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 --- hw/core/machine.c | 1 + 1 file changed, 1 insertion(+) (limited to 'hw/core/machine.c') diff --git a/hw/core/machine.c b/hw/core/machine.c index 9ee2aa0f7b..7f65fa8743 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -31,6 +31,7 @@ GlobalProperty hw_compat_5_1[] = { { "vhost-scsi", "num_queues", "1"}, { "vhost-user-scsi", "num_queues", "1"}, + { "virtio-blk-device", "num-queues", "1"}, { "virtio-scsi-device", "num_queues", "1"}, }; const size_t hw_compat_5_1_len = G_N_ELEMENTS(hw_compat_5_1); -- cgit 1.4.1