Commit-ID: b402b73b3afe3614bc0e921ebe18013ea103115a
Gitweb: http://git.kernel.org/tip/b402b73b3afe3614bc0e921ebe18013ea103115a
Author: Dimitri Sivanich <sivanich@xxxxxxx>
AuthorDate: Fri, 29 Jun 2012 14:17:29 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Sun, 23 Sep 2012 07:41:53 -0700
rcu: Segregate rcu_state fields to improve cache locality
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@xxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Tested-by: Dimitri Sivanich <sivanich@xxxxxxx>
Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
---
kernel/rcutree.h | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
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. */
--
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