From mboxrd@z Thu Jan 1 00:00:00 1970 From: Herbert Xu Subject: [PATCH 8/14] gro: Optimise length comparison in skb_gro_header Date: Wed, 27 May 2009 14:50:27 +1000 Message-ID: References: <20090527044539.GA32372@gondor.apana.org.au> To: "David S. Miller" , netdev@vger.kernel.org Return-path: Received: from rhun.apana.org.au ([64.62.148.172]:37539 "EHLO arnor.apana.org.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752770AbZE0Eub (ORCPT ); Wed, 27 May 2009 00:50:31 -0400 Sender: netdev-owner@vger.kernel.org List-ID: gro: Optimise length comparison in skb_gro_header By caching frag0_len, we can avoid checking both frag0 and the length separately in skb_gro_header. This helps as skb_gro_header is called four times per packet which amounts to a few million times at 10Gb/s. Signed-off-by: Herbert Xu --- include/linux/netdevice.h | 7 +++++-- net/core/dev.c | 5 ++++- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 38678bc..966c413 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1011,6 +1011,9 @@ struct napi_gro_cb { /* Virtual address of skb_shinfo(skb)->frags[0].page + offset. */ void *frag0; + /* Length of frag0. */ + unsigned int frag0_len; + /* This indicates where we are processing relative to skb->data. */ int data_offset; @@ -1134,9 +1137,9 @@ static inline void *skb_gro_header(struct sk_buff *skb, unsigned int hlen) unsigned int offset = skb_gro_offset(skb); hlen += offset; - if (!NAPI_GRO_CB(skb)->frag0 || - unlikely(skb_shinfo(skb)->frags[0].size < hlen)) { + if (NAPI_GRO_CB(skb)->frag0_len < hlen) { NAPI_GRO_CB(skb)->frag0 = NULL; + NAPI_GRO_CB(skb)->frag0_len = 0; return pskb_may_pull(skb, hlen) ? skb->data + offset : NULL; } diff --git a/net/core/dev.c b/net/core/dev.c index 07ad237..e634c8a 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2506,12 +2506,15 @@ void skb_gro_reset_offset(struct sk_buff *skb) { NAPI_GRO_CB(skb)->data_offset = 0; NAPI_GRO_CB(skb)->frag0 = NULL; + NAPI_GRO_CB(skb)->frag0_len = 0; if (skb->mac_header == skb->tail && - !PageHighMem(skb_shinfo(skb)->frags[0].page)) + !PageHighMem(skb_shinfo(skb)->frags[0].page)) { NAPI_GRO_CB(skb)->frag0 = page_address(skb_shinfo(skb)->frags[0].page) + skb_shinfo(skb)->frags[0].page_offset; + NAPI_GRO_CB(skb)->frag0_len = skb_shinfo(skb)->frags[0].size; + } } EXPORT_SYMBOL(skb_gro_reset_offset);