diff mbox

virtio-net: calculate proper msix vectors on init

Message ID 1392958857-10965-1-git-send-email-jasowang@redhat.com
State New
Headers show

Commit Message

Jason Wang Feb. 21, 2014, 5 a.m. UTC
Currently, the default msix vectors for virtio-net-pci is 3 which is
obvious not suitable for multiqueue guest, so we depends on the user
or management tools to pass a correct vectors parameter. In fact, we
can simplifying this by calculate the number of vectors on init.

Consider we have N queues, the number of vectors needed is 2*N + 2
(plus one config interrupt and control vq). We didn't check whether or
not host support control vq because it was added unconditionally by
qemu to avoid breaking legacy guests such as Minix.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/virtio/virtio-pci.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

Comments

Jason Wang Feb. 21, 2014, 8:50 a.m. UTC | #1
On 02/21/2014 01:00 PM, Jason Wang wrote:
> Currently, the default msix vectors for virtio-net-pci is 3 which is
> obvious not suitable for multiqueue guest, so we depends on the user
> or management tools to pass a correct vectors parameter. In fact, we
> can simplifying this by calculate the number of vectors on init.
>
> Consider we have N queues, the number of vectors needed is 2*N + 2
> (plus one config interrupt and control vq). We didn't check whether or
> not host support control vq because it was added unconditionally by
> qemu to avoid breaking legacy guests such as Minix.
>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---

Unnecessary debug line was found, will send V2.
Michael S. Tsirkin Feb. 23, 2014, 6:34 a.m. UTC | #2
On Fri, Feb 21, 2014 at 01:00:57PM +0800, Jason Wang wrote:
> Currently, the default msix vectors for virtio-net-pci is 3 which is
> obvious not suitable for multiqueue guest, so we depends on the user
> or management tools to pass a correct vectors parameter. In fact, we
> can simplifying this by calculate the number of vectors on init.
> 
> Consider we have N queues, the number of vectors needed is 2*N + 2
> (plus one config interrupt and control vq). We didn't check whether or
> not host support control vq because it was added unconditionally by
> qemu to avoid breaking legacy guests such as Minix.
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  hw/virtio/virtio-pci.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 7b91841..1dec491 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1416,7 +1416,8 @@ static const TypeInfo virtio_serial_pci_info = {
>  static Property virtio_net_properties[] = {
>      DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
>                      VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, false),
> -    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 3),
> +    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors,
> +                       DEV_NVECTORS_UNSPECIFIED),
>      DEFINE_VIRTIO_NET_FEATURES(VirtIOPCIProxy, host_features),
>      DEFINE_NIC_PROPERTIES(VirtIONetPCI, vdev.nic_conf),
>      DEFINE_VIRTIO_NET_PROPERTIES(VirtIONetPCI, vdev.net_conf),
> @@ -1428,6 +1429,13 @@ static int virtio_net_pci_init(VirtIOPCIProxy *vpci_dev)
>      DeviceState *qdev = DEVICE(vpci_dev);
>      VirtIONetPCI *dev = VIRTIO_NET_PCI(vpci_dev);
>      DeviceState *vdev = DEVICE(&dev->vdev);
> +    VirtIONet *net = VIRTIO_NET(&dev->vdev);
> +
> +    if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
> +        vpci_dev->nvectors = 2 * MAX(net->nic_conf.queues, 1) + 2;
> +    }
> +
> +    fprintf(stderr, "vectors is %d\n", vpci_dev->nvectors);

last lin shouldn't be there obviously.

>  
>      virtio_net_set_config_size(&dev->vdev, vpci_dev->host_features);
>      virtio_net_set_netclient_name(&dev->vdev, qdev->id,
> -- 
> 1.8.3.2
Jason Wang Feb. 24, 2014, 4:58 a.m. UTC | #3
On 02/23/2014 02:34 PM, Michael S. Tsirkin wrote:
> On Fri, Feb 21, 2014 at 01:00:57PM +0800, Jason Wang wrote:
>> Currently, the default msix vectors for virtio-net-pci is 3 which is
>> obvious not suitable for multiqueue guest, so we depends on the user
>> or management tools to pass a correct vectors parameter. In fact, we
>> can simplifying this by calculate the number of vectors on init.
>>
>> Consider we have N queues, the number of vectors needed is 2*N + 2
>> (plus one config interrupt and control vq). We didn't check whether or
>> not host support control vq because it was added unconditionally by
>> qemu to avoid breaking legacy guests such as Minix.
>>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Michael S. Tsirkin <mst@redhat.com>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>  hw/virtio/virtio-pci.c | 10 +++++++++-
>>  1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
>> index 7b91841..1dec491 100644
>> --- a/hw/virtio/virtio-pci.c
>> +++ b/hw/virtio/virtio-pci.c
>> @@ -1416,7 +1416,8 @@ static const TypeInfo virtio_serial_pci_info = {
>>  static Property virtio_net_properties[] = {
>>      DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
>>                      VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, false),
>> -    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 3),
>> +    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors,
>> +                       DEV_NVECTORS_UNSPECIFIED),
>>      DEFINE_VIRTIO_NET_FEATURES(VirtIOPCIProxy, host_features),
>>      DEFINE_NIC_PROPERTIES(VirtIONetPCI, vdev.nic_conf),
>>      DEFINE_VIRTIO_NET_PROPERTIES(VirtIONetPCI, vdev.net_conf),
>> @@ -1428,6 +1429,13 @@ static int virtio_net_pci_init(VirtIOPCIProxy *vpci_dev)
>>      DeviceState *qdev = DEVICE(vpci_dev);
>>      VirtIONetPCI *dev = VIRTIO_NET_PCI(vpci_dev);
>>      DeviceState *vdev = DEVICE(&dev->vdev);
>> +    VirtIONet *net = VIRTIO_NET(&dev->vdev);
>> +
>> +    if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
>> +        vpci_dev->nvectors = 2 * MAX(net->nic_conf.queues, 1) + 2;
>> +    }
>> +
>> +    fprintf(stderr, "vectors is %d\n", vpci_dev->nvectors);
> last lin shouldn't be there obviously.

True, I've sent V2 to the list, please have a look.

Thanks
>>  
>>      virtio_net_set_config_size(&dev->vdev, vpci_dev->host_features);
>>      virtio_net_set_netclient_name(&dev->vdev, qdev->id,
>> -- 
>> 1.8.3.2
diff mbox

Patch

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 7b91841..1dec491 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1416,7 +1416,8 @@  static const TypeInfo virtio_serial_pci_info = {
 static Property virtio_net_properties[] = {
     DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
                     VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, false),
-    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 3),
+    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors,
+                       DEV_NVECTORS_UNSPECIFIED),
     DEFINE_VIRTIO_NET_FEATURES(VirtIOPCIProxy, host_features),
     DEFINE_NIC_PROPERTIES(VirtIONetPCI, vdev.nic_conf),
     DEFINE_VIRTIO_NET_PROPERTIES(VirtIONetPCI, vdev.net_conf),
@@ -1428,6 +1429,13 @@  static int virtio_net_pci_init(VirtIOPCIProxy *vpci_dev)
     DeviceState *qdev = DEVICE(vpci_dev);
     VirtIONetPCI *dev = VIRTIO_NET_PCI(vpci_dev);
     DeviceState *vdev = DEVICE(&dev->vdev);
+    VirtIONet *net = VIRTIO_NET(&dev->vdev);
+
+    if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
+        vpci_dev->nvectors = 2 * MAX(net->nic_conf.queues, 1) + 2;
+    }
+
+    fprintf(stderr, "vectors is %d\n", vpci_dev->nvectors);
 
     virtio_net_set_config_size(&dev->vdev, vpci_dev->host_features);
     virtio_net_set_netclient_name(&dev->vdev, qdev->id,