path: root/kernel/rcutree.h
diff options
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2009-10-14 10:15:55 -0700
committerIngo Molnar <mingo@elte.hu>2009-10-15 11:17:16 +0200
commit37c72e56f6b234ea7387ba530434a80abf2658d8 (patch)
tree1c589c3ecdebbe19488359795cde4c55726a63aa /kernel/rcutree.h
parent2bc872036e1c5948b5b02942810bbdd8dbdb9812 (diff)
rcu: Prevent RCU IPI storms in presence of high call_rcu() load
As the number of callbacks on a given CPU rises, invoke force_quiescent_state() only every blimit number of callbacks (defaults to 10,000), and even then only if no other CPU has invoked force_quiescent_state() in the meantime. This should fix the performance regression reported by Nick. Reported-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com Cc: jens.axboe@oracle.com LKML-Reference: <12555405592133-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcutree.h')
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index b40ac5706040..599161f309fb 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -167,6 +167,10 @@ struct rcu_data {
struct rcu_head *nxtlist;
struct rcu_head **nxttail[RCU_NEXT_SIZE];
long qlen; /* # of queued callbacks */
+ long qlen_last_fqs_check;
+ /* qlen at last check for QS forcing */
+ unsigned long n_force_qs_snap;
+ /* did other CPU force QS recently? */
long blimit; /* Upper limit on a processed batch */

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