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net: introduce netdevice gso_min_segs attribute

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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>
This commit is contained in:
Eric Dumazet 2014-10-05 10:11:27 -07:00 committed by David S. Miller
parent 9d31a7b9f9
commit fcbeb976d7
2 changed files with 9 additions and 4 deletions
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4
include/linux/netdevice.h
View File

@ -1416,6 +1416,8 @@ enum netdev_priv_flags {
* @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 @@ struct net_device {
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

9
net/core/dev.c
View File

@ -2567,10 +2567,12 @@ static netdev_features_t harmonize_features(struct sk_buff *skb,
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 @@ netdev_features_t netif_skb_features(struct sk_buff *skb)
}
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 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
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);