Re: [libvirt] [PATCH] kvm/virtio: Set IFF_VNET_HDR when setting up tap fds

2009-01-27 Thread Daniel P. Berrange
On Mon, Jan 26, 2009 at 10:39:25AM +, Mark McLoughlin wrote: IFF_VNET_HDR is a tun/tap flag that allows you to send and receive large (i.e. GSO) packets and packets with partial checksums. Setting the flag means that every packet is proceeded by the same header which virtio uses to

Re: [libvirt] [PATCH] kvm/virtio: Set IFF_VNET_HDR when setting up tap fds

2009-01-27 Thread Mark McLoughlin
On Tue, 2009-01-27 at 10:05 +, Daniel P. Berrange wrote: On Mon, Jan 26, 2009 at 10:39:25AM +, Mark McLoughlin wrote: It's nearly five months since kvm-74 - the first KVM release with this feature - was released. Up until now, we've not added libvirt support because there is no

[libvirt] [PATCH] kvm/virtio: Set IFF_VNET_HDR when setting up tap fds

2009-01-26 Thread Mark McLoughlin
IFF_VNET_HDR is a tun/tap flag that allows you to send and receive large (i.e. GSO) packets and packets with partial checksums. Setting the flag means that every packet is proceeded by the same header which virtio uses to communicate GSO/csum metadata. By enabling this flag on the tap fds we

Re: [libvirt] [PATCH] kvm/virtio: Set IFF_VNET_HDR when setting up tap fds

2009-01-26 Thread Richard W.M. Jones
On Mon, Jan 26, 2009 at 10:39:25AM +, Mark McLoughlin wrote: IFF_VNET_HDR is a tun/tap flag that allows you to send and receive large (i.e. GSO) packets and packets with partial checksums. Setting the flag means that every packet is proceeded by the same header which virtio uses to

Re: [libvirt] [PATCH] kvm/virtio: Set IFF_VNET_HDR when setting up tap fds

2009-01-26 Thread Mark McLoughlin
Hi Rich, On Mon, 2009-01-26 at 11:39 +, Richard W.M. Jones wrote: On Mon, Jan 26, 2009 at 10:39:25AM +, Mark McLoughlin wrote: IFF_VNET_HDR is a tun/tap flag that allows you to send and receive large (i.e. GSO) packets and packets with partial checksums. Setting the flag means that

[libvirt] [PATCH] kvm/virtio: Set IFF_VNET_HDR when setting up tap fds

2008-08-13 Thread Mark McLoughlin
Hey, Here's a patch that allows libvirt created guests to use KVM's recent GSO support in order to increase the throughput achieved with virtio_net network interfaces. We shouldn't apply this yet - we need the kernel and kvm TUNGETIFF patches to be applied first - so this is just intended as an

Re: [libvirt] [PATCH] kvm/virtio: Set IFF_VNET_HDR when setting up tap fds

2008-08-13 Thread Daniel P. Berrange
On Wed, Aug 13, 2008 at 03:53:27PM +0100, Mark McLoughlin wrote: By enabling this flag on the tap fds we create, we greatly increase the achievable throughput with virtio_net. However, we need to be careful to only set the flag when a) KVM has support for this ABI and b) the value of the

Re: [libvirt] [PATCH] kvm/virtio: Set IFF_VNET_HDR when setting up tap fds

2008-08-13 Thread Mark McLoughlin
On Wed, 2008-08-13 at 16:01 +0100, Daniel P. Berrange wrote: On Wed, Aug 13, 2008 at 03:53:27PM +0100, Mark McLoughlin wrote: By enabling this flag on the tap fds we create, we greatly increase the achievable throughput with virtio_net. However, we need to be careful to only set the flag

Re: [libvirt] [PATCH] kvm/virtio: Set IFF_VNET_HDR when setting up tap fds

2008-08-13 Thread Mark McLoughlin
On Wed, 2008-08-13 at 15:53 +0100, Mark McLoughlin wrote: +net-model !strcmp(net-model, virtio)) Should be: +net-model STREQ(net-model, virtio)) Cheers, Mark. -- Libvir-list mailing list Libvir-list@redhat.com

Re: [libvirt] [PATCH] kvm/virtio: Set IFF_VNET_HDR when setting up tap fds

2008-08-13 Thread Daniel P. Berrange
On Wed, Aug 13, 2008 at 04:14:10PM +0100, Mark McLoughlin wrote: On Wed, 2008-08-13 at 16:01 +0100, Daniel P. Berrange wrote: On Wed, Aug 13, 2008 at 03:53:27PM +0100, Mark McLoughlin wrote: By enabling this flag on the tap fds we create, we greatly increase the achievable throughput with