"Merlin Moncure" <[EMAIL PROTECTED]> writes:

> heh, our apps do tend to be CPU bound.  Generally, I think the extra CPU
> horsepower is worth the investment until you get to the really high end
> cpus.

I find that while most applications I work with shouldn't be cpu intensive
they do seem end up being cpu bound quite frequently. What happens is that 90%
of the workload has a working set that fits in RAM. So the system ends up
being bound by the memory bus speed. That appears exactly the same as
cpu-bound, though I'm unclear whether increasing the cpu clock will help.

It's quite possible to have this situation at the same time as other queries
are i/o bound. It's quite common to have 95% of your workload be frequently
executed fast queries on commonly accessed data and 5% be bigger data
warehouse style queries that need to do large sequential reads.

Incidentally, the same was true for Oracle on Solaris. If we found excessive
cpu use typically meant some frequently executed query was using a sequential
scan on a small table. Small enough to fit in RAM but large enough to consume
lots of cycles reading it.


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