similar to: [PATCH net] virtio-net: keep vnet header zeroed after processing XDP

On Mon, Oct 28, 2013 at 10:44 PM, Michael Dalton <mwdalton at google.com> wrote: > The virtio_net driver's mergeable receive buffer allocator > uses 4KB packet buffers. For MTU-sized traffic, SKB truesize > is > 4KB but only ~1500 bytes of the buffer is used to store > packet data, reducing the effective TCP window size > substantially. This patch addresses the

We don't disable VIRTIO_NET_F_GUEST_CSUM if XDP was set. This means we can receive partial csumed packets with metadata kept in the vnet_hdr. This may have several side effects: - It could be overridden by header adjustment, thus is might be not correct after XDP processing. - There's no way to pass such metadata information through XDP_REDIRECT to another driver. - XDP does not

The virtio_net driver's mergeable receive buffer allocator uses 4KB packet buffers. For MTU-sized traffic, SKB truesize is > 4KB but only ~1500 bytes of the buffer is used to store packet data, reducing the effective TCP window size substantially. This patch addresses the performance concerns with mergeable receive buffers by allocating MTU-sized packet buffers using page frag allocators.

We don't disable VIRTIO_NET_F_GUEST_CSUM if XDP was set. This means we can receive partial csumed packets with metadata kept in the vnet_hdr. This may have several side effects: - It could be overridden by header adjustment, thus is might be not correct after XDP processing. - There's no way to pass such metadata information through XDP_REDIRECT to another driver. - XDP does not

The virtio_net driver's mergeable receive buffer allocator uses 4KB packet buffers. For MTU-sized traffic, SKB truesize is > 4KB but only ~1500 bytes of the buffer is used to store packet data, reducing the effective TCP window size substantially. This patch addresses the performance concerns with mergeable receive buffers by allocating MTU-sized packet buffers using page frag allocators.

Too many places poke at [rs]q->vq->vdev->priv just to get the the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+), 18 deletions(-) diff --git a/drivers/net/virtio_net.c

Too many places poke at [rs]q->vq->vdev->priv just to get the the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+), 18 deletions(-) diff --git a/drivers/net/virtio_net.c

Too many places poke at [rs]q->vq->vdev->priv just to get the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck at de.ibm.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+),

Too many places poke at [rs]q->vq->vdev->priv just to get the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck at de.ibm.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+),

Too many places poke at [rs]q->vq->vdev->priv just to get the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck at de.ibm.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+),

Too many places poke at [rs]q->vq->vdev->priv just to get the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck at de.ibm.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+),

Too many places poke at [rs]q->vq->vdev->priv just to get the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck at de.ibm.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+),

Too many places poke at [rs]q->vq->vdev->priv just to get the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck at de.ibm.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+),

Too many places poke at [rs]q->vq->vdev->priv just to get the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck at de.ibm.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+),

Too many places poke at [rs]q->vq->vdev->priv just to get the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck at de.ibm.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+),

Too many places poke at [rs]q->vq->vdev->priv just to get the the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+), 18 deletions(-) diff --git a/drivers/net/virtio_net.c

Too many places poke at [rs]q->vq->vdev->priv just to get the the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/net/virtio_net.c | 38 ++++++++++++++++++++------------------ 1 file changed, 20 insertions(+), 18 deletions(-) diff --git a/drivers/net/virtio_net.c

Too many places poke at [rs]q->vq->vdev->priv just to get the the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/net/virtio_net.c | 36 +++++++++++++++++++----------------- 1 file changed, 19 insertions(+), 17 deletions(-) diff --git a/drivers/net/virtio_net.c

Too many places poke at [rs]q->vq->vdev->priv just to get the the vi structure. Let's just pass the pointer around: seems cleaner, and might even be faster. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/net/virtio_net.c | 36 +++++++++++++++++++----------------- 1 file changed, 19 insertions(+), 17 deletions(-) diff --git a/drivers/net/virtio_net.c

Commit f600b6905015 ("virtio_net: Add XDP support") leaves the case of small receive buffer untouched. This will confuse the user who want to set XDP but use small buffers. Other than forbid XDP in small buffer mode, let's make it work. XDP then can only work at skb->data since virtio-net create skbs during refill, this is sub optimal which could be optimized in the future. Cc: