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authorPengcheng Yang <yangpc@wangsu.com>2020-03-16 14:35:08 +0800
committerDavid S. Miller <davem@davemloft.net>2020-03-16 18:26:54 -0700
commit5415e3c37a657f7b400ece28e73a6f6c6cc371c4 (patch)
treef1ba3fe5fede1b2ead7306607cc7240d60ab6be7 /net
parenttcp: fix stretch ACK bugs in BIC (diff)
downloadlinux-dev-5415e3c37a657f7b400ece28e73a6f6c6cc371c4.tar.xz
linux-dev-5415e3c37a657f7b400ece28e73a6f6c6cc371c4.zip
tcp: fix stretch ACK bugs in Scalable
Change Scalable to properly handle stretch ACKs in additive increase mode by passing in the count of ACKed packets to tcp_cong_avoid_ai(). In addition, because we are now precisely accounting for stretch ACKs, including delayed ACKs, we can now change TCP_SCALABLE_AI_CNT to 100. Signed-off-by: Pengcheng Yang <yangpc@wangsu.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_scalable.c17
1 files changed, 9 insertions, 8 deletions
diff --git a/net/ipv4/tcp_scalable.c b/net/ipv4/tcp_scalable.c
index 471571e1ab26..6cebf412d590 100644
--- a/net/ipv4/tcp_scalable.c
+++ b/net/ipv4/tcp_scalable.c
@@ -10,10 +10,9 @@
#include <net/tcp.h>
/* These factors derived from the recommended values in the aer:
- * .01 and and 7/8. We use 50 instead of 100 to account for
- * delayed ack.
+ * .01 and and 7/8.
*/
-#define TCP_SCALABLE_AI_CNT 50U
+#define TCP_SCALABLE_AI_CNT 100U
#define TCP_SCALABLE_MD_SCALE 3
static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked)
@@ -23,11 +22,13 @@ static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked)
if (!tcp_is_cwnd_limited(sk))
return;
- if (tcp_in_slow_start(tp))
- tcp_slow_start(tp, acked);
- else
- tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT),
- 1);
+ if (tcp_in_slow_start(tp)) {
+ acked = tcp_slow_start(tp, acked);
+ if (!acked)
+ return;
+ }
+ tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT),
+ acked);
}
static u32 tcp_scalable_ssthresh(struct sock *sk)