Hi all, this series adds multiqueue support to the virtio-scsi driver, based on Jason Wang's work on virtio-net. It uses a simple queue steering algorithm that expects one queue per CPU. LUNs in the same target always use the same queue (so that commands are not reordered); queue switching occurs when the request being queued is the only one for the target. Also based on Jason's patches, the virtqueue affinity is set so that each CPU is associated to one virtqueue. I tested the patches with fio, using up to 32 virtio-scsi disks backed by tmpfs on the host, and 1 LUN per target. FIO configuration ----------------- [global] rw=read bsrange=4k-64k ioengine=libaio direct=1 iodepth=4 loops=20 overall bandwidth (MB/s) ----------------- # of targets single-queue multi-queue, 4 VCPUs multi-queue, 8 VCPUs 1 540 626 599 2 795 965 925 4 997 1376 1500 8 1136 2130 2060 16 1440 2269 2474 24 1408 2179 2436 32 1515 1978 2319 (These numbers for single-queue are with 4 VCPUs, but the impact of adding more VCPUs is very limited). avg bandwidth per LUN (MB/s) --------------------- # of targets single-queue multi-queue, 4 VCPUs multi-queue, 8 VCPUs 1 540 626 599 2 397 482 462 4 249 344 375 8 142 266 257 16 90 141 154 24 58 90 101 32 47 61 72 Testing this may require an irqbalance daemon that is built from git, due to http://code.google.com/p/irqbalance/issues/detail?id=37. Alternatively you can just set the affinity manually in /proc. Rusty, can you please give your Acked-by to the first two patches? Jason Wang (2): virtio-ring: move queue_index to vring_virtqueue virtio: introduce an API to set affinity for a virtqueue Paolo Bonzini (3): virtio-scsi: allocate target pointers in a separate memory block virtio-scsi: pass struct virtio_scsi to virtqueue completion function virtio-scsi: introduce multiqueue support drivers/lguest/lguest_device.c | 1 + drivers/remoteproc/remoteproc_virtio.c | 1 + drivers/s390/kvm/kvm_virtio.c | 1 + drivers/scsi/virtio_scsi.c | 200 ++++++++++++++++++++++++-------- drivers/virtio/virtio_mmio.c | 11 +- drivers/virtio/virtio_pci.c | 58 ++++++++- drivers/virtio/virtio_ring.c | 17 +++ include/linux/virtio.h | 4 + include/linux/virtio_config.h | 21 ++++ 9 files changed, 253 insertions(+), 61 deletions(-) _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
