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Re: [PATCH v2 2/4] virtio-scsi: default num_queues to -smp N
From: |
Stefan Hajnoczi |
Subject: |
Re: [PATCH v2 2/4] virtio-scsi: default num_queues to -smp N |
Date: |
Wed, 29 Jan 2020 15:44:38 +0000 |
On Mon, Jan 27, 2020 at 02:10:31PM +0100, Cornelia Huck wrote:
> On Fri, 24 Jan 2020 10:01:57 +0000
> Stefan Hajnoczi <address@hidden> wrote:
> > @@ -47,10 +48,15 @@ static void vhost_scsi_pci_realize(VirtIOPCIProxy
> > *vpci_dev, Error **errp)
> > {
> > VHostSCSIPCI *dev = VHOST_SCSI_PCI(vpci_dev);
> > DeviceState *vdev = DEVICE(&dev->vdev);
> > - VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
> > + VirtIOSCSIConf *conf = &dev->vdev.parent_obj.parent_obj.conf;
> > +
> > + /* 1:1 vq to vcpu mapping is ideal because it avoids IPIs */
> > + if (conf->num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) {
> > + conf->num_queues = current_machine->smp.cpus;
>
> This now maps the request vqs 1:1 to the vcpus. What about the fixed
> vqs? If they don't really matter, amend the comment to explain that?
The fixed vqs don't matter. They are typically not involved in the data
path, only the control path where performance doesn't matter.
Stefan
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[PATCH v2 3/4] virtio-blk: default num_queues to -smp N, Stefan Hajnoczi, 2020/01/24
[PATCH v2 4/4] vhost-user-blk: default num_queues to -smp N, Stefan Hajnoczi, 2020/01/24
Re: [PATCH v2 0/4] virtio-pci: enable blk and scsi multi-queue by default, Stefano Garzarella, 2020/01/27