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);
-
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