From: Ingo Molnar <mingo@elte.hu>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Schmidt <mschmidt@redhat.com>,
linux-kernel@vger.kernel.org,
"Eric W. Biederman" <ebiederm@xmission.com>,
Jon Masters <jcm@redhat.com>,
Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH] kthread: always create the kernel threads with normal priority
Date: Mon, 7 Jan 2008 12:09:04 +0100 [thread overview]
Message-ID: <20080107110904.GB28481@elte.hu> (raw)
In-Reply-To: <20080107022513.3ac05734.akpm@linux-foundation.org>
> > This causes a practical problem. When a runaway real-time task is
> > eating 100% CPU and we attempt to put the CPU offline, sometimes we
> > block while waiting for the creation of the highest-priority
> > "kstopmachine" thread.
sched-devel.git has new mechanisms against runaway RT tasks. There's a
new RLIMIT_RTTIME rlimit - if an RT task exceeds that rlimit then it is
sent SIGXCPU.
there's also a new group scheduling extension that is driven via a
sysctl:
/proc/sys/kernel/sched_rt_ratio
this way if a user has a runaway RT task, other users (and root) will
still have some CPU time left. (in Peter's latest patchset that is
replaced via rt_runtime_ns - but this is a detail)
so instead of the never-ending arms race of kernel thread priorities
against RT task priorities, we are going towards making RT tasks safer
on a policy level.
Ingo
next prev parent reply other threads:[~2008-01-07 11:09 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-17 22:43 [PATCH] kthread: run kthreadd with max priority SCHED_FIFO Michal Schmidt
2007-12-17 23:00 ` Jon Masters
2007-12-22 9:30 ` Andrew Morton
2007-12-22 9:52 ` Jon Masters
2007-12-22 10:11 ` Andrew Morton
2007-12-22 10:18 ` Jon Masters
2007-12-22 10:39 ` Mike Galbraith
2007-12-22 10:52 ` Andrew Morton
2007-12-22 11:21 ` Jon Masters
2007-12-23 8:50 ` Mike Galbraith
2008-01-07 10:06 ` [PATCH] kthread: always create the kernel threads with normal priority Michal Schmidt
2008-01-07 10:25 ` Andrew Morton
2008-01-07 11:09 ` Ingo Molnar [this message]
2008-01-07 17:29 ` Andrew Morton
2008-01-07 17:47 ` Peter Zijlstra
2008-01-08 9:54 ` Michal Schmidt
2008-01-07 13:18 ` Michal Schmidt
2008-01-08 16:22 ` Ingo Molnar
2008-01-07 11:22 ` Remy Bohmer
2008-01-07 13:10 ` Michal Schmidt
2008-01-07 15:53 ` Remy Bohmer
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