All current TCP implementations have a minimum window size of two segments. If you have 20 open connections, then the minimum bandwidth TCP will attempt to consume is (2 segments * 20 connection)/latency. If you have very low latency relative to your bandwidth, the sender will not respond to congestion.
On Thu, Apr 6, 2017 at 9:47 PM, cloneman <clone...@gmail.com> wrote: > Hi, > > Appologies in advance if this is the wrong place to ask, I haven't been > able to locate an official discussion board. > > I'm looking for any comments on Steam's game distribution download system > - specifically how it defeats any bufferbloat mitigation system I've used. > > It seems to push past inbound policers, exceeding them by about 40%. That > is to say, if you police steam traffic to half of your line rate, enough > capacity will remain to avoid packet loss, latency, jitter etc. Obviously > this is too much bandwidth to reserve. > > Without any inbound control, you can expect very heavy packet loss and > jitter. With fq_codel or sfq and taking the usual recommended 15% off the > table, you get improved, but still unacceptable performance in your small > flows / ping etc. > > The behavior can be observed by downloading any free game on their > platform. I'm trying to figure out how they've accomplished this and how to > mitigate this behavior. It operates with 20 http connections > simultaneously, which is normally not an issue (multiple web downloads > perform well under fq_codel) > > Note: in my testing cable and vdsl below 100mbit were vulnerable to this > behavior, while fiber was immune. > > Basically there are edge cases on the internet that like to push too many > bytes down a line that is dropping or delaying packets. I would like to see > more discussion on this issue. > > I haven't tried tweaking any of the parameters / latency targets in > fq_codel. > > > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat > >
_______________________________________________ Bloat mailing list Bloat@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/bloat
