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authorAlexey Kuznetsov <kuznet@ms2.inr.ac.ru>2006-09-19 12:52:50 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2006-09-22 15:19:05 -0700
commit1ef9696c909060ccdae3ade245ca88692b49285b (patch)
tree3a2df5bbd6b448a4f873125ab5dd7c7a0cc7ae05 /net/ipv4/tcp.c
parent4eb327b517cf85f6cb7dcd5691e7b748cbe8c343 (diff)
[TCP]: Send ACKs each 2nd received segment.
It does not affect either mss-sized connections (obviously) or connections controlled by Nagle (because there is only one small segment in flight). The idea is to record the fact that a small segment arrives on a connection, where one small segment has already been received and still not-ACKed. In this case ACK is forced after tcp_recvmsg() drains receive buffer. In other words, it is a "soft" each-2nd-segment ACK, which is enough to preserve ACK clock even when ABC is enabled. Signed-off-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp.c')
-rw-r--r--net/ipv4/tcp.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 29e3d606db7..66e9a729f6d 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -955,8 +955,11 @@ void tcp_cleanup_rbuf(struct sock *sk, int copied)
* receive buffer and there was a small segment
* in queue.
*/
- (copied > 0 && (icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
- !icsk->icsk_ack.pingpong && !atomic_read(&sk->sk_rmem_alloc)))
+ (copied > 0 &&
+ ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
+ ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
+ !icsk->icsk_ack.pingpong)) &&
+ !atomic_read(&sk->sk_rmem_alloc)))
time_to_ack = 1;
}