Mark Rae wrote:
On Wed, Oct 19, 2005 at 12:32:36AM -0700, William Yu wrote:
Expect to need to upgrade to later Linux cores though. Previous kernel
on this server was 2.6.9+ (FC3 64-bit) -- promptly kernel panic'd upon
install of the DCs. FC3 installer did the same thing. Went to FC4
(2.6.11+) and it has run perfect for the past 3 months. We'll probably
do a yum update to 2.6.13+ to take advantage of the better NUMA code now
that we've successfully done this update on a less critical server.
You should definitely do the upgrade to 2.6.13, the previous
versions had problems were they would allocate memory to
the wrong bank of memory when using dual core CPUs. So you
would find only about a 20% improvement over a single core.
With the newer kernels you should find that a dual core will
be giving you about 80% increase over a single core.
I'm not experiencing this problem right now because I have NUMA disabled
in the BIOS. :) I'm not sure NUMA will help that much for Postgres due
to Postgres shared memory + OS caching architecture -- but I'll run it
with NUMA on for a week and then compare it to NUMA off after we do the
kernel upgrade. (Ordinarily, I would be afraid to do this type of
testing on a production server but this 2xDC is so freaking fast, I can
afford to give away 80%+ of the processing power and still be within my
performance target.)
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