On Mon, 6 Jul 2020 14:56:48 +0100 Stefan Hajnoczi <[email protected]> wrote:
Maybe mention 'pci' in the subject as well? > Automatically size the number of virtio-scsi-pci, vhost-scsi-pci, and > vhost-user-scsi-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. > > Signed-off-by: Stefan Hajnoczi <[email protected]> > --- > include/hw/virtio/virtio-scsi.h | 2 ++ > hw/core/machine.c | 3 +++ > hw/scsi/vhost-scsi.c | 3 ++- > hw/scsi/vhost-user-scsi.c | 3 ++- > hw/scsi/virtio-scsi.c | 6 +++++- > hw/virtio/vhost-scsi-pci.c | 10 +++++++--- > hw/virtio/vhost-user-scsi-pci.c | 10 +++++++--- > hw/virtio/virtio-scsi-pci.c | 10 +++++++--- > 8 files changed, 35 insertions(+), 12 deletions(-) (...) > diff --git a/hw/virtio/virtio-scsi-pci.c b/hw/virtio/virtio-scsi-pci.c > index 3ff9eb7ef6..fa4b3bfb50 100644 > --- a/hw/virtio/virtio-scsi-pci.c > +++ b/hw/virtio/virtio-scsi-pci.c > @@ -46,13 +46,17 @@ static void virtio_scsi_pci_realize(VirtIOPCIProxy > *vpci_dev, Error **errp) > { > VirtIOSCSIPCI *dev = VIRTIO_SCSI_PCI(vpci_dev); > DeviceState *vdev = DEVICE(&dev->vdev); > - VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev); > DeviceState *proxy = DEVICE(vpci_dev); > + VirtIOSCSIConf *conf = &dev->vdev.parent_obj.conf; > char *bus_name; > > + if (conf->num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) { > + conf->num_queues = > + virtio_pci_optimal_num_queues(VIRTIO_SCSI_VQ_NUM_FIXED); > + } > + > if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) { > - vpci_dev->nvectors = vs->conf.num_queues + > - VIRTIO_SCSI_VQ_NUM_FIXED + 1; > + vpci_dev->nvectors = conf->num_queues + VIRTIO_SCSI_VQ_NUM_FIXED + 1; > } > > /* One corner case where the setup may end up being a bit odd is a situation where nvectors was specified, but num_queues was not, and the device suddenly ends up with more queues than vectors. But I don't see a reason why you would want to specify nvectors but not num_queues in a real word scenario, so I think we can ignore that corner case. Reviewed-by: Cornelia Huck <[email protected]>
