Commit 857f3fd7 authored Jul 11, 2008 by Heiko Carstens Committed by Ingo Molnar Jul 11, 2008

nohz: don't stop idle tick if softirqs are pending.



In case a cpu goes idle but softirqs are pending only an error message is
printed to the console. It may take a very long time until the pending
softirqs will finally be executed. Worst case would be a hanging system.

With this patch the timer tick just continues and the softirqs will be
executed after the next interrupt. Still a delay but better than a
hanging system.

Currently we have at least two device drivers on s390 which under certain
circumstances schedule a tasklet from process context. This is a reason
why we can end up with pending softirqs when going idle. Fixing these
drivers seems to be non-trivial.
However there is no question that the drivers should be fixed.
This patch shouldn't be considered as a bug fix. It just is intended to
keep a system running even if device drivers are buggy.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jan Glauber <jan.glauber@de.ibm.com>
Cc: Stefan Weinhuber <wein@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 7a14ce1d

kernel/time/tick-sched.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -235,6 +235,7 @@ void tick_nohz_stop_sched_tick(void)
		local_softirq_pending());
		ratelimit++;
		}
		goto end;
		}

		ts->idle_calls++;

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