Commit b4e26f5e authored Jul 05, 2005 by David S. Miller

[TCP]: Fix send-side cpu utiliziation regression.



Only put user data purely to pages when doing TSO.

The extra page allocations cause two problems:

1) Add the overhead of the page allocations themselves.
2) Make us do small user copies when we get to the end
   of the TCP socket cache page.

It is still beneficial to purely use pages for TSO,
so we will do it for that case.

Signed-off-by: David S. Miller <davem@davemloft.net>

parent aa93466b

net/ipv4/tcp.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -756,8 +756,17 @@ static inline int select_size(struct sock sk, struct tcp_sock tp)
		{
		int tmp = tp->mss_cache_std;

		if (sk->sk_route_caps & NETIF_F_SG)
		if (sk->sk_route_caps & NETIF_F_SG) {
		if (sk->sk_route_caps & NETIF_F_TSO)
		tmp = 0;
		else {
		int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);

		if (tmp >= pgbreak &&
		tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
		tmp = pgbreak;
		}
		}

		return tmp;
		}