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Posted by Erland Sommarskog on 06/29/05 00:41
(kev@earlshilton.com) writes:
> I have a sql 2000 server with 8 processors, server settings are as
> default. I read on Technet that it is good practise to remove the
> highest no. processors from being used for parallelism, corresponding
> to the no. of NICs in the server. One of our 3rd party developers has
> recommended only allowing one processor to be used as there is a
> performance hit by the server working out which processor to use. Does
> anyone have a definitive answer to this? I suspect he's wrong but I'd
> like some hard evidence if possible, thanks.
In fact, it is not uncommon to see SQL Server pick a parallel plan
which is considerably slower than a non-parallel plan. However, I don't
think turning of parallelism entirely is really a good thing. There
are probably cases where you parallelism can help you to speed up
queries as well.
However, if you processors are hyperthreaded, you set "Max degree of
parallelism" to be at most 8, that is the number of physical processors.
--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se
Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techinfo/productdoc/2000/books.asp
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