Hi, As recent discussion, especially suggested by Christoph, this patchset implements per-distpatch_queue flush machinery, so that: - current init_request and exit_request callbacks can cover flush request too, then the ugly and buggy copying way of initializing flush request's pdu can be fixed - flushing performance gets improved in case of multi hw-queue About 70% throughput improvement is observed in sync write/randwrite over multi dispatch-queue virtio-blk, see details in commit log of patch 8/8. This patchset can be pulled from below tree too: git://kernel.ubuntu.com/ming/linux.git v3.17-block-dev block/blk-core.c | 11 +-- block/blk-flush.c | 239 +++++++++++++++++++++++++++++++++++++++--------- block/blk-mq.c | 27 +++--- block/blk-mq.h | 1 - block/blk-sysfs.c | 4 +- block/blk.h | 35 ++++++- include/linux/blk-mq.h | 2 + include/linux/blkdev.h | 10 +- 8 files changed, 251 insertions(+), 78 deletions(-) Thanks, -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html