• Mikulas Patocka's avatar
    dm snapshot: use dm-bufio prefetch · 55b082e6
    Mikulas Patocka authored
    This patch modifies dm-snapshot so that it prefetches the buffers when
    loading the exceptions.
    
    The number of buffers read ahead is specified in the DM_PREFETCH_CHUNKS
    macro.  The current value for DM_PREFETCH_CHUNKS (12) was found to
    provide the best performance on a single 15k SCSI spindle.  In the
    future we may modify this default or make it configurable.
    
    Also, introduce the function dm_bufio_set_minimum_buffers to setup
    bufio's number of internal buffers before freeing happens.  dm-bufio may
    hold more buffers if enough memory is available.  There is no guarantee
    that the specified number of buffers will be available - if you need a
    guarantee, use the argument reserved_buffers for
    dm_bufio_client_create.
    Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
    Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
    55b082e6
dm-bufio.c 44.6 KB