From: "Michael S. Tsirkin" <mst@xxxxxxxxxx> Date: Mon, 18 Jul 2011 16:48:46 +0300 >>From: Shirley Ma <mashirle@xxxxxxxxxx> > > This adds experimental zero copy support in vhost-net, > disabled by default. To enable, set > experimental_zcopytx module option to 1. > > This patch maintains the outstanding userspace buffers in the > sequence it is delivered to vhost. The outstanding userspace buffers > will be marked as done once the lower device buffers DMA has finished. > This is monitored through last reference of kfree_skb callback. Two > buffer indices are used for this purpose. > > The vhost-net device passes the userspace buffers info to lower device > skb through message control. DMA done status check and guest > notification are handled by handle_tx: in the worst case is all buffers > in the vq are in pending/done status, so we need to notify guest to > release DMA done buffers first before we get any new buffers from the > vq. > > One known problem is that if the guest stops submitting > buffers, buffers might never get used until some > further action, e.g. device reset. This does not > seem to affect linux guests. > > Signed-off-by: Shirley <xma@xxxxxxxxxx> > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Applied, thanks! -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
