From: Daniel J Blueman <daniel@numascale-asia.com>
To: "Paul E. McKenney" <paul.mckenney@linaro.org>
Cc: Steffen Persvold <sp@numascale.com>, LKML <linux-kernel@vger.kernel.org>
Subject: False-positive RCU stall warnings on large systems...
Date: Wed, 20 Feb 2013 00:34:12 +0800 [thread overview]
Message-ID: <5123A984.4000704@numascale-asia.com> (raw)
Hi Paul,
On some of our larger servers with many hundreds of cores and when under
high duress, we can see scheduler RCU stall warnings [1], so find we
have to increase the hardcoded RCU_STALL_RAT_DELAY up from 2 and
RCU_JIFFIES_TILL_FORCE_QS up from 3.
Is there a more sustainable way to account for this to avoid it being
hard-coded, such as making it and dependent timeouts a fraction of
CONFIG_RCU_CPU_STALL_TIMEOUT?
On the other hand, perhaps this is just caused by clock jitter (eg due
to distance from a contended clock source)? So increasing these a bit
may just be adequate in general...
Many thanks,
Daniel
--- [1]
[ 3939.010085] INFO: rcu_sched detected stalls on CPUs/tasks: {}
(detected by 1, t=29662 jiffies, g=3053, c=3052, q=598)
[ 3939.020008] INFO: Stall ended before state dump start
--
Daniel J Blueman
Principal Software Engineer, Numascale Asia
next reply other threads:[~2013-02-19 16:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-19 16:34 Daniel J Blueman [this message]
2013-02-19 18:16 ` False-positive RCU stall warnings on large systems Paul E. McKenney
2013-02-20 3:35 ` Daniel J Blueman
2013-02-25 16:32 ` Paul E. McKenney
2013-03-05 9:02 ` Daniel J Blueman
2013-03-06 17:03 ` Paul E. McKenney
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