On 07/29/2012 11:44 AM, Michael S. Tsirkin wrote: > On Sat, Jul 21, 2012 at 02:02:58PM +0200, Sasha Levin wrote: >> On 07/20/2012 03:40 PM, Michael S. Tsirkin wrote: >>>> - err = init_vqs(vi); >>>>> + if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) >>>>> + vi->has_cvq = true; >>>>> + >>> How about we disable multiqueue if there's no cvq? >>> Will make logic a bit simpler, won't it? >> >> multiqueues don't really depend on cvq. Does this added complexity really >> justifies adding an artificial limit? > > Well !cvq support is a legacy feature: the reason we support it > in driver is to avoid breaking on old hosts. Adding more code to that > path just doesn't make much sense since old hosts won't have mq.
Is it really a legacy feature? The spec suggests that its an optional queue which is not necessary for the operation of the device. Which is why we never implemented it in lkvm - we weren't interested in any of the features it provided at that time and we could provide high performance with vhost support even without it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
