From: Oleg Nesterov <oleg@tv-sign.ru>
To: Mark Hounschell <dmarkh@cfl.rr.com>
Cc: Mark Hounschell <markh@compro.net>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: floppy.c soft lockup
Date: Sun, 3 Jun 2007 12:14:17 +0400 [thread overview]
Message-ID: <20070603081417.GA81@tv-sign.ru> (raw)
In-Reply-To: <4661D698.5040009@cfl.rr.com>
On 06/02, Mark Hounschell wrote:
>
> Jun 2 16:36:11 harley kernel: ERR!! events/1 flush hang: c201dbc0
> c201dbc0 10012 10012
> Jun 2 16:36:11 harley kernel: CURR: 7974 7974 vrsx 93 26
> Jun 2 16:36:11 harley kernel: wq_barrier_func+0x0/0x8
> Jun 2 16:36:11 harley kernel: vmstat_update+0x0/0x24
> Jun 2 16:36:11 harley kernel: ----
> Jun 2 16:36:11 harley kernel: cache_reap+0x0/0xf4
As expected.
Note that ->nivcsw/->nvcsw doesn't change. There is no "spare time"
on CPU 1, "vrsx" monopolizes CPU. events/1->cache_reap() was preempted
by vrsx, it had no chance to run since then. Note that jobs == 7974
doesn't change too. I forgot to print cwq->thread->state, but it should
be TASK_RUNNING. It would not be possible to kill vrsx if cache_reap()
stalled.
I don't think this is a kernel problem, vrsx breaks flush_workqueue().
Ingo can answer authoritatively, but I think SCHED_RR/SCHED_FIFO were
not designed to be 100% cpu-bound.
That said, I think it makes sense to get rid of flush_scheduled_work()
in floppy.c.
Thanks!
Oleg.
next prev parent reply other threads:[~2007-06-03 8:14 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-29 17:31 floppy.c soft lockup Mark Hounschell
2007-05-31 5:46 ` Andrew Morton
2007-05-31 14:28 ` Mark Hounschell
2007-05-31 17:06 ` Oleg Nesterov
2007-05-31 18:01 ` Mark Hounschell
2007-05-31 18:44 ` Mark Hounschell
2007-05-31 19:22 ` Oleg Nesterov
2007-05-31 20:18 ` Mark Hounschell
2007-06-01 9:51 ` Mark Hounschell
2007-06-01 11:00 ` Oleg Nesterov
2007-06-01 14:10 ` Mark Hounschell
2007-06-01 15:16 ` Oleg Nesterov
2007-06-01 17:11 ` Mark Hounschell
2007-06-01 18:36 ` Oleg Nesterov
2007-06-01 19:52 ` Mark Hounschell
2007-06-02 12:30 ` Oleg Nesterov
2007-06-02 20:44 ` Mark Hounschell
2007-06-03 8:14 ` Oleg Nesterov [this message]
2007-06-04 14:00 ` Mark Hounschell
2007-06-06 13:12 ` Mark Hounschell
2007-06-06 17:28 ` Andrew Morton
2007-06-07 1:31 ` Matt Mackall
2007-06-07 10:18 ` Mark Hounschell
2007-06-07 14:25 ` Matt Mackall
2007-06-08 9:54 ` Mark Hounschell
2007-06-13 16:17 ` Oleg Nesterov
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