From 3d5b06051cd5fa82c9a4285f7ce8650a0f0845ff Mon Sep 17 00:00:00 2001 From: Ed Cashin Date: Thu, 4 Oct 2012 17:16:20 -0700 Subject: aoe: for performance support larger packet payloads tAdd adds the ability to work with large packets composed of a number of segments, using the scatter gather feature of the block layer (biovecs) and the network layer (skb frag array). The motivation is the performance gained by using a packet data payload greater than a page size and by using the network card's scatter gather feature. Users of the out-of-tree aoe driver already had these changes, but since early 2011, they have complained of increased memory utilization and higher CPU utilization during heavy writes.[1] The commit below appears related, as it disables scatter gather on non-IP protocols inside the harmonize_features function, even when the NIC supports sg. commit f01a5236bd4b140198fbcc550f085e8361fd73fa Author: Jesse Gross Date: Sun Jan 9 06:23:31 2011 +0000 net offloading: Generalize netif_get_vlan_features(). With that regression in place, transmits always linearize sg AoE packets, but in-kernel users did not have this patch. Before 2.6.38, though, these changes were working to allow sg to increase performance. 1. http://www.spinics.net/lists/linux-mm/msg15184.html Signed-off-by: Ed Cashin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/aoe/aoenet.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'drivers/block/aoe/aoenet.c') diff --git a/drivers/block/aoe/aoenet.c b/drivers/block/aoe/aoenet.c index 4d3bc0d49df5..07878076e43c 100644 --- a/drivers/block/aoe/aoenet.c +++ b/drivers/block/aoe/aoenet.c @@ -102,7 +102,9 @@ static int aoenet_rcv(struct sk_buff *skb, struct net_device *ifp, struct packet_type *pt, struct net_device *orig_dev) { struct aoe_hdr *h; + struct aoe_atahdr *ah; u32 n; + int sn; if (dev_net(ifp) != &init_net) goto exit; @@ -110,13 +112,16 @@ aoenet_rcv(struct sk_buff *skb, struct net_device *ifp, struct packet_type *pt, skb = skb_share_check(skb, GFP_ATOMIC); if (skb == NULL) return 0; - if (skb_linearize(skb)) - goto exit; if (!is_aoe_netif(ifp)) goto exit; skb_push(skb, ETH_HLEN); /* (1) */ - - h = (struct aoe_hdr *) skb_mac_header(skb); + sn = sizeof(*h) + sizeof(*ah); + if (skb->len >= sn) { + sn -= skb_headlen(skb); + if (sn > 0 && !__pskb_pull_tail(skb, sn)) + goto exit; + } + h = (struct aoe_hdr *) skb->data; n = get_unaligned_be32(&h->tag); if ((h->verfl & AOEFL_RSP) == 0 || (n & 1<<31)) goto exit; -- cgit v1.2.3-55-g7522