On Thu, 2019-12-05 at 08:57 -0800, Ben Greear wrote: > On 12/5/19 8:49 AM, Johannes Berg wrote: > > On Thu, 2019-12-05 at 08:37 -0800, Ben Greear wrote: > > > > > > All this seems to mean that the TCP stack isn't feeding us fast enough, > > > > but is that really possible? > > > > > > Does UDP work better? > > > > Somewhat, I get about 1020-1030 Mbps. But still a TON of "TXQ of STA ... > > is now empty" messages. Say this run got about 15 per second of those. > > It would seem that it is not some issue with TCP stack then? Hmm, yeah, maybe not then. Something more general in the stack? I just can't think of anything. > In general, UDP uses more CPU to send from user-space than TCP > because of TSO, etc. Sendmmsg can help a bit, but it is a bit painful > to code against so things like iperf do not use it, at least ones I've > looked at. True. > Can you provide some details on how you are generating this load? Using chariot. I don't really know it well, just the testers use it. > For what it's worth, we've seen about 1.9Gbps download goodput > when using ax200 as a station receiving traffic from 160Mhz AP. > I don't have any reports of > 1Gbps of upload performance though, > not sure our user with the fast AP has done much upload testing... :) > > > or pktgen? > > > > I haven't really tried, the setup is a bit complicated ... and it's > > nowhere near me either :) > > Yeah, it will likely crash your system unless you apply years-old patches I posted > too :) > > But, at least with pktgen, you can be quite sure it is not some slowdown farther up > the stack that is causing the problem. True. johannes
