• Mikulas Patocka's avatar
    dm-snapshot: fix performance degradation due to small hash size · 60e356f3
    Mikulas Patocka authored
    LVM2, since version 2.02.96, creates origin with zero size, then loads
    the snapshot driver and then loads the origin.  Consequently, the
    snapshot driver sees the origin size zero and sets the hash size to the
    lower bound 64.  Such small hash table causes performance degradation.
    
    This patch changes it so that the hash size is determined by the size of
    snapshot volume, not minimum of origin and snapshot size.  It doesn't
    make sense to set the snapshot size significantly larger than the origin
    size, so we do not need to take origin size into account when
    calculating the hash size.
    Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
    Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
    Cc: stable@vger.kernel.org
    60e356f3
dm-snap.c 52.5 KB