Merge branch 'async-scsi-resume' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux.git] / Documentation / filesystems / f2fs.txt

diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
index b8d284975f0f074c5e2c5d6126e1cf33bb6798d4..25311e113e75415e1962b2e157d3e55d5023aa1c 100644 (file)
--- a/Documentation/filesystems/f2fs.txt
+++ b/Documentation/filesystems/f2fs.txt
@@ -122,6 +122,10 @@ disable_ext_identify   Disable the extension list configured by mkfs, so f2fs
 inline_xattr           Enable the inline xattrs feature.
 inline_data            Enable the inline data feature: New created small(<~3.4k)
                        files can be written into inode block.
+flush_merge           Merge concurrent cache_flush commands as much as possible
+                       to eliminate redundant command issues. If the underlying
+                      device handles the cache_flush command relatively slowly,
+                      recommend to enable this option.
 
 ================================================================================
 DEBUGFS ENTRIES
@@ -169,9 +173,11 @@ Files in /sys/fs/f2fs/<devname>
 
  reclaim_segments             This parameter controls the number of prefree
                               segments to be reclaimed. If the number of prefree
-                             segments is larger than this number, f2fs tries to
-                             conduct checkpoint to reclaim the prefree segments
-                             to free segments. By default, 100 segments, 200MB.
+                             segments is larger than the number of segments
+                             in the proportion to the percentage over total
+                             volume size, f2fs tries to conduct checkpoint to
+                             reclaim the prefree segments to free segments.
+                             By default, 5% over total # of segments.
 
  max_small_discards          This parameter controls the number of discard
                              commands that consist small blocks less than 2MB.
@@ -195,6 +201,17 @@ Files in /sys/fs/f2fs/<devname>
                              cleaning operations. The default value is 4096
                              which covers 8GB block address range.
 
+ dir_level                    This parameter controls the directory level to
+                             support large directory. If a directory has a
+                             number of files, it can reduce the file lookup
+                             latency by increasing this dir_level value.
+                             Otherwise, it needs to decrease this value to
+                             reduce the space overhead. The default value is 0.
+
+ ram_thresh                   This parameter controls the memory footprint used
+                             by free nids and cached nat entries. By default,
+                             10 is set, which indicates 10 MB / 1 GB RAM.
+
 ================================================================================
 USAGE
 ================================================================================
@@ -444,9 +461,11 @@ The number of blocks and buckets are determined by,
   # of blocks in level #n = |
                             `- 4, Otherwise
 
-                             ,- 2^n, if n < MAX_DIR_HASH_DEPTH / 2,
+                             ,- 2^ (n + dir_level),
+                            |            if n < MAX_DIR_HASH_DEPTH / 2,
   # of buckets in level #n = |
-                             `- 2^((MAX_DIR_HASH_DEPTH / 2) - 1), Otherwise
+                             `- 2^((MAX_DIR_HASH_DEPTH / 2 + dir_level) - 1),
+                                         Otherwise
 
 When F2FS finds a file name in a directory, at first a hash value of the file
 name is calculated. Then, F2FS scans the hash table in level #0 to find the