Re: Wierd context-switching issue on Xeon

Tom,

> So in the short term I think we have to tell people that Xeon MP is not
> the most desirable SMP platform to run Postgres on.  (Josh thinks that
> the specific motherboard chipset being used in these machines might
> share some of the blame too.  I don't have any evidence for or against
> that idea, but it's certainly possible.)

I have 3 reasons for thinking this:
1) the ServerWorks chipset is present in the fully documented cases that we
have of this problem so far.   This is notable becuase the SW is notorious
for poor manufacturing quality, so much so that the company that made them is
currently in receivership.   These chips were so bad that Dell was forced to
recall several hundred of it's 2650's, where the motherboards caught fire!
2) the main defect of the SW is the NorthBridge, which could conceivably
adversely affect traffic between RAM and the processor cache.
3) XeonMP is a very popular platform thanks to Dell, and we are not seeing
more problem reports than we are.

The other thing I'd like your comment on, Tom, is that Dirk appears to have
reported that when he installed a non-bigmem kernel, the issue went away.
Dirk, is this correct?

--
Josh Berkus
Aglio Database Solutions
San Francisco