ng_dummynet

Did some online debugging yesterday.

We've had one system with high load.

As for now i cannot exactly tell what is causing the high CPU load.

During the test i didn't touch the IPFW QUEUE system which is responsible for the policing. In fact, before reinitializing netgraph system experinced 70-80 CPU load (both cores the same 70-80) persent. At that moment there were 35-45K packets.

After netgraph reinit load dropped to 10-15 percent of each core. Pretty strange. The next thing to suspect was number of flows in ng_state. Before reinit there were about 120K. Right after init system collected 40K flows and load was 10-15 percent, in next 15 minutes it's rised to 80K flows, load raised substantioanaly - 2-5 percent.

Interestingly, complete removal of netgrpah processing doesn't result in significant CPU utulisation reduce - same 10-15% on tasq. Which means some part of netgraph is killing the performance.

So, to conclude: i am not sure that the problem is dummynet, but at least eliminating dummynet will allow to overcome 3K users (6k pipes) per system limit.

I've called it ng_dummynet. The thing is in process now. Yesterday i've did skeleton. Thing is supposed to be used together with ng_car which will be created per user basis. For now it is able to pass traffic uplink <-> downlink. Hoping to finish it by tommorow.