[~2014-02-21 5:51 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-19 5:20 [PATCH] sched: keep quiescent cpu out of idle balance loop Lei Wen
2014-02-19 9:04 ` Peter Zijlstra
2014-02-20 2:42 ` Lei Wen
2014-02-20 8:50 ` Peter Zijlstra
2014-02-20 9:15 ` Lei Wen
2014-02-20 9:17 ` Lei Wen
2014-02-20 12:04 ` Peter Zijlstra
2014-02-20 12:23 ` Peter Zijlstra
2014-02-21 2:23 ` [PATCH v2] " Lei Wen
2014-02-21 5:51 ` Mike Galbraith [this message]
2014-02-21 7:28 ` Lei Wen
2014-02-21 8:34 ` Mike Galbraith
2014-02-21 9:15 ` [PATCH v3] " Lei Wen
2014-02-21 9:41 ` Mike Galbraith
2014-02-21 9:15 ` [PATCH v2] " 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=1392961903.5451.58.camel@marge.simpson.net \
--to=bitbucket@online.de \
--cc=daniel.lezcano@linaro.org \
--cc=leiwen@marvell.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=preeti.lkml@gmail.com \
--cc=viresh.kumar@linaro.org \
--cc=xjian@marvell.com \
/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