| Message ID | 1378420569-12370-1-git-send-email-ycheng@google.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, Sep 5, 2013 at 6:36 PM, Yuchung Cheng <ycheng@google.com> wrote: > In commit 0f7cc9a3 "tcp: increase throughput when reordering is high", > it only allows cwnd to increase in Open state. This mistakenly disables > slow start after timeout (CA_Loss). Moreover cwnd won't grow if the > state moves from Disorder to Open later in tcp_fastretrans_alert(). > > Therefore the correct logic should be to allow cwnd to grow as long > as the data is received in order in Open, Loss, or even Disorder state. > > Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> neal -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Neal Cardwell <ncardwell@google.com> Date: Thu, 5 Sep 2013 19:56:59 -0400 > On Thu, Sep 5, 2013 at 6:36 PM, Yuchung Cheng <ycheng@google.com> wrote: >> In commit 0f7cc9a3 "tcp: increase throughput when reordering is high", >> it only allows cwnd to increase in Open state. This mistakenly disables >> slow start after timeout (CA_Loss). Moreover cwnd won't grow if the >> state moves from Disorder to Open later in tcp_fastretrans_alert(). >> >> Therefore the correct logic should be to allow cwnd to grow as long >> as the data is received in order in Open, Loss, or even Disorder state. >> >> Signed-off-by: Yuchung Cheng <ycheng@google.com> > > Acked-by: Neal Cardwell <ncardwell@google.com> Applied, thank you. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 1969e16..894bc17 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3162,16 +3162,14 @@ static inline bool tcp_may_raise_cwnd(const struct sock *sk, const int flag) /* If reordering is high then always grow cwnd whenever data is * delivered regardless of its ordering. Otherwise stay conservative - * and only grow cwnd on in-order delivery in Open state, and retain - * cwnd in Disordered state (RFC5681). A stretched ACK with + * and only grow cwnd on in-order delivery (RFC5681). A stretched ACK w/ * new SACK or ECE mark may first advance cwnd here and later reduce * cwnd in tcp_fastretrans_alert() based on more states. */ if (tcp_sk(sk)->reordering > sysctl_tcp_reordering) return flag & FLAG_FORWARD_PROGRESS; - return inet_csk(sk)->icsk_ca_state == TCP_CA_Open && - flag & FLAG_DATA_ACKED; + return flag & FLAG_DATA_ACKED; } /* Check that window update is acceptable.
In commit 0f7cc9a3 "tcp: increase throughput when reordering is high", it only allows cwnd to increase in Open state. This mistakenly disables slow start after timeout (CA_Loss). Moreover cwnd won't grow if the state moves from Disorder to Open later in tcp_fastretrans_alert(). Therefore the correct logic should be to allow cwnd to grow as long as the data is received in order in Open, Loss, or even Disorder state. Signed-off-by: Yuchung Cheng <ycheng@google.com> --- net/ipv4/tcp_input.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)