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From:Mark Matthews Date:December 12 2002 3:47pm
Subject:Re: MySQL4 on Linux with Intel Hyperthreading CPUs?
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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 <mark@stripped>
   / /|_/ / // /\ \/ /_/ / /__ MySQL AB, Full-Time Developer - JDBC/Java
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Thread
MySQL4 on Linux with Intel Hyperthreading CPUs?John Dell12 Dec
  • RE: MySQL4 on Linux with Intel Hyperthreading CPUs?Adam Erickson12 Dec
  • MySQL4 user table not showing GRANT privileges correctlyJohn Dell14 Dec
    • re: MySQL4 user table not showing GRANT privileges correctlyVictoria Reznichenko14 Dec
Re: MySQL4 on Linux with Intel Hyperthreading CPUs?Keith Sauvant12 Dec
  • Re: MySQL4 on Linux with Intel Hyperthreading CPUs?Mark Matthews12 Dec
RE: MySQL4 on Linux with Intel Hyperthreading CPUs?Mike Grabski12 Dec