Commit 70957eae authored May 11, 2017 by Vlad Yasevich Committed by David S. Miller May 15, 2017

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>

parent 66c25f6e

drivers/net/macvlan.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -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;

Admin message