[Beowulf] Gentoo in the HPC environment

[Prentice Bisbal]

On 07/01/2014 12:17 AM, Matt Wallis wrote:
> On 01/07/14 13:45, Jonathan Aquilina wrote:
>> This question probably sounds like a stupid one, but what difference 
>> in an
>> HPC environment and to parallel written code does compiler version make?
>
> Depends on the day of the week, the processor, the code, and your 
> cluster really.
>
> Sometimes code from GCC is faster, sometimes code from the Intel 
> compiler is faster.
> Some people write code that only compiles with the Intel compiler, or 
> link against libraries distributed with the compiler.
>
> Then of course you might have a BlueGene with PPC cores rather than 
> x86, and while the difference in performance between GCC for PPC and 
> the IBM XL compilers is slight these days, it wasn't always the case.

One of my researchers has found that his code that is integer-heavy runs 
up to 5x faster on our BG/P when compiled with GCC over the same code 
compiled with the IBM XL compilers. For floating point heavy codes, the 
IBM XL compiles produce much faster code.

>
> Intel also distributes highly tuned versions of some maths libraries 
> with their compilers, and libraries designed for offloading work to 
> the the Xeon Phi, without recompiling the application.
>
> And then when it comes time to debug why the application doesn't work, 
> commercial compiler suites often come with very good debugging tools.
>
> Matt.
>