macvlan: Fix performance issues with vlan tagged packets

Macvlan always turns on offload features that have sofware
fallback (NETIF_GSO_SOFTWARE).  This allows much higher guest-guest
communications over macvtap.

However, macvtap does not turn on these features for vlan tagged traffic.
As a result, depending on the HW that mactap is configured on, the
performance of guest-guest communication over a vlan is very
inconsistent.  If the HW supports TSO/UFO over vlans, then the
performance will be fine.  If not, the the performance will suffer
greatly since the VM may continue using TSO/UFO, and will force the host
segment the traffic and possibly overlow the macvtap queue.

This patch adds the always on offloads to vlan_features.  This
makes sure that any vlan tagged traffic between 2 guest will not
be segmented needlessly.

Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index b34eaaae03fd..346ad2ff3998 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -789,10 +789,12 @@ static int macvlan_change_mtu(struct net_device *dev, int new_mtu)
  */
 static struct lock_class_key macvlan_netdev_addr_lock_key;
 
-#define ALWAYS_ON_FEATURES \
-        (NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_GSO_SOFTWARE | NETIF_F_LLTX | \
+#define ALWAYS_ON_OFFLOADS \
+        (NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_GSO_SOFTWARE | \
          NETIF_F_GSO_ROBUST)
 
+#define ALWAYS_ON_FEATURES (ALWAYS_ON_OFFLOADS | NETIF_F_LLTX)
+
 #define MACVLAN_FEATURES \
         (NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_FRAGLIST | \
          NETIF_F_GSO | NETIF_F_TSO | NETIF_F_UFO | NETIF_F_LRO | \
@@ -827,6 +829,7 @@ static int macvlan_init(struct net_device *dev)
         dev->features           |= ALWAYS_ON_FEATURES;
         dev->hw_features        |= NETIF_F_LRO;
         dev->vlan_features      = lowerdev->vlan_features & MACVLAN_FEATURES;
+        dev->vlan_features      |= ALWAYS_ON_OFFLOADS;
         dev->gso_max_size       = lowerdev->gso_max_size;
         dev->gso_max_segs       = lowerdev->gso_max_segs;
         dev->hard_header_len    = lowerdev->hard_header_len;