Hi Michael, On Mon, Mar 02, 2020 at 12:41:57PM +0100, Michael Tuexen wrote: > > In wireshark, I can see that up to 9 DATA chunks are aggregated into each SCTP > > packet. However, it typically takes the stack 203-201ms to send a SACK to each > > That looks suspicious. It seems this is the 200ms delayed ACK timer. That is fine. > The question is why the sender is not sending more? I guess you can work around this > issue by disabling the Nagle Algorithm: > https://tools.ietf.org/html/rfc6458#section-8.1.5 > Enable SCTP_NODELAY on the sender side. Does that fix the issue? > However, Nagle should not step into the game here... I was thinking of SCTP_NODELAY before, but didn't do it as I thought it would only impact the lower latency bound in sporadic communication, but not throttle the transmit message rate? I've just tried your suggestion, and indeed: with SCTP_NODELAY=0 10000 DATA chunks of 150 bytes each in 19.59 seconds: 510.53 DATA chunks per second with SCTP_NODELAY=1 10000 DATA chunks of 150 bytes each in 0.26 seconds: 38360.42 DATA chunks per second So AFAICT there now is a work-around... but still I assume there is a bug in lksctp if it throttles the overall message rate down to 1.3% of what it could be when Nagle is enabled? Regards, Harald -- - Harald Welte <laforge@xxxxxxxxxxxx> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)
