path: root/fs/btrfs/extent_io.h
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authorJosef Bacik <josef@redhat.com>2011-09-26 13:58:47 -0400
committerJosef Bacik <josef@redhat.com>2011-10-19 15:12:48 -0400
commit1728366efa5ebf48bd2ed544afa8700cd07ba822 (patch)
tree1f5d2129f3db9a9e8c3aa96b0c8120a55aac925c /fs/btrfs/extent_io.h
parent462d6fac8960a3ba797927adfcbd29d503eb16fd (diff)
Btrfs: stop using write_one_page
While looking for a performance regression a user was complaining about, I noticed that we had a regression with the varmail test of filebench. This was introduced by 0d10ee2e6deb5c8409ae65b970846344897d5e4e which keeps us from calling writepages in writepage. This is a correct change, however it happens to help the varmail test because we write out in larger chunks. This is largly to do with how we write out dirty pages for each transaction. If you run filebench with load varmail set $dir=/mnt/btrfs-test run 60 prior to this patch you would get ~1420 ops/second, but with the patch you get ~1200 ops/second. This is a 16% decrease. So since we know the range of dirty pages we want to write out, don't write out in one page chunks, write out in ranges. So to do this we call filemap_fdatawrite_range() on the range of bytes. Then we convert the DIRTY extents to NEED_WAIT extents. When we then call btrfs_wait_marked_extents() we only have to filemap_fdatawait_range() on that range and clear the NEED_WAIT extents. This doesn't get us back to our original speeds, but I've been seeing ~1380 ops/second, which is a <5% regression as opposed to a >15% regression. That is acceptable given that the original commit greatly reduces our latency to begin with. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com>
Diffstat (limited to 'fs/btrfs/extent_io.h')
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index cea445dcd80..325a346369d 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -17,6 +17,7 @@
#define EXTENT_NODATASUM (1 << 10)
#define EXTENT_DO_ACCOUNTING (1 << 11)
#define EXTENT_FIRST_DELALLOC (1 << 12)
+#define EXTENT_NEED_WAIT (1 << 13)