This patch introduces parameter of 'num_queues',
so that virtio-blk can support multi virt queues.
The virtio-blk multi virtqueue feature will be added to
virtio spec 1.1[1], and the 3.17 linux kernel[2] will support
the feature in virtio-blk driver. For those who wants to play
the stuff now, the kernel side patches can be found in either
Jens's block tree[3] or linux-next[4].
In my fio test over VM which is hosted on the server host,
if "num_queues" is set as 4, JOBS of fio script is set
as 4, throughout can be improved by 25% compared with
single virtqueue with any JOBS.
Compared with throughput, scalability is improved much more,
for example:
---------------------------------------------------
| VM in server host, 4 virtqueues vs. 1 virtqueue
---------------------------------------------------
JOBS=2 | +10%
---------------------------------------------------
JOBS=4 | +78%
---------------------------------------------------
[1], http://marc.info/?l=linux-api&m=140486843317107&w=2
[2], http://marc.info/?l=linux-api&m=140418368421229&w=2
[3], http://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git/
#for-3.17/drivers
[4], https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/
Signed-off-by: Ming Lei <ming....@canonical.com>
---
hw/block/virtio-blk.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index baec8f8..58f8296 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -834,6 +834,7 @@ static Property virtio_blk_properties[] = {
DEFINE_BLOCK_CHS_PROPERTIES(VirtIOBlock, blk.conf),
DEFINE_PROP_STRING("serial", VirtIOBlock, blk.serial),
DEFINE_PROP_BIT("config-wce", VirtIOBlock, blk.config_wce, 0, true),
+ DEFINE_PROP_UINT32("num_queues", VirtIOBlock, blk.num_queues, 1),
#ifdef __linux__
DEFINE_PROP_BIT("scsi", VirtIOBlock, blk.scsi, 0, true),
#endif
--
1.7.9.5
