Re: [gentoo-user] Changing compilers

[Michael Mol]

On Mon, Mar 19, 2012 at 10:18 AM, Andrew Lowe <agl@×××××××.au> wrote:
> On 03/19/12 22:02, Michael Mol wrote:
>> On Mon, Mar 19, 2012 at 8:32 AM, Mark Knecht <markknecht@×××××.com> wrote:
>>> On Sun, Mar 18, 2012 at 10:26 PM, Andrew Lowe <agl@×××××××.au> wrote:
>>>> Hi all,
>>>>    Has anyone played around with the various "better known" compilers on
>>>> Gentoo? By "better known", I'm referring to gcc, Intel, llvm, pathscale. My
>>>> situation is that I've just started my PhD which requires me to do Finite
>>>> Element Analysis, FEA, and Computational Fluid Dynamics, CFD, and I want to
>>>> find the "best" compiler for the job. Before anyone says "Why bother, XXX
>>>> compiler is only 1 - 2% faster than gcc", in the context of the work I'm
>>>> doing this 1 - 2% IS important.
>>>>
>>>> What I'm looking for is any feedback people may have on ability to compile
>>>> the Gentoo environment, the ability to change compilers easily, gcc-config
>>>> or flags in make.conf, as to whether the compiler/linker can use the
>>>> libraries as compiled by gcc on a "standard" gentoo install and so on.
>>>> Obviously there is much web trawling to be done to find what other people
>>>> are saying as well.
>>>>
>>>> Any thoughts, greatly appreciated,
>>>>       Andrew Lowe
>>>>
>>>>
>>>
>>> Think CUDA
>>
>> Yes. And as a convenient side-effect, it offers a great excuse to
>> upgrade your video card with some regularity. The performance of
>> mid-grade and high-grade video cards continues to improve rapidly.
>>
>
>        Sorry, can't do that, I'm using epic,
>
> http://tinyurl.com/83l5o3z
>
> which currently ranks at 151 in the top 500 list :) It's amazing how
> fast this list changes, 6 months ago, this machine was at 107 and 6
> months before that 87.

That does change things a bit. I don't know Epic's structure or their
upgrade plans, but if you're confident it's not going to have GPGPU
capabilities, then CUDA and OpenCL are less useful for you. OpenCL, at
least, still handles per-CPU and per-node job dispatching, though. And
that's still likely to be useful for performing on huge matrices.

To answer your original question: No, I haven't done much with
anything other than gcc on Gentoo. What you *should* do is grab each
compiler (trial versions, if necessary) and test them to find which
gives you the best results. It's my understanding PhD programs involve
getting things done right, not so much quickly or easily. Best to be
methodical about it.

-- 
:wq