• Dave Chinner's avatar
    xfs: convert ENOSPC inode flushing to use new syncd workqueue · 89e4cb55
    Dave Chinner authored
    On of the problems with the current inode flush at ENOSPC is that we
    queue a flush per ENOSPC event, regardless of how many are already
    queued. Thi can result in    hundreds of queued flushes, most of
    which simply burn CPU scanned and do no real work. This simply slows
    down allocation at ENOSPC.
    
    We really only need one active flush at a time, and we can easily
    implement that via the new xfs_syncd_wq. All we need to do is queue
    a flush if one is not already active, then block waiting for the
    currently active flush to complete. The result is that we only ever
    have a single ENOSPC inode flush active at a time and this greatly
    reduces the overhead of ENOSPC processing.
    
    On my 2p test machine, this results in tests exercising ENOSPC
    conditions running significantly faster - 042 halves execution time,
    083 drops from 60s to 5s, etc - while not introducing test
    regressions.
    
    This allows us to remove the old xfssyncd threads and infrastructure
    as they are no longer used.
    Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
    Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
    Reviewed-by: default avatarAlex Elder <aelder@sgi.com>
    89e4cb55
xfs_mount.h 15.1 KB