On Mon, Jul 23, 2018 at 8:49 PM Lawrence Brakmo <bra...@fb.com> wrote: > > We observed high 99 and 99.9% latencies when doing RPCs with DCTCP. The > problem is triggered when the last packet of a request arrives CE > marked. The reply will carry the ECE mark causing TCP to shrink its cwnd > to 1 (because there are no packets in flight). When the 1st packet of > the next request arrives, the ACK was sometimes delayed even though it > is CWR marked, adding up to 40ms to the RPC latency. > > This patch insures that CWR marked data packets arriving will be acked > immediately. ... > Modified based on comments by Neal Cardwell <ncardw...@google.com> > > Signed-off-by: Lawrence Brakmo <bra...@fb.com> > --- > net/ipv4/tcp_input.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-)
Seems like a nice mechanism to have, IMHO. Acked-by: Neal Cardwell <ncardw...@google.com> Thanks! neal
