[GRLUG] large systems performance

[Tim Schmidt]

So today was my first chance to work with a new box we built just
yesterday...  it's got 2x quad-core opterons and 32Gb ram.  I noticed
something interesting about it's performance characteristics under
load as compared to typical desktop boxen: it's MUCH more responsive
in interactive situations under high load than any other machine I've
ever worked with.  Today I had it up to > 1300 15 minute load average
running about 4000 processes, each of which doing real honest work,
and it was still quite pleasant to launch applications, switch between
VTs, cd around filesystems, etc.  I guess all the other boxes I've
ever worked with (< 10Gb ram, all of them) were forced to swap before
supporting enough processes to get the load that high, thus killing
interactivity and artificially bloating the load at the same time.
I'm pretty impressed that, with enough ram, even a box doing about
150x as much work as it should (1300 / 8 = 162.5) can still feel
'snappy'.  :)

This sort of stuff isn't too far off from where high-end desktops are
now (technically, there's nothing stopping this machine from being a
desktop)...  Can't wait until it gets cheap enough to think about for
home.

--tim