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authorChris Leech <christopher.leech@intel.com>2007-03-08 09:57:36 -0800
committerDan Williams <dan.j.williams@intel.com>2007-07-11 16:10:53 -0700
commit2b1244a43be97f504494b557a7f7a65fe0d00dba (patch)
treed3be36597917dbbae664fc6eb97dbe876c5e44e3
parent72d0b7a81d60f5e64ee7197bc190b9b3265f99dd (diff)
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 <christopher.leech@intel.com>
-rw-r--r--net/ipv4/tcp.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 450f44bb2c8..0eb7cf1002c 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);