Each of 4 individual query only took <0.6 seconds,
there is no other clients, it hardly to believe taht
mysql query performance will degrade 300% (from <0.6s
to ~1.9s) if we have 4 concurrent connections...
As far as I know, MySQL should be able to handle
hundreds of connections on a single CPU box without
degrading performance like above.
Thanks
HT
--- Marc Slemko <[EMAIL PROTECTED]> wrote:
> On Mon, 7 Jun 2004, Haitao Jiang wrote:
>
> > Marc
> >
> > mysqld runs on a very powerful Operton machine
> with
> > 16GB memory and barely any other application
> process
> > running, it is hard to believe that a simple
> select
> > that runs under 2 second will utilize all the
> > resources...that is why I tend to think there is
> > something in the mysql set up that caused
> this...any
> > idea where I should look?
>
> How many processors?
>
> If there is only one and the query is CPU bound (as
> it probably is if
> everything is cached, given 16 gigs of ram), then
> why shouldn't it
> use all the CPU?
>
> Or, to phrase the question differently: why should
> the query take 2
> seconds to run if there are free resources?
>
> Now, on a multiprocessor box it clearly starts to
> get more complicated.
> mysql has no capability to spread one query across
> multiple CPUs
> in parallel, and while it can spread multiple
> queries across CPUs the
> scalability has its limits.
>
> The fact that is a "simple query" is irrelevant
> (some of the simplest can
> be the slowest if it has to do a full table scan).
> From the fact
> that it takes 2 seconds it is clear it is not an
> entirely trivial query.
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