net: introduce netdevice gso_min_segs attribute
Some TSO engines might have a too heavy setup cost, that impacts
performance on hosts sending small bursts (2 MSS per packet).
This patch adds a device gso_min_segs, allowing drivers to set
a minimum segment size for TSO packets, according to the NIC
performance.
Tested on a mlx4 NIC, this allows to get a ~110% increase of
throughput when sending 2 MSS per packet.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 22d54b9..2df86f5 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1416,6 +1416,8 @@
* @gso_max_size: Maximum size of generic segmentation offload
* @gso_max_segs: Maximum number of segments that can be passed to the
* NIC for GSO
+ * @gso_min_segs: Minimum number of segments that can be passed to the
+ * NIC for GSO
*
* @dcbnl_ops: Data Center Bridging netlink ops
* @num_tc: Number of traffic classes in the net device
@@ -1666,7 +1668,7 @@
unsigned int gso_max_size;
#define GSO_MAX_SEGS 65535
u16 gso_max_segs;
-
+ u16 gso_min_segs;
#ifdef CONFIG_DCB
const struct dcbnl_rtnl_ops *dcbnl_ops;
#endif
diff --git a/net/core/dev.c b/net/core/dev.c
index 7d5691c..c1a4de2 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2567,10 +2567,12 @@
netdev_features_t netif_skb_features(struct sk_buff *skb)
{
+ const struct net_device *dev = skb->dev;
+ netdev_features_t features = dev->features;
+ u16 gso_segs = skb_shinfo(skb)->gso_segs;
__be16 protocol = skb->protocol;
- netdev_features_t features = skb->dev->features;
- if (skb_shinfo(skb)->gso_segs > skb->dev->gso_max_segs)
+ if (gso_segs > dev->gso_max_segs || gso_segs < dev->gso_min_segs)
features &= ~NETIF_F_GSO_MASK;
if (protocol == htons(ETH_P_8021Q) || protocol == htons(ETH_P_8021AD)) {
@@ -2581,7 +2583,7 @@
}
features = netdev_intersect_features(features,
- skb->dev->vlan_features |
+ dev->vlan_features |
NETIF_F_HW_VLAN_CTAG_TX |
NETIF_F_HW_VLAN_STAG_TX);
@@ -6661,6 +6663,7 @@
dev->gso_max_size = GSO_MAX_SIZE;
dev->gso_max_segs = GSO_MAX_SEGS;
+ dev->gso_min_segs = 0;
INIT_LIST_HEAD(&dev->napi_list);
INIT_LIST_HEAD(&dev->unreg_list);