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[PATCH v5 4/5] virtio-blk: default num_queues to -smp N
From: |
Stefan Hajnoczi |
Subject: |
[PATCH v5 4/5] virtio-blk: default num_queues to -smp N |
Date: |
Mon, 6 Jul 2020 14:56:49 +0100 |
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>
---
include/hw/virtio/virtio-blk.h | 2 ++
hw/block/virtio-blk.c | 6 +++++-
hw/core/machine.c | 1 +
hw/virtio/virtio-blk-pci.c | 7 ++++++-
4 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
index b1334c3904..7539c2b848 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;
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,
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 3df534405b..845f6476cb 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -32,6 +32,7 @@ GlobalProperty hw_compat_5_0[] = {
{ "vhost-scsi", "num_queues", "1"},
{ "vhost-user-scsi", "num_queues", "1"},
{ "virtio-balloon-device", "page-poison", "false" },
+ { "virtio-blk-device", "num-queues", "1"},
{ "virtio-scsi-device", "num_queues", "1"},
{ "vmport", "x-read-set-eax", "off" },
{ "vmport", "x-signal-unsupported-cmd", "off" },
diff --git a/hw/virtio/virtio-blk-pci.c b/hw/virtio/virtio-blk-pci.c
index 849cc7dfd8..37c6e0aeb4 100644
--- a/hw/virtio/virtio-blk-pci.c
+++ b/hw/virtio/virtio-blk-pci.c
@@ -50,9 +50,14 @@ static void virtio_blk_pci_realize(VirtIOPCIProxy *vpci_dev,
Error **errp)
{
VirtIOBlkPCI *dev = VIRTIO_BLK_PCI(vpci_dev);
DeviceState *vdev = DEVICE(&dev->vdev);
+ VirtIOBlkConf *conf = &dev->vdev.conf;
+
+ if (conf->num_queues == VIRTIO_BLK_AUTO_NUM_QUEUES) {
+ conf->num_queues = virtio_pci_optimal_num_queues(0);
+ }
if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
- vpci_dev->nvectors = dev->vdev.conf.num_queues + 1;
+ vpci_dev->nvectors = conf->num_queues + 1;
}
qdev_realize(vdev, BUS(&vpci_dev->bus), errp);
--
2.26.2
[PATCH v5 1/5] virtio-pci: add virtio_pci_optimal_num_queues() helper, Stefan Hajnoczi, 2020/07/06
[PATCH v5 4/5] virtio-blk: default num_queues to -smp N,
Stefan Hajnoczi <=
[PATCH v5 5/5] vhost-user-blk: default num_queues to -smp N, Stefan Hajnoczi, 2020/07/06
Re: [PATCH v5 0/5] virtio-pci: enable blk and scsi multi-queue by default, Michael S. Tsirkin, 2020/07/08