]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
ext3: fdatasync should skip metadata writeout when overwriting
authorHisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Mon, 28 Apr 2008 09:16:05 +0000 (02:16 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 28 Apr 2008 15:58:43 +0000 (08:58 -0700)
commit3d61f75eefedf75914ab4453c67aaa2ee64bcf93
tree7a6c2c461a05f36694466dac40f386b11d15dac2
parent8b91582500ae750db22bd515379616e5e9ad06ab
ext3: fdatasync should skip metadata writeout when overwriting

Currently fdatasync is identical to fsync in ext3.

I think fdatasync should skip journal flush in data=ordered and
data=writeback mode when it overwrites to already-instantiated blocks on
HDD.  When I_DIRTY_DATASYNC flag is not set, fdatasync should skip journal
writeout because this indicates only atime or/and mtime updates.

Following patch is the same approach of ext2's fsync code(ext2_sync_file).

I did a performance test using the sysbench.

#sysbench --num-threads=128 --max-requests=50000 --test=fileio --file-total-size=128G
--file-test-mode=rndwr --file-fsync-mode=fdatasync run

The result on ext3 was:

-2.6.24
Operations performed:  0 Read, 50080 Write, 59600 Other = 109680 Total
Read 0b  Written 782.5Mb  Total transferred 782.5Mb  (12.116Mb/sec)
  775.45 Requests/sec executed

Test execution summary:
    total time:                          64.5814s
    total number of events:              50080
    total time taken by event execution: 3713.9836
    per-request statistics:
         min:                            0.0000s
         avg:                            0.0742s
         max:                            0.9375s
         approx.  95 percentile:         0.2901s

Threads fairness:
    events (avg/stddev):           391.2500/23.26
    execution time (avg/stddev):   29.0155/1.99

-2.6.24-patched
Operations performed:  0 Read, 50009 Write, 61596 Other = 111605 Total
Read 0b  Written 781.39Mb  Total transferred 781.39Mb  (16.419Mb/sec)
1050.83 Requests/sec executed

Test execution summary:
    total time:                          47.5900s
    total number of events:              50009
    total time taken by event execution: 2934.5768
    per-request statistics:
           min:                            0.0000s
         avg:                            0.0587s
           max:                            0.8938s
         approx.  95 percentile:         0.1993s

Threads fairness:
    events (avg/stddev):           390.6953/22.64
    execution time (avg/stddev):   22.9264/1.17

Filesystem I/O throughput was improved.

Signed-off-by :Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Acked-by: Jan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/ext3/fsync.c