• Mikulas Patocka's avatar
    dm kcopyd: introduce configurable throttling · df5d2e90
    Mikulas Patocka authored
    This patch allows the administrator to reduce the rate at which kcopyd
    issues I/O.
    
    Each module that uses kcopyd acquires a throttle parameter that can be
    set in /sys/module/*/parameters.
    
    We maintain a history of kcopyd usage by each module in the variables
    io_period and total_period in struct dm_kcopyd_throttle. The actual
    kcopyd activity is calculated as a percentage of time equal to
    "(100 * io_period / total_period)".  This is compared with the user-defined
    throttle percentage threshold and if it is exceeded, we sleep.
    Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
    Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
    df5d2e90
dm-kcopyd.h 2.85 KB