Btrfs: optimize fsync for the single writer case
This patch optimizes the tree logging stuff so it doesn't always wait 1 jiffie
for new people to join the logging transaction if there is only ever 1 writer.
This helps a little bit with latency where we have something like RPM where it
will fdatasync every file it writes, and so waiting the 1 jiffie for every
fdatasync really starts to add up.
Signed-off-by: Josef Bacik <jbacik@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a362dd6..16ddb19 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1010,6 +1010,8 @@
atomic_t log_commit[2];
unsigned long log_transid;
unsigned long log_batch;
+ pid_t log_start_pid;
+ bool log_multiple_pids;
u64 objectid;
u64 last_trans;