From: Ilpo J�rvinen <[email protected]>
commit 49ff4bb4cd4c04acf8f9e3d3ec2148305a1db445 in mainline.
[TCP]: DSACK signals data receival, be conservative
In case a DSACK is received, it's better to lower cwnd as it's
a sign of data receival.
Signed-off-by: Ilpo J�rvinen <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
net/ipv4/tcp_input.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -103,6 +103,7 @@ int sysctl_tcp_abc __read_mostly;
#define FLAG_SLOWPATH 0x100 /* Do not skip RFC checks for window update.*/
#define FLAG_ONLY_ORIG_SACKED 0x200 /* SACKs only non-rexmit sent before RTO */
#define FLAG_SND_UNA_ADVANCED 0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */
+#define FLAG_DSACKING_ACK 0x800 /* SACK blocks contained DSACK info */
#define FLAG_ACKED (FLAG_DATA_ACKED|FLAG_SYN_ACKED)
#define FLAG_NOT_DUP (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED)
@@ -966,12 +967,14 @@ tcp_sacktag_write_queue(struct sock *sk,
/* Check for D-SACK. */
if (before(ntohl(sp[0].start_seq), TCP_SKB_CB(ack_skb)->ack_seq)) {
+ flag |= FLAG_DSACKING_ACK;
found_dup_sack = 1;
tp->rx_opt.sack_ok |= 4;
NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV);
} else if (num_sacks > 1 &&
!after(ntohl(sp[0].end_seq), ntohl(sp[1].end_seq)) &&
!before(ntohl(sp[0].start_seq), ntohl(sp[1].start_seq))) {
+ flag |= FLAG_DSACKING_ACK;
found_dup_sack = 1;
tp->rx_opt.sack_ok |= 4;
NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV);
@@ -1858,7 +1861,7 @@ static void tcp_cwnd_down(struct sock *s
struct tcp_sock *tp = tcp_sk(sk);
int decr = tp->snd_cwnd_cnt + 1;
- if ((flag&FLAG_ANY_PROGRESS) ||
+ if ((flag&(FLAG_ANY_PROGRESS|FLAG_DSACKING_ACK)) ||
(IsReno(tp) && !(flag&FLAG_NOT_DUP))) {
tp->snd_cwnd_cnt = decr&1;
decr >>= 1;
--
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
