[PATCH 3/7] [I/OAT] Don't offload copies for loopback traffic
From: Chris Leech <hidden>
Date: 2006-08-16 00:45:59
Also in:
lkml
Subsystem:
networking [general], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
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 <redacted> --- 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();