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authorChris Mason <chris.mason@oracle.com>2008-06-25 16:14:04 -0400
committerChris Mason <chris.mason@oracle.com>2008-09-25 11:04:04 -0400
commitf9efa9c784aa3b801feb367f72c6867d26fb348e (patch)
treed9f678310c6c8a4daf2003fa4f6b4164111dbbd7 /fs/btrfs/locking.c
parent3f157a2fd2ad731e1ed9964fecdc5f459f04a4a4 (diff)
downloadblackbird-op-linux-f9efa9c784aa3b801feb367f72c6867d26fb348e.tar.gz
blackbird-op-linux-f9efa9c784aa3b801feb367f72c6867d26fb348e.zip
Btrfs: Reduce contention on the root node
This calls unlock_up sooner in btrfs_search_slot in order to decrease the amount of work done with the higher level tree locks held. Also, it changes btrfs_tree_lock to spin for a big against the page lock before scheduling. This makes a big difference in context switch rate under highly contended workloads. Longer term, a better locking structure is needed than the page lock. Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/locking.c')
-rw-r--r--fs/btrfs/locking.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 80813a307b4b..058a506a0dd8 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -27,6 +27,16 @@
int btrfs_tree_lock(struct extent_buffer *eb)
{
+ int i;
+
+ if (!TestSetPageLocked(eb->first_page))
+ return 0;
+ for (i = 0; i < 512; i++) {
+ cpu_relax();
+ if (!TestSetPageLocked(eb->first_page))
+ return 0;
+ }
+ cpu_relax();
lock_page(eb->first_page);
return 0;
}
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