[Pw_forum] Re: Woodcrest vs Opteron performance in pwscf calc.

[Huiqun Zhou]

Hi, Axel and list users,

>
> actually, it is. some people here spend a lot of money
> on new machines and figuring out what is the best deal
> for a specific application needs a lot of testing. so
> every contribution is important.
>

So, I continue to post here ;-)

>
> one thing to check when using intel MKL is, whether it is running in
> multi-threaded mode and thus getting better results on a 'half-loaded'
> machines. for that, you may want to re-run the jobs with the
> environment variable OMP_NUM_THREADS set to 1. secondly, memory
> contention is a problem, so it would be interesting to see the
> performance, if you run 4 serial jobs at the same time.
>

OMP_NUM_THREADS had been set to 1 in all my tests.

>
> there is a way to make (the gcc) ACML compatible with the intel
> compiler (at least for packages that use only double precision
> functions), see:
> https://www.liniac.upenn.edu/wiki/tiki-index.php?page=acml+for+CMM
>
> it would be nice to see, how using ACML would affect
> the performance in this case.
>

If anyone can contribute a makefile for using PathScale compiler, the test 
will
be handy. I have pathscale version of ACML 2.8. Unfortunately, I haven't
succeded in compiling QE with this compiler yet.

Best Regards,


Huiqun Zhou