• Divyesh Shah's avatar
    blkio: Add io_merged stat · 812d4026
    Divyesh Shah authored
    This includes both the number of bios merged into requests belonging to this
    cgroup as well as the number of requests merged together.
    In the past, we've observed different merging behavior across upstream kernels,
    some by design some actual bugs. This stat helps a lot in debugging such
    problems when applications report decreased throughput with a new kernel
    This needed adding an extra elevator function to capture bios being merged as I
    did not want to pollute elevator code with blkiocg knowledge and hence needed
    the accounting invocation to come from CFQ.
    Signed-off-by: default avatarDivyesh <Shah&lt;dpshah@google.com>
    Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>