Re: [next-20120823] NOHZ: local_softirq_pending 200 on s/r

From: Mike Galbraith
Date: Fri Aug 24 2012 - 03:26:45 EST


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 :)

-Mike

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