On 07/24/2018 04:15 AM, Neal Cardwell wrote: > 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>
Should this go to net tree instead where all the other fixes went? Thanks, Daniel
