Bad routing performance on 500Mhz Geode LX with CURRENT, ipfw and mpd5 (was: ipfw, "ip|all" proto and PPPoE -- does PPPoE packets passed to ipfw?)

[Lev Serebryakov]

Hello, Adrian.
You wrote 30 августа 2012 г., 23:01:12:

>>   Yes, it is only 500Mhz Geode LX, but it is only 40 mbit/s and
>> 4.5Kpps in both directions, nothing like full 100Mbit or more, and
>> I've learned "empirical" rule/heuristics about 1Gbit(!) per 1Ghz(!)
>> for softrouters, So, theoretically, 40mbit should not be a problem at
>> all for this hardware.
AC> It honestly shouldn't be that bad, but without dumping a bunch of
AC> effort into profiling (even if it's just sampled profiling via gprof)
  Is it possible to use gprof with kernel? As here is no userland
processes involved: PPPoE is porcessed by netgrpah, routing & ipfw is
kernel stuff too...

AC> I won't know whether that's "good" or not.

>>   And now I have not-working WiFi (this box is also AP) when wired
>> traffic is high (wifi speed drops down to 100KB/s from 2.5-3MB/s
>> without wired traffic), userland freezes under load (very bad with
>> ULE, better with 4BSD), and inability to pass through 40Mbit in both
>> directions simultaneously.
AC> Hm. What about disabling preemption and see if that helps? I still
AC> haven't fully debugged/diagnosed why preemption acts weirdly on my
AC> mips24k boards (which is why all the mips24k Atheros SoC's have 4BSD +
AC> no PREEMPT.)
  I'll try it.

  Also, I noticed, that with any scheduler it could not route 40Mbit
 in BOTH directions simultaneously, and downstream has priority. When
 there is no much of downstream, it upload at 40-45Mibt/s, and when
 downstream is 40-45Mibt/s upstream could be only about 20Mbit/s.

-- 
// Black Lion AKA Lev Serebryakov <lev at FreeBSD.org>