Tor client performance (was Re: URGENT: patch needed ASAP for authority bug)

[Scott Bennett]

     On Thu, 22 Apr 2010 11:31:45 +0200 Olaf Selke <olaf.selke at blutmagie.de>
wrote:
>Roger Dingledine wrote:
>> 
>> Attached is that patch. It only applies against git head, so if you
>> prefer tarballs, check out
>> http://freehaven.net/~arma/tor-0.2.2.12-alpha-dev.tar.gz
>
>at least the situation has changed :-)
>
>On my tiny middleman "Ilka" the number of open tcp sessions dropped from
>10k to less than 500 and so far not going to increase again. Good! This
>should solve most router problems for residential users.

     Most of the electronics-store routers that people use at home in the
U.S. seem to have trouble handling more than a couple of hundred entries
in their NAT tables and/or state tables.  (That's the main reason I gave
up on those as gateways and switched to letting FreeBSD handle that sort
of thing.  It's state tables can be pretty much as gigantic as they need
to be.)  500 would still be too many for those, but 10,000 is indeed
ridiculous for a 50 KB/s relay. :-)
>
>The situation on my exit "blutmagie" is somewhat different. Number of
>open tcp sessions dropped as well. On the other hand ratio of new
>connections per second increased. So far I'm not sure how throughput/cpu
>load ratio is affected. Roger's patch has been started this morning at
>07:30 local time. Pls look here http://torstatus.blutmagie.de/public_mrtg/

     Yes, except for the CPU utilization, it does look much better now.
>
>By now I no longer consider the cpu load issue being a bug. It looks

     I still say that a major part of the problem *is* a bug, but one
primarily of hardware design, i.e., the "small TLB" problem.

>like even a fast Intel E8600 cpu can't cope with blutmagie's exit
>traffic. Investing in new hardware won't help either as long as nearly
>all cpu time is spent within the main thread.
>
     You still have the option of running two processes, each with a bit
over half the throughput of the single process you currently run.


                                  Scott Bennett, Comm. ASMELG, CFIAG
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