diff options
| author | Florian Westphal <fw@strlen.de> | 2017-08-30 19:24:58 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-08-30 11:20:09 -0700 |
| commit | 31770e34e43d6c8dee129bfee77e56c34e61f0e5 (patch) | |
| tree | a4635a632732b39ef560a8f72eb3a81d04f01605 /net/ipv4/tcp.c | |
| parent | c1d2b4c3e204e602c97680335d082b8d012d08cd (diff) | |
tcp: Revert "tcp: remove header prediction"
This reverts commit 45f119bf936b1f9f546a0b139c5b56f9bb2bdc78.
Eric Dumazet says:
We found at Google a significant regression caused by
45f119bf936b1f9f546a0b139c5b56f9bb2bdc78 tcp: remove header prediction
In typical RPC (TCP_RR), when a TCP socket receives data, we now call
tcp_ack() while we used to not call it.
This touches enough cache lines to cause a slowdown.
so problem does not seem to be HP removal itself but the tcp_ack()
call. Therefore, it might be possible to remove HP after all, provided
one finds a way to elide tcp_ack for most cases.
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp.c')
| -rw-r--r-- | 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 566083ee2654..21ca2df274c5 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1963,8 +1963,10 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, tcp_rcv_space_adjust(sk); skip_copy: - if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) + if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) { tp->urg_data = 0; + tcp_fast_path_check(sk); + } if (used + offset < skb->len) continue; |