| Message ID | 1367261091-28052-1-git-send-email-ycheng@google.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Mon, 2013-04-29 at 11:44 -0700, Yuchung Cheng wrote: > Linux immediately returns SYNACK on (spurious) SYN retransmits, but > keeps the SYNACK timer running independently. Thus the timer may > fire right after the SYNACK retransmit and causes a SYN-SYNACK > cross-fire burst. > > Adopt the fast retransmit/recovery idea in established state by > re-arming the SYNACK timer after the fast (SYNACK) retransmit. The > timer may fire late up to 500ms due to the current SYNACK timer wheel, > but it's OK to be conservative when network is congested. Eric's new > listener design should address this issue. > > Signed-off-by: Yuchung Cheng <ycheng@google.com> > --- Acked-by: Eric Dumazet <edumazet@google.com> -- 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
On Mon, Apr 29, 2013 at 2:44 PM, Yuchung Cheng <ycheng@google.com> wrote: > Linux immediately returns SYNACK on (spurious) SYN retransmits, but > keeps the SYNACK timer running independently. Thus the timer may > fire right after the SYNACK retransmit and causes a SYN-SYNACK > cross-fire burst. > > Adopt the fast retransmit/recovery idea in established state by > re-arming the SYNACK timer after the fast (SYNACK) retransmit. The > timer may fire late up to 500ms due to the current SYNACK timer wheel, > but it's OK to be conservative when network is congested. Eric's new > listener design should address this issue. > > 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: Yuchung Cheng <ycheng@google.com> Date: Mon, 29 Apr 2013 11:44:51 -0700 > Linux immediately returns SYNACK on (spurious) SYN retransmits, but > keeps the SYNACK timer running independently. Thus the timer may > fire right after the SYNACK retransmit and causes a SYN-SYNACK > cross-fire burst. > > Adopt the fast retransmit/recovery idea in established state by > re-arming the SYNACK timer after the fast (SYNACK) retransmit. The > timer may fire late up to 500ms due to the current SYNACK timer wheel, > but it's OK to be conservative when network is congested. Eric's new > listener design should address this issue. > > Signed-off-by: Yuchung Cheng <ycheng@google.com> Applied. Maybe -stable material? -- 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
On Mon, Apr 29, 2013 at 12:17 PM, David Miller <davem@davemloft.net> wrote: > From: Yuchung Cheng <ycheng@google.com> > Date: Mon, 29 Apr 2013 11:44:51 -0700 > >> Linux immediately returns SYNACK on (spurious) SYN retransmits, but >> keeps the SYNACK timer running independently. Thus the timer may >> fire right after the SYNACK retransmit and causes a SYN-SYNACK >> cross-fire burst. >> >> Adopt the fast retransmit/recovery idea in established state by >> re-arming the SYNACK timer after the fast (SYNACK) retransmit. The >> timer may fire late up to 500ms due to the current SYNACK timer wheel, >> but it's OK to be conservative when network is congested. Eric's new >> listener design should address this issue. >> >> Signed-off-by: Yuchung Cheng <ycheng@google.com> > > Applied. > > Maybe -stable material? Should be fine for -stable too. Thanks. -- 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_minisocks.c b/net/ipv4/tcp_minisocks.c index 05eaf89..0f01788 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -551,8 +551,13 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, * * Note that even if there is new data in the SYN packet * they will be thrown away too. + * + * Reset timer after retransmitting SYNACK, similar to + * the idea of fast retransmit in recovery. */ - inet_rtx_syn_ack(sk, req); + if (!inet_rtx_syn_ack(sk, req)) + req->expires = min(TCP_TIMEOUT_INIT << req->num_timeout, + TCP_RTO_MAX) + jiffies; return NULL; }
Linux immediately returns SYNACK on (spurious) SYN retransmits, but keeps the SYNACK timer running independently. Thus the timer may fire right after the SYNACK retransmit and causes a SYN-SYNACK cross-fire burst. Adopt the fast retransmit/recovery idea in established state by re-arming the SYNACK timer after the fast (SYNACK) retransmit. The timer may fire late up to 500ms due to the current SYNACK timer wheel, but it's OK to be conservative when network is congested. Eric's new listener design should address this issue. Signed-off-by: Yuchung Cheng <ycheng@google.com> --- net/ipv4/tcp_minisocks.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)