Re: SMP performance degradation with sysbench

[Rik van Riel]

J.A. MagallÃn wrote:
> On Mon, 26 Feb 2007 23:31:29 -0500, Rik van Riel <riel@xxxxxxxxxx> wrote:
>
> > Hiro Yoshioka wrote:

> > > Another question. When the number of threads exceeds the number of
> > > CPU cores, we may get a lot of idle time. Then a workaround of
> > > MySQL is that do not creat threads which exceeds the number
> > > of CPU cores. Is it right?
> > Not really, that would make it impossible for MySQL to
> > handle more simultaneous database queries than the system
> > has CPUs.
>
> I don't know myqsl internals, but you assume one thread per query.
> If its more like Apache, one long living thread for several connections ?

Yes, they are longer lived client connections.  One thread
per connection, just like Apache.

> Its the same to answer 4+4 queries than 8 at half the speed, isn't it ?

That still doesn't fix the potential Linux problem that this
benchmark identified.

To clarify: I don't care as much about MySQL performance as
I care about identifying and fixing this potential bug in
Linux.

--
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the best in the world, and those who believe it already is.  Each group
calls the other unpatriotic.
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