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authorJaegeuk Kim <jaegeuk.kim@samsung.com>2014-04-02 15:34:36 +0900
committerJaegeuk Kim <jaegeuk.kim@samsung.com>2014-04-07 09:50:58 +0900
commit6b4afdd794783fe515b50838aa36591e3feea990 (patch)
tree5f35f32e27db8deaf248cf1e7a4930aab0822a73 /Documentation/filesystems
parentce23447fe5764391025a67c20c97eaf5c6ac1ec3 (diff)
f2fs: introduce f2fs_issue_flush to avoid redundant flush issue
Some storage devices show relatively high latencies to complete cache_flush commands, even though their normal IO speed is prettry much high. In such the case, it needs to merge cache_flush commands as much as possible to avoid issuing them redundantly. So, this patch introduces a mount option, "-o flush_merge", to mitigate such the overhead. If this option is enabled by user, F2FS merges the cache_flush commands and then issues just one cache_flush on behalf of them. Once the single command is finished, F2FS sends a completion signal to all the pending threads. Note that, this option can be used under a workload consisting of very intensive concurrent fsync calls, while the storage handles cache_flush commands slowly. Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/f2fs.txt4
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
index 2f6d0218dd22..25311e113e75 100644
--- 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.
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