I have ATS working, using raw devices now (12 x 15K RPM drives) and it is in more or less stock settings as far as the thread and memory setup.
I turned on the L4 redirect firehose and shot 800 req/s at it, and within about a minute, ATS started reporting errors connecting to *all* sites it was asked for and for all intents and purposes, "locked up." Didn't really hear from users as they're used to the Internet being wonky. :) Anyway, thing is... at first I thought this was ATS scalability settings but then I set it up to test with a single browser again and have discovered that I can successfully get ATS to exhibit the same behaviour with just a single computer and browser, and simply browsing! It just takes a bit longer. This is with ATS 3.0.0 beta, FWIW. So the question is... is this a tproxy thing where the computer has a set number of connections that fills up? Doesn't seem to be, netstat doesn't report more than about 4 connections from my browser at once. And if it's ATS... where to look? I think it may be, by the way... because ATS is what stops connecting to external sites. Lastly, load on the machine seems to go from 2.5 to 4.5 all the time that ATS is running, regardless of load. I thought this might be a poll/epoll issue but the config log tells me that epoll is being used (and the overall CPU time seems to show that this is true). I believe I may have bitten off more than I can chew here and may have to return to Squid. Which is sad, because ATS has some obvious advantages. But, ATS documentation/examples/experience are still quite lacking at this point.
