On 01/04/2012 11:16 AM, Dave Taht wrote: > > 3) since game manufacturers have noted the diffserv marking in > PFIFO-FAST, what do these queuing disciplines currently do? > They pay no attention to diffserv. It's possible we have a small > problem here, but I'd wager not.
That's not what I understand from talking to Andrew McGregor: he says the game companies have figured out that diffserv marking is respected by PFIFO-FAST, and are marking appropriately (since most current routers are doing PFIFO-FAST, as it's been the default in Linux for quite a while. But the flows may be sparse enough it may not matter so much. I think we need to understand this in more depth... > > If their packets are not saturating the link, and/or it's per > host FQ, they are going to win. > > isochronous flows (like voice, even (especially) skype) should respond well to > this stuff, too. do, actually. skype is nicer now. > > > footnotes: > > 1: the 'slower flows gain priority' question is my gravest concern > (eg, ledbat, bittorrent). It's fixable with per-host FQ. > > 2: I note that identifying "a host" is harder than it was in nagle's > day - with multiple protocols in use a hash against an IP address is > not accurate, nor, by the time you hit the egress interface, do you > have a mac address to use. > > I did not solve that problem in my home router gw/aqm/fq prototype. > The approximation was a hash that matched an ip or ipv6 address. > > 3: (and conversely, existing elephants slow down). (and when you drop > packets there is a good question, but you do end up with classic tail > drop behavior in both QFQ and SFQ on a per flow basis. You can get > head drop out of QFQ, actually) > > 4: especially in variable bandwidth scenarios, the depth of even the > fairest queue needs to be managed somehow. > > But I can live with the nearly two orders of magnitude of basic > latency improvement we've got now, as well > as the probability this induces of doing smarter/effective queue > length management, and keep getting the bugs out of it.... > >> > > _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
