[PATCH v2] tcp: cwnd does not increase in TCP YeAH

2016-09-07 Thread Artem Germanov 
Commit 76174004a0f19785a328f40388e87e982bbf69b9
(tcp: do not slow start when cwnd equals ssthresh )
introduced regression in TCP YeAH. Using 100ms delay 1% loss virtual 
ethernet link kernel 4.2 shows bandwidth ~500KB/s for single TCP 
connection and kernel 4.3 and above (including 4.8-rc4) shows bandwidth 
~100KB/s.
   That is caused by stalled cwnd when cwnd equals ssthresh. This patch 
fixes it by proper increasing cwnd in this case.

Signed-off-by: Artem Germanov <agerma...@anchorfree.com>
Acked-by: Dmitry Adamushko <d.adamus...@anchorfree.com>
---
diff --git a/net/ipv4/tcp_yeah.c b/net/ipv4/tcp_yeah.c
index 028eb04..9c5fc97 100644
--- a/net/ipv4/tcp_yeah.c
+++ b/net/ipv4/tcp_yeah.c
@@ -76,7 +76,7 @@ static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack, u32 
acked)
if (!tcp_is_cwnd_limited(sk))
return;
 
-   if (tp->snd_cwnd <= tp->snd_ssthresh)
+   if (tcp_in_slow_start(tp))
tcp_slow_start(tp, acked);
 
else if (!yeah->doing_reno_now) {

[PATCH] tcp: cwnd does not increase in TCP YeAH

2016-09-04 Thread Artem Germanov 

Commit 76174004a0f19785a328f40388e87e982bbf69b9
(tcp: do not slow start when cwnd equals ssthresh )
introduced regression in TCP YeAH. Using 100ms delay 1% loss virtual 
ethernet link kernel 4.2 shows bandwidth ~500KB/s for single TCP 
connection and kernel 4.3 and above (including 4.8-rc4) shows bandwidth 
~100KB/s.
 That is caused by stalled cwnd when cwnd equals ssthresh. This patch 
fixes it by proper increasing cwnd in this case.


Signed-off-by: Artem Germanov <agerma...@anchorfree.com>
---
--- net/ipv4/tcp_yeah.c.orig2016-09-04 09:53:01.0 -0700
+++ net/ipv4/tcp_yeah.c 2016-09-04 09:53:40.0 -0700
@@ -76,7 +76,7 @@ static void tcp_yeah_cong_avoid(struct s
if (!tcp_is_cwnd_limited(sk))
return;

-   if (tp->snd_cwnd <= tp->snd_ssthresh)
+   if (tcp_in_slow_start(tp))
tcp_slow_start(tp, acked);

else if (!yeah->doing_reno_now) {