virtio-blk: support mq_ops->queue_rqs()
This patch supports mq_ops->queue_rqs() hook. It has an advantage of batch submission to virtio-blk driver. It also helps polling I/O because polling uses batched completion of block layer. Batch submission in queue_rqs() can boost polling performance. In queue_rqs(), it iterates plug->mq_list, collects requests that belong to same HW queue until it encounters a request from other HW queue or sees the end of the list. Then, virtio-blk adds requests into virtqueue and kicks virtqueue to submit requests. If there is an error, it inserts error request to requeue_list and passes it to ordinary block layer path. For verification, I did fio test. (io_uring, randread, direct=1, bs=4K, iodepth=64 numjobs=N) I set 4 vcpu and 2 virtio-blk queues for VM and run fio test 5 times. It shows about 2% improvement. | numjobs=2 | numjobs=4 ----------------------------------------------------------- fio without queue_rqs() | 291K IOPS | 238K IOPS ----------------------------------------------------------- fio with queue_rqs() | 295K IOPS | 243K IOPS For polling I/O performance, I also did fio test as below. (io_uring, hipri, randread, direct=1, bs=512, iodepth=64 numjobs=4) I set 4 vcpu and 2 poll queues for VM. It shows about 2% improvement in polling I/O. | IOPS | avg latency ----------------------------------------------------------- fio poll without queue_rqs() | 424K | 613.05 usec ----------------------------------------------------------- fio poll with queue_rqs() | 435K | 601.01 usec Reviewed-by:Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
Suwan Kim <suwan.kim027@gmail.com> Message-Id: <20220406153207.163134-3-suwan.kim027@gmail.com> Signed-off-by:
Michael S. Tsirkin <mst@redhat.com> Reviewed-by:
Chaitanya Kulkarni <kch@nvidia.com>
parent
4e040052