Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list

On Mon, Oct 26, 2015 at 11:15:57AM +0800, Jason Wang wrote:

On 10/23/2015 09:37 PM, Michael S. Tsirkin wrote:

quoted

On Fri, Oct 23, 2015 at 12:57:05AM -0400, Jason Wang wrote:

quoted

We don't have fraglist support in TAP_FEATURES. This will lead
software segmentation of gro skb with frag list. Fixes by having
frag list support in TAP_FEATURES.

With this patch single session of netperf receiving were restored from
about 5Gb/s to about 12Gb/s on mlx4.

Fixes a567dd6252 ("macvtap: simplify usage of tap_features")
Cc: Vlad Yasevich <redacted>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <redacted>

Thanks!
Does this mean we should look at re-adding NETIF_F_FRAGLIST
to virtio-net as well?

Not sure I get the point, but probably not. This is for receiving and
skb_copy_datagram_iter() can deal with frag list.

Point is:
- bridge within guest
- assigned device creating gro skbs with frag list bridged to virtio

quoted

quoted

---
 drivers/net/macvtap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 248478c..197c939 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c

@@ -137,7 +137,7 @@ static const struct proto_ops macvtap_socket_ops;
 #define TUN_OFFLOADS (NETIF_F_HW_CSUM | NETIF_F_TSO_ECN | NETIF_F_TSO | \
 		      NETIF_F_TSO6 | NETIF_F_UFO)
 #define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO)
-#define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG)
+#define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG | NETIF_F_FRAGLIST)
 
 static struct macvlan_dev *macvtap_get_vlan_rcu(const struct net_device *dev)
 {

-- 
1.8.3.1

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