• Jaegeuk Kim's avatar
    f2fs: improve write performance under frequent fsync calls · fb5566da
    Jaegeuk Kim authored
    When considering a bunch of data writes with very frequent fsync calls, we
    are able to think the following performance regression.
    
    N: Node IO, D: Data IO, IO scheduler: cfq
    
    Issue    pending IOs
    	 D1 D2 D3 D4
     D1         D2 D3 D4 N1
     D2            D3 D4 N1 N2
     N1            D3 D4 N2 D1
     --> N1 can be selected by cfq becase of the same priority of N and D.
         Then D3 and D4 would be delayed, resuling in performance degradation.
    
    So, when processing the fsync call, it'd better give higher priority to data IOs
    than node IOs by assigning WRITE and WRITE_SYNC respectively.
    This patch improves the random wirte performance with frequent fsync calls by up
    to 10%.
    Signed-off-by: default avatarJaegeuk Kim <jaegeuk.kim@samsung.com>
    fb5566da
file.c 15.6 KB