Btrfs: Lower contention on the csum mutex

This takes the csum mutex deeper in the call chain and releases it
more often.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1aed1f4616b6..92e14dd9bddb 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1386,7 +1386,14 @@ struct btrfs_root *open_ctree(struct super_block *sb,
          * devices
          */
         fs_info->submit_workers.idle_thresh = 64;
-        fs_info->workers.idle_thresh = 32;
+
+        /* fs_info->workers is responsible for checksumming file data
+         * blocks and metadata.  Using a larger idle thresh allows each
+         * worker thread to operate on things in roughly the order they
+         * were sent by the writeback daemons, improving overall locality
+         * of the IO going down the pipe.
+         */
+        fs_info->workers.idle_thresh = 128;
 
         btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1);
         btrfs_init_workers(&fs_info->endio_workers, "endio",