• Konstantin Khlebnikov's avatar
    block: add iostat counters for flush requests · b6866318
    Konstantin Khlebnikov authored
    Requests that triggers flushing volatile writeback cache to disk (barriers)
    have significant effect to overall performance.
    
    Block layer has sophisticated engine for combining several flush requests
    into one. But there is no statistics for actual flushes executed by disk.
    Requests which trigger flushes usually are barriers - zero-size writes.
    
    This patch adds two iostat counters into /sys/class/block/$dev/stat and
    /proc/diskstats - count of completed flush requests and their total time.
    Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
    Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
    b6866318
genhd.c 50.7 KB