From 9445e1e15e66c19e42bea942ba810db28052cd05 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 18 Aug 2020 15:33:47 +0100 Subject: 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 Reviewed-by: Cornelia Huck Reviewed-by: Pankaj Gupta Message-Id: <20200818143348.310613-7-stefanha@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- include/hw/virtio/virtio-blk.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/hw') diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h index b1334c3..7539c2b 100644 --- a/include/hw/virtio/virtio-blk.h +++ b/include/hw/virtio/virtio-blk.h @@ -30,6 +30,8 @@ struct virtio_blk_inhdr unsigned char status; }; +#define VIRTIO_BLK_AUTO_NUM_QUEUES UINT16_MAX + struct VirtIOBlkConf { BlockConf conf; -- cgit v1.1