f2fs: introduce sysfs readdir_ra to readahead inode block in readdir
This patch introduces a sysfs interface readdir_ra to enable/disable
readaheading inode block in f2fs_readdir. When readdir_ra is enabled,
it improves the performance of "readdir + stat".
For 300,000 files:
time find /data/test > /dev/null
disable readdir_ra: 1m25.69s real 0m01.94s user 0m50.80s system
enable readdir_ra: 0m18.55s real 0m00.44s user 0m15.39s system
Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index a7799c2..d870b55 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -186,3 +186,9 @@
Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
Description:
Controls sleep time of GC urgent mode
+
+What: /sys/fs/f2fs/<disk>/readdir_ra
+Date: November 2017
+Contact: "Sheng Yong" <shengyong1@huawei.com>
+Description:
+ Controls readahead inode block in readdir.