Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750770AbWHPArO (ORCPT ); Tue, 15 Aug 2006 20:47:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750755AbWHPApz (ORCPT ); Tue, 15 Aug 2006 20:45:55 -0400 Received: from [63.64.152.142] ([63.64.152.142]:32265 "EHLO gitlost.site") by vger.kernel.org with ESMTP id S1750751AbWHPApw (ORCPT ); Tue, 15 Aug 2006 20:45:52 -0400 From: Chris Leech Subject: [PATCH 2/7] [I/OAT] Only offload copies for TCP when there will be a context switch Date: Tue, 15 Aug 2006 17:53:39 -0700 To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Message-Id: <20060816005339.8634.23929.stgit@gitlost.site> In-Reply-To: <20060816005337.8634.70033.stgit@gitlost.site> References: <20060816005337.8634.70033.stgit@gitlost.site> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1895 Lines: 58 The performance wins come with having the DMA copy engine doing the copies in parallel with the context switch. If there is enough data ready on the socket at recv time just use a regular copy. Signed-off-by: Chris Leech --- net/ipv4/tcp.c | 10 +++++++--- 1 files changed, 7 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 934396b..36f6b64 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1105,6 +1105,8 @@ int tcp_recvmsg(struct kiocb *iocb, stru long timeo; struct task_struct *user_recv = NULL; int copied_early = 0; + int available = 0; + struct sk_buff *skb; lock_sock(sk); @@ -1131,7 +1133,11 @@ int tcp_recvmsg(struct kiocb *iocb, stru #ifdef CONFIG_NET_DMA tp->ucopy.dma_chan = NULL; preempt_disable(); - if ((len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) && + skb = skb_peek_tail(&sk->sk_receive_queue); + if (skb) + available = TCP_SKB_CB(skb)->seq + skb->len - (*seq); + if ((available < target) && + (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) && !sysctl_tcp_low_latency && __get_cpu_var(softnet_data).net_dma) { preempt_enable_no_resched(); tp->ucopy.pinned_list = dma_pin_iovec_pages(msg->msg_iov, len); @@ -1140,7 +1146,6 @@ int tcp_recvmsg(struct kiocb *iocb, stru #endif do { - struct sk_buff *skb; u32 offset; /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */ @@ -1428,7 +1433,6 @@ skip_copy: #ifdef CONFIG_NET_DMA if (tp->ucopy.dma_chan) { - struct sk_buff *skb; dma_cookie_t done, used; dma_async_memcpy_issue_pending(tp->ucopy.dma_chan); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/