Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=2b1244a43be97f504494b557a7f7a65fe0d00dba Commit: 2b1244a43be97f504494b557a7f7a65fe0d00dba Parent: 72d0b7a81d60f5e64ee7197bc190b9b3265f99dd Author: Chris Leech <[EMAIL PROTECTED]> AuthorDate: Thu Mar 8 09:57:36 2007 -0800 Committer: Dan Williams <[EMAIL PROTECTED]> CommitDate: Wed Jul 11 16:10:53 2007 -0700
I/OAT: Only offload copies for TCP when there will be a context switch 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 <[EMAIL PROTECTED]> --- 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 450f44b..0eb7cf1 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1116,6 +1116,8 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, long timeo; struct task_struct *user_recv = NULL; int copied_early = 0; + int available = 0; + struct sk_buff *skb; lock_sock(sk); @@ -1142,7 +1144,11 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, #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); @@ -1151,7 +1157,6 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, #endif do { - struct sk_buff *skb; u32 offset; /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */ @@ -1439,7 +1444,6 @@ 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 git-commits-head" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html