[mpich-discuss] multi threading

[David R Anderson]

Ahh, thanks for that explanation.

Dave
---------------------------------------------------
David R. Anderson
Principal Engineer
D412, Radiation Analysis Section
Phone: (860)433-6584, FAX (860)433-3229
E-mail: danders3 at gdeb.com




Darius Buntinas <buntinas at mcs.anl.gov> 
Sent by: owner-mpich-discuss at mcs.anl.gov
04/18/2008 12:05 PM
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Subject
Re: [mpich-discuss] multi threading







By default, thread support is enabled at runtime, so unless you're 
debugging the MPICH2 library, you shouldn't use the 
--enable-threads=multiple option.  With runtime thread support, thread 
support is enabled only if the application calls MPI_Init_thread.  By 
enabling thread support only when needed you'll avoid the additional 
overhead associated with providing thread safety in single threaded 
processes.

-d

On 04/18/2008 09:10 AM, David R Anderson wrote:
> 
> I have mpich2 (1.0.6) installed on a Dell poweredge compute server with 
> Red Hat Linux installed.  The server is new and has 4-quad core 
> processors.  I have compiled mpich2 using the --enable-threads=multiple 
> option for configure.   After compiling mpi versions of several programs 

> I find that I get good speedup results up to 8 processors, however, no 
> benefit from 9-16.  There is a small drop in performance from 8-9 and 
> then by 16 processors has caught back up to the same speedup value as 
> with 8.
> 
> Is there something else I need in the config options, or is dual 
> threading the best that I can get?  I'd appreciate any advice.
> 
> Thanks in advance,
> 
> Dave
> ---------------------------------------------------
> David R. Anderson
> Principal Engineer
> D412, Radiation Analysis Section
> Phone: (860)433-6584, FAX (860)433-3229
> E-mail: danders3 at gdeb.com


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