[Systems] Load on treehouse

[Sascha Silbe]

Excerpts from Bernie Innocenti's message of Sun Aug 29 20:10:08 +0200 2010:

> Can we move these build slaves to housetree on an IPv6 subnet? SMparrish
> and rgs expressed interest in working on this.
BTW, is IPv6 to sunjammer working fine for you? It's broken for me for
several days now. Since squid isn't too smart about connecting to
IPv4/IPv6 multi-homed hosts, it's rather annoying (I have to abort and
resubmit every other HTTP(S) request).

> > by the way cpu usage score on treehouse:
> > 1) aslo-web
> > 2) lightwave
What on lightwave causes the CPU load (everytime I run top it's completely
idle so I can't tell)?

> I figured out why lightwave causes high load. From time to time, sks
> wakes up and trashes the disk for a few minutes. Sascha, why is that?
Ah, I already suspected that (and changed the configuration to verify my
suspicion, but didn't check Munin again yet).
SKS does a daily statistics calculation which is heavily IO-bound. A few
minutes doesn't sound bad, so in general it should be quite fine. The
reason it's a problem on treehouse is still the combination of

1. KVM hiding away any prioritisation (AKA ionice) done inside the VM
2. running high-priority (LDAP) and low-priority (SKS) servers inside
   the same VM (so we can't just ionice the entire VM).

So maybe we should move SKS into a new VM or at least a different,
equally low-priority one (that we will ionice).

Sascha

--
http://sascha.silbe.org/
http://www.infra-silbe.de/
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