Re: MySQL4 on Linux with Intel Hyperthreading CPUs?

[Mark Matthews]

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Keith Sauvant wrote:

Hi Group,

I have a new dedicated mysql 4.0.5 server running redhat 8.0 that we

are testing.

The new server is a dual Intel Xeon 2.4GHZ with hyperthreading

enabled, so Linux

thinks there are 4 cpu's rather than the 2 real CPU's.

I have a similar hardware running mysql 3.23.52 on linux. In my special
case mysql has to handle few but very straining queries (running 10-30
seconds). As of my experience, mysql is not able to use both physical
processors to process one of these jobs... it really bunches two
"virtual" processors (even though top shows 0% load for the 3 remaining
processors) but not "physical processor spanning".

I would like one single mysql process to make use of all available cpu
capacity if no concurrent processes demand attention. But: is this
possible using mysql 3.x?

This would require operating system support for balancing a single process or thread across multiple CPUs, which I've never heard of (but might exist in some more exotic operating systems).

In MySQL, each connection, and thus each query, maps to a thread. On almost all operating systems and hardware, any one thread or process executes on a single CPU at any one time. CPU cycles are not generally a 'sharable' resource, except in parallel processing type scenarios, which requires software to be built specifically for that kind of operation, and which is only useful to solve certain specific types of problems.

-Mark


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__ ___ ___ ____ __
/ |/ /_ __/ __/ __ \/ / Mark Matthews <[EMAIL PROTECTED]>
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB, Full-Time Developer - JDBC/Java
/_/ /_/\_, /___/\___\_\___/ Flossmoor (Chicago), IL USA
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