On Tue, Nov 9, 2010 at 11:10 AM, Sandeep Srinivasa <sss@clearsenses.com> wrote:
> hi,
> I am the OP.
> With due respect to everyone (and sincere apologies to Richard Broersma), my
> intention was not to create a thread about MySQL/Oracle's business
> practices.
Hehe, we head off on tangents. It's common, don't worry.
> It was about the technical discussion on Highscalability - I have been
> trying to wrap my head around the concept of multiple core scaling for
> Postgres, especially beyond 8 core (like Scott's Magny Coeurs example). My
> doubt arises from whether Postgres depends on the kernel scheduler for
> multiple CPU/core utilization.
> If that is the case, then does using FreeBSD vs Linux give rise to any
> differences in scaling?
All multi-process applications like pgsql have to depend on the OS
kernel scheduler to get their processes run. But in terms of scaling,
that's usually not the biggest issue, it's getting rid of choke points
in the kernel like linux's much earlier versions having one big spin
lock on huge chunks of the kernel. That's been gone a long time, but
as the number of cores keeps going up, new chokepoints are found and
fixes in both Linux and BSD.
> Taking the question one step further, do different Linux kernels (and
> schedulers) impact Postgres scalability ? The Phoronix Test Suite already
> tests linux kernel releases for regressions in performance w.r.t postgres DB
> performance
The IO scheduler mostly just gets in the way on bigger machines with
battery backed caching controllers and / or SAN arrays.
> (e.g http://www.phoronix.com/scan.php?page=article&item=linux_perf_regressions&num=1),
> but doesnt particularly focus on multiple cores.
> Is it something that should be benchmarked ?
Yes. Sadly, to do so you really need a $7500 machine
