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From: Thomas Gleixner <tglx@linutronix.de>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>,
	sedat.dilek@gmail.com, Paul McKenney <paul.mckenney@linaro.org>,
	LKML <linux-kernel@vger.kernel.org>,
	x86@kernel.org, linux-next <linux-next@vger.kernel.org>
Subject: Re: [next-20120823] NOHZ: local_softirq_pending 200 on s/r
Date: Fri, 24 Aug 2012 17:40:06 +0200 (CEST)	[thread overview]
Message-ID: <alpine.LFD.2.02.1208241738130.2856@ionos> (raw)
In-Reply-To: <20120824145247.GB2472@linux.vnet.ibm.com>

On Fri, 24 Aug 2012, Paul E. McKenney wrote:

> On Fri, Aug 24, 2012 at 09:26:08AM +0200, Mike Galbraith wrote:
> > On Thu, 2012-08-23 at 12:04 +0200, Sedat Dilek wrote:
> > 
> > > Jack Winter confirmed to see similiar NOHZ messages also on
> > > v3.4.9-rt17 kernel (CPU: Core2Duo when no suspend performed):
> > > 
> > > [15223.171585] NOHZ: local_softirq_pending 08
> > 
> > These can be caused by blocking while holding local_softirq_lock.

> > Even with per softirq threads, and then (yet more overhead) splitting
> > the lock to make sure one softirq type can't block another, _and_ only
> > griping if the lock for the pending softirq is _not_ held, seems the
> > little bugger can still be triggered very rarely by syn flood induced
> > handler bail/raise.  Annoying little gripe :)
> 
> Hmmm...  Now that you mention it, if I understand correctly, the
> conversion of spinlocks to sleeplocks in -rt would seem to invalidate
> this particular diagnostic completely.
> 
> So, what am I missing?

I wonder whether the softirq_check_pending_idle() check needs a few
tweaks for RT, but I have to see a proper context for the failure
scenario first.

Thanks,

	tglx

      reply	other threads:[~2012-08-24 15:40 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-23 10:04 [next-20120823] NOHZ: local_softirq_pending 200 on s/r Sedat Dilek
2012-08-23 10:46 ` Thomas Gleixner
2012-08-23 15:43   ` Paul E. McKenney
2012-08-23 16:06     ` Sedat Dilek
2012-08-23 17:14       ` Paul E. McKenney
2012-08-23 18:55         ` Sedat Dilek
2012-08-23 19:09           ` Paul E. McKenney
2012-08-24  7:26 ` Mike Galbraith
2012-08-24 14:52   ` Paul E. McKenney
2012-08-24 15:40     ` Thomas Gleixner [this message]

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