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authorChris Mason <chris.mason@oracle.com>2008-11-10 13:08:31 -0500
committerChris Mason <chris.mason@oracle.com>2008-11-10 13:08:31 -0500
commit240d5d482b69415b92ffce4b8dfca10799c9890b (patch)
tree16320929e2220a7859d187bf4eda3810d2886bf2 /fs/btrfs/disk-io.c
parentb47eda8690a10f4fc01eb7b795078fa3fa57149f (diff)
Btrfs: tune btrfs unplug functions for a small number of devices
When btrfs unplugs, it tries to find the correct device to unplug via search through the extent_map tree. This avoids unplugging a device that doesn't need it, but is a waste of time for filesystems with a small number of devices. This patch checks the total number of devices before doing the search. Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/disk-io.c')
-rw-r--r--fs/btrfs/disk-io.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8efc123d222b..1bb54d69fbb2 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1201,6 +1201,16 @@ void btrfs_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1201 return; 1201 return;
1202 1202
1203 inode = mapping->host; 1203 inode = mapping->host;
1204
1205 /*
1206 * don't do the expensive searching for a small number of
1207 * devices
1208 */
1209 if (BTRFS_I(inode)->root->fs_info->fs_devices->open_devices <= 2) {
1210 __unplug_io_fn(bdi, page);
1211 return;
1212 }
1213
1204 offset = page_offset(page); 1214 offset = page_offset(page);
1205 1215
1206 em_tree = &BTRFS_I(inode)->extent_tree; 1216 em_tree = &BTRFS_I(inode)->extent_tree;