• Junxiao Bi's avatar
    ocfs2: reflink: fix slow unlink for refcounted file · f62f12b3
    Junxiao Bi authored
    When running ocfs2 test suite multiple nodes reflink stress test, for a
    4 nodes cluster, every unlink() for refcounted file needs about 700s.
    
    The slow unlink is caused by the contention of refcount tree lock since
    all nodes are unlink files using the same refcount tree.  When the
    unlinking file have many extents(over 1600 in our test), most of the
    extents has refcounted flag set.  In ocfs2_commit_truncate(), it will
    execute the following call trace for every extents.  This means it needs
    get and released refcount tree lock about 1600 times.  And when several
    nodes are do this at the same time, the performance will be very low.
    
      ocfs2_remove_btree_range()
      --  ocfs2_lock_refcount_tree()
      ----  ocfs2_refcount_lock()
      ------  __ocfs2_cluster_lock()
    
    ocfs2_refcount_lock() is costly, move it to ocfs2_commit_truncate() to
    do lock/unlock once can improve a lot performance.
    Signed-off-by: default avatarJunxiao Bi <junxiao.bi@oracle.com>
    Cc: Wengang <wen.gang.wang@oracle.com>
    Reviewed-by: default avatarMark Fasheh <mfasheh@suse.de>
    Cc: Joel Becker <jlbec@evilplan.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    f62f12b3
alloc.h 11.8 KB