tcp: don't backtrack to sacked skbs

Backtracking to sacked skbs is a horrible performance killer
since the hint cannot be advanced successfully past them...
...And it's totally unnecessary too.

In theory this is 2.6.27..28 regression but I doubt anybody
can make .28 to have worse performance because of other TCP
improvements.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index f6f61b3..2471cd4 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2065,7 +2065,7 @@ begin_fwd:
                        goto begin_fwd;
 
                } else if (!(sacked & TCPCB_LOST)) {
-                       if (hole == NULL && !(sacked & TCPCB_SACKED_RETRANS))
+                       if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED)))
                                hole = skb;
                        continue;