[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-mm-commits
Subject:    + rcu-increment-quiescent-state-counter-in-ksoftirqd.patch added to -mm tree
From:       akpm () linux-foundation ! org
Date:       2009-02-27 20:30:37
Message-ID: 200902272030.n1RKUbkR031645 () imap1 ! linux-foundation ! org
[Download RAW message or body]


The patch titled
     rcu: increment quiescent state counter in ksoftirqd()
has been added to the -mm tree.  Its filename is
     rcu-increment-quiescent-state-counter-in-ksoftirqd.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
Subject: rcu: increment quiescent state counter in ksoftirqd()
From: Eric Dumazet <dada1@cosmosbay.com>

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>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/softirq.c |    1 +
 1 file changed, 1 insertion(+)

diff -puN kernel/softirq.c~rcu-increment-quiescent-state-counter-in-ksoftirqd kernel/softirq.c
--- a/kernel/softirq.c~rcu-increment-quiescent-state-counter-in-ksoftirqd
+++ a/kernel/softirq.c
@@ -648,6 +648,7 @@ 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);
_

Patches currently in -mm which might be from dada1@cosmosbay.com are

linux-next.patch
rcu-increment-quiescent-state-counter-in-ksoftirqd.patch
softirq-introduce-statistics-for-softirq.patch
proc-export-statistics-for-softirq-to-proc.patch
proc-export-statistics-for-softirq-to-proc-fix.patch
proc-update-document-for-proc-softirqs-and-proc-stat.patch
workqueue-avoid-recursion-in-run_workqueue.patch

--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
[prev in list] [next in list] [prev in thread] [next in thread]