From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Leech Subject: [PATCH 3/7] [I/OAT] Don't offload copies for loopback traffic Date: Tue, 15 Aug 2006 17:53:41 -0700 Message-ID: <20060816005341.8634.10380.stgit@gitlost.site> References: <20060816005337.8634.70033.stgit@gitlost.site> Return-path: Received: from [63.64.152.142] ([63.64.152.142]:33289 "EHLO gitlost.site") by vger.kernel.org with ESMTP id S1750756AbWHPApz (ORCPT ); Tue, 15 Aug 2006 20:45:55 -0400 To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org In-Reply-To: <20060816005337.8634.70033.stgit@gitlost.site> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Local traffic (loopback) is generally in cache anyway, and the overhead cost of offloading the copy is worse than just doing it with the CPU. Signed-off-by: Chris Leech --- net/ipv4/tcp.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 36f6b64..7971e73 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1107,6 +1107,7 @@ int tcp_recvmsg(struct kiocb *iocb, stru int copied_early = 0; int available = 0; struct sk_buff *skb; + struct dst_entry *dst; lock_sock(sk); @@ -1136,7 +1137,8 @@ int tcp_recvmsg(struct kiocb *iocb, stru skb = skb_peek_tail(&sk->sk_receive_queue); if (skb) available = TCP_SKB_CB(skb)->seq + skb->len - (*seq); - if ((available < target) && + dst = __sk_dst_get(sk); + if ((available < target) && (!dst || (dst->dev != &loopback_dev)) && (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) && !sysctl_tcp_low_latency && __get_cpu_var(softnet_data).net_dma) { preempt_enable_no_resched();