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rcu: increment quiescent state counter in ksoftirqd()

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If a machine is flooded by network frames, a cpu can loop
100% of its time inside ksoftirqd() without calling schedule().
This can delay RCU grace period to insane values.

Adding rcu_qsctr_inc() call in ksoftirqd() solves this problem.

Paul: "This regression was a result of the recent change from
"schedule()" to "cond_resched()", which got rid of that quiescent
state in the common case where a reschedule is not needed".

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Eric Dumazet 2009-03-04 12:11:56 -08:00 committed by Ingo Molnar
parent 559595a985
commit 64ca5ab913
1 changed files with 1 additions and 0 deletions
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kernel/softirq.c
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@ -626,6 +626,7 @@ static int ksoftirqd(void * __bind_cpu)
preempt_enable_no_resched();
cond_resched();
preempt_disable();
rcu_qsctr_inc((long)__bind_cpu);
}
preempt_enable();
set_current_state(TASK_INTERRUPTIBLE);