diff options
| author | Stefan Hajnoczi <stefanha@redhat.com> | 2020-08-18 15:33:47 +0100 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2020-08-27 08:29:13 -0400 |
| commit | 9445e1e15e66c19e42bea942ba810db28052cd05 (patch) | |
| tree | 04f90ede63d0f327c660fefbbc45f04c610ec429 /hw/block/virtio-blk.c | |
| parent | 6a558822849fab604a1fcb71e7c4e528cafa21d9 (diff) | |
virtio-blk-pci: default num_queues to -smp N
Automatically size the number of virtio-blk-pci request virtqueues to
match the number of vCPUs. Other transports continue to default to 1
request virtqueue.
A 1:1 virtqueue:vCPU mapping ensures that completion interrupts are
handled on the same vCPU that submitted the request. No IPI is
necessary to complete an I/O request and performance is improved. The
maximum number of MSI-X vectors and virtqueues limit are respected.
Performance improves from 78k to 104k IOPS on a 32 vCPU guest with 101
virtio-blk-pci devices (ioengine=libaio, iodepth=1, bs=4k, rw=randread
with NVMe storage).
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Message-Id: <20200818143348.310613-7-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw/block/virtio-blk.c')
| -rw-r--r-- | hw/block/virtio-blk.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 413783693c..2204ba149e 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -1147,6 +1147,9 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp) error_setg(errp, "Device needs media, but drive is empty"); return; } + if (conf->num_queues == VIRTIO_BLK_AUTO_NUM_QUEUES) { + conf->num_queues = 1; + } if (!conf->num_queues) { error_setg(errp, "num-queues property must be larger than 0"); return; @@ -1281,7 +1284,8 @@ static Property virtio_blk_properties[] = { #endif DEFINE_PROP_BIT("request-merging", VirtIOBlock, conf.request_merging, 0, true), - DEFINE_PROP_UINT16("num-queues", VirtIOBlock, conf.num_queues, 1), + DEFINE_PROP_UINT16("num-queues", VirtIOBlock, conf.num_queues, + VIRTIO_BLK_AUTO_NUM_QUEUES), DEFINE_PROP_UINT16("queue-size", VirtIOBlock, conf.queue_size, 256), DEFINE_PROP_BOOL("seg-max-adjust", VirtIOBlock, conf.seg_max_adjust, true), DEFINE_PROP_LINK("iothread", VirtIOBlock, conf.iothread, TYPE_IOTHREAD, |