diff mbox

[tip/core/rcu,09/23] rcu: Segregate rcu_state fields to improve cache locality

Message ID 1348166900-18716-9-git-send-email-paulmck@linux.vnet.ibm.com
State Accepted
Commit b402b73b3afe3614bc0e921ebe18013ea103115a
Headers show

Commit Message

Paul E. McKenney Sept. 20, 2012, 6:48 p.m. UTC 
From: Dimitri Sivanich <sivanich@sgi.com>

The fields in the rcu_state structure that are protected by the
root rcu_node structure's ->lock can share a cache line with the
fields protected by ->onofflock.  This can result in excessive
memory contention on large systems, so this commit applies
____cacheline_internodealigned_in_smp to the ->onofflock field in
order to segregate them.

Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Dimitri Sivanich <sivanich@sgi.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
---
 kernel/rcutree.h |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
diff mbox

Patch

diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index effb273..5d92b80 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -394,7 +394,8 @@  struct rcu_state {
 
 	/* End of fields guarded by root rcu_node's lock. */
 
-	raw_spinlock_t onofflock;		/* exclude on/offline and */
+	raw_spinlock_t onofflock ____cacheline_internodealigned_in_smp;
+						/* exclude on/offline and */
 						/*  starting new GP. */
 	struct rcu_head *orphan_nxtlist;	/* Orphaned callbacks that */
 						/*  need a grace period. */