From: Tejun Heo <htejun@gmail.com>
To: David Rientjes <rientjes@google.com>
Cc: Mike Galbraith <efault@gmx.de>, Li Zefan <lizf@cn.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>,
Paul Menage <paul@paulmenage.org>
Subject: Re: [patch] cpusets: allow PF_THREAD_BOUND kworkers to escape from a cpuset
Date: Sat, 24 Sep 2011 12:21:47 +0900 [thread overview]
Message-ID: <20110924032147.GB29319@htj.dyndns.org> (raw)
In-Reply-To: <alpine.DEB.2.00.1109231304310.11347@chino.kir.corp.google.com>
Hello,
Sorry about the delay. I'm mostly offline until the end of this
month.
On Fri, Sep 23, 2011 at 01:20:51PM -0700, David Rientjes wrote:
> > @@ -1382,9 +1383,10 @@ static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont,
> > * set of allowed nodes is unnecessary. Thus, cpusets are not
> > * applicable for such threads. This prevents checking for success of
> > * set_cpus_allowed_ptr() on all attached tasks before cpus_allowed may
> > - * be changed.
> > + * be changed. We also disallow attaching kthreadd, to prevent it's
> > + * child from becoming trapped should it then acquire PF_THREAD_BOUND.
> > */
> > - if (tsk->flags & PF_THREAD_BOUND)
> > + if (tsk->flags & PF_THREAD_BOUND || tsk == kthreadd_task)
> > return -EINVAL;
> >
> > return 0;
>
> I like this much better, let's wait to hear from Tejun because he may
> shead some light on whether PF_THREAD_BOUND is really necessary for
> kworkers at all times.
Yes, PF_THREAD_BOUND is necessary. The whole thing depends heavily on
per-cpu behavior. In addition, I don't think it makes much sense to
put kworkers into a cpuset (or any other resource container) which
isn't global to the system. If certain CPU intensive tasks require
scheduler based resource limitation, the RTTD would be creating a
dedicated worker thread for it and put restrictions on that specific
kthread.
Putting kthreadd into a sub cpuset and thus putting restrictions on
random kthreads seems like asking for trouble. So, I agree with the
suggested approach.
Thank you.
--
tejun
next prev parent reply other threads:[~2011-09-24 3:21 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-23 6:21 Mike Galbraith
2011-09-23 7:00 ` Li Zefan
2011-09-23 7:19 ` Mike Galbraith
2011-09-23 9:12 ` David Rientjes
2011-09-23 9:42 ` Mike Galbraith
2011-09-23 10:53 ` Mike Galbraith
2011-09-23 13:27 ` David Rientjes
2011-09-23 14:33 ` Mike Galbraith
2011-09-23 18:16 ` Mike Galbraith
2011-09-23 20:20 ` David Rientjes
2011-09-24 3:21 ` Tejun Heo [this message]
2011-10-10 5:34 ` Mike Galbraith
2011-10-10 8:03 ` [patch] cpusets, cgroups: disallow attaching kthreadd Mike Galbraith
2011-10-10 16:43 ` Tejun Heo
2011-10-11 2:31 ` Mike Galbraith
2011-10-11 14:08 ` Peter Zijlstra
2011-10-11 16:57 ` Mike Galbraith
2011-10-12 1:22 ` David Rientjes
2011-10-12 1:45 ` Mike Galbraith
2011-10-12 1:20 ` David Rientjes
2011-10-18 8:10 ` patch] " Mike Galbraith
2011-10-18 8:16 ` David Rientjes
2011-10-18 8:42 ` Peter Zijlstra
2011-10-18 8:47 ` Mike Galbraith
2011-10-18 9:06 ` Peter Zijlstra
2011-10-18 9:23 ` Mike Galbraith
2011-10-18 10:11 ` Mike Galbraith
2011-10-18 20:38 ` David Rientjes
2011-10-19 4:00 ` Mike Galbraith
2011-10-19 4:53 ` Paul Menage
2011-10-19 4:56 ` Paul Menage
2011-10-19 5:28 ` Mike Galbraith
2011-10-19 7:50 ` Peter Zijlstra
2011-10-19 19:47 ` David Rientjes
2011-10-20 10:32 ` Peter Zijlstra
2011-10-20 21:24 ` David Rientjes
2011-10-19 4:57 ` Paul Menage
2011-10-19 5:24 ` [patch-final] " Mike Galbraith
2011-10-19 7:54 ` Peter Zijlstra
2011-10-19 8:00 ` Paul Menage
2011-10-19 8:21 ` Mike Galbraith
2011-10-26 20:27 ` David Rientjes
2011-11-10 20:51 ` David Rientjes
2011-12-06 20:13 ` David Rientjes
2011-12-06 22:47 ` Andrew Morton
2011-12-06 23:53 ` David Rientjes
2011-12-07 0:05 ` Andrew Morton
2011-12-07 3:18 ` [resubmit] " Mike Galbraith
2011-12-07 4:36 ` Mike Galbraith
2011-12-07 22:03 ` David Rientjes
2011-12-14 20:16 ` Andrew Morton
2011-12-15 2:50 ` David Rientjes
2012-01-06 22:06 ` Andrew Morton
2012-01-07 6:34 ` Mike Galbraith
2012-01-07 7:59 ` Andrew Morton
2011-12-07 22:01 ` David Rientjes
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