This patch allows virtio-blk to release its block queue lock while kicking the host. This improves scalability on SMP guests who would otherwise spin on the lock while another vCPU is kicking the host.
This approach can be used for other virtio devices too. It simply splits the virtqueue_kick() operation into a prepare step which requires that the lock be held and the actual notify step which may be performed without the lock. Existing virtio drivers may continue to use the virtqueue_kick() interface which now does the prepare and notify steps internally. I am sending this out as RFC because further performance benchmarking is required. Although we have seen good results in the past, gathering number on a wider range of machines and verifying that there is no regression would be helpful. Stefan Hajnoczi (2): virtio_ring: split virtqueue_kick prepare/notify virtio_blk: unlock vblk->lock during kick drivers/block/virtio_blk.c | 10 ++++++++-- drivers/virtio/virtio_ring.c | 28 +++++++++++++++++++++------- include/linux/virtio.h | 13 +++++++++++++ 3 files changed, 42 insertions(+), 9 deletions(-) -- 1.7.5.4 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
