Hi,
> Currently fdatasync is identical to fsync in ext3,4.
> 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 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.
>
> Thanks.
>
> Signed-off-by :Hisashi Hifumi <[EMAIL PROTECTED]>
Yes, the patch looks fine. You can add
Acked-by: Jan Kara <[EMAIL PROTECTED]>
if you wish.
Honza
> diff -Nrup linux-2.6.24.org/fs/ext3/fsync.c linux-2.6.24/fs/ext3/fsync.c
> --- linux-2.6.24.org/fs/ext3/fsync.c 2008-01-25 07:58:37.000000000 +0900
> +++ linux-2.6.24/fs/ext3/fsync.c 2008-02-04 12:42:42.000000000 +0900
> @@ -72,6 +72,9 @@ int ext3_sync_file(struct file * file, s
> goto out;
> }
>
> + if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
> + goto out;
> +
> /*
> * The VFS has written the file data. If the inode is unaltered
> * then we need not start a commit.
> diff -Nrup linux-2.6.24.org/fs/ext4/fsync.c linux-2.6.24/fs/ext4/fsync.c
> --- linux-2.6.24.org/fs/ext4/fsync.c 2008-01-25 07:58:37.000000000 +0900
> +++ linux-2.6.24/fs/ext4/fsync.c 2008-02-04 12:43:37.000000000 +0900
> @@ -72,6 +72,9 @@ int ext4_sync_file(struct file * file, s
> goto out;
> }
>
> + if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
> + goto out;
> +
> /*
> * The VFS has written the file data. If the inode is unaltered
> * then we need not start a commit.
>
> -
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--
Jan Kara <[EMAIL PROTECTED]>
SuSE CR Labs
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