[PATCH V5 0/4] Improve virtio-blk performance

[Asias He <asias@redhat.com>]

Hi folks,

This version added REQ_FLUSH and REQ_FUA support as suggested by Christoph and
rebased against latest linus's tree. 

Jens, could you please consider picking up the dependencies 1/4 and 2/4 in your
tree. Thanks!

This patchset implements bio-based IO path for virito-blk to improve
performance.

Fio test shows bio-based IO path gives the following performance improvement:

1) Ramdisk device
     With bio-based IO path, sequential read/write, random read/write
     IOPS boost         : 28%, 24%, 21%, 16%
     Latency improvement: 32%, 17%, 21%, 16%
2) Fusion IO device
     With bio-based IO path, sequential read/write, random read/write
     IOPS boost         : 11%, 11%, 13%, 10%
     Latency improvement: 10%, 10%, 12%, 10%

Asias He (4):
  block: Introduce __blk_segment_map_sg() helper
  block: Add blk_bio_map_sg() helper
  virtio-blk: Add bio-based IO path for virtio-blk
  virtio-blk: Add REQ_FLUSH and REQ_FUA support to bio path

 block/blk-merge.c          | 117 +++++++++++++------
 drivers/block/virtio_blk.c | 279 ++++++++++++++++++++++++++++++++++++++-------
 include/linux/blkdev.h     |   2 +
 3 files changed, 324 insertions(+), 74 deletions(-)

-- 
1.7.11.2