• Zhang Yi's avatar
    jbd2: fix checkpoint cleanup performance regression · 373ac521
    Zhang Yi authored
    journal_clean_one_cp_list() has been merged into
    journal_shrink_one_cp_list(), but do chekpoint buffer cleanup from the
    committing process is just a best effort, it should stop scan once it
    meet a busy buffer, or else it will cause a lot of invalid buffer scan
    and checks. We catch a performance regression when doing fs_mark tests
    below.
    
    Test cmd:
     ./fs_mark  -d  scratch  -s  1024  -n  10000  -t  1  -D  100  -N  100
    
    Before merging checkpoint buffer cleanup:
     FSUse%        Count         Size    Files/sec     App Overhead
         95        10000         1024       8304.9            49033
    
    After merging checkpoint buffer cleanup:
     FSUse%        Count         Size    Files/sec     App Overhead
         95        10000         1024       7649.0            50012
     FSUse%        Count         Size    Files/sec     App Overhead
         95        10000         1024       2107.1            50871
    
    After merging checkpoint buffer cleanup, the total loop count in
    journal_shrink_one_cp_list() could be up to 6,261,600+ (50,000+ ~
    100,000+ in general), most of them are invalid. This patch fix it
    through passing 'shrink_type' into journal_shrink_one_cp_list() and add
    a new 'SHRINK_BUSY_STOP' to indicate it should stop once meet a busy
    buffer. After fix, the loop count descending back to 10,000+.
    
    After this fix:
     FSUse%        Count         Size    Files/sec     App Overhead
         95        10000         1024       8558.4            49109
    
    Cc: stable@kernel.org
    Fixes: b98dba27 ("jbd2: remove journal_clean_one_cp_list()")
    Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
    Reviewed-by: default avatarJan Kara <jack@suse.cz>
    Link: https://lore.kernel.org/r/20230714025528.564988-2-yi.zhang@huaweicloud.comSigned-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
    373ac521
checkpoint.c 20.9 KB