Re: [tor-relays] How effective is "NumCPUs"?

[Nick Mathewson <nickm@xxxxxxxxxxxxx>]

On Fri, Jan 24, 2014 at 4:49 AM, Alexander Dietrich
<alexander@xxxxxxxxxxx> wrote:
> Hello,
>
> a relay I'm running is currently at about 0.80 load average. It has a
> dual-core CPU and I have configured "NumCPUs 2". I'm still in the process of
> finding the bandwidth limit.
>

So, others have answered pretty well, but I'll add a little too.

Right now, Tor uses multiple cores to parallelize circuit extension
handshakes, but not much else.  I'm hoping that in future versions we
can make serious progress on getting more of our crypto
parallelized[*] to better take advantage of more cores, but for right
now, NumCPUs is a good thing, but is not actually adequate for evenly
dividing your Tor process's CPU load among a larger number of cores.

[*] See eg discussion at
https://trac.torproject.org/projects/tor/wiki/org/projects/Tor/MultithreadedCrypto
.  The design there is still sound, but it needs some C hackers with
spare time.

-- 
Nick
_______________________________________________
tor-relays mailing list
tor-relays@xxxxxxxxxxxxxxxxxxxx
https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays