[gmx-developers] BlueGene

[Roland Schulz]

Hi,

it was mostly wrong names in the #include statements.

It works on BlueGene/P and is much faster than the C non-bonded kernel
(about 2x). With this intrinsic C kernel one gets 18% of peak. Because
BlueGene doesn't have SIMD commands specific for single precision (thus it
does only 2 at a time instead of 4) the performance difference to Opteron is
greater than for double precision code. The performance difference to a
Barcelona 2.1Ghz core is 5.7x (at 20% peak).

Roland

On Wed, Jul 30, 2008 at 12:29 PM, Roland Schulz <roland at utk.edu> wrote:

> Hi,
>
> it seems that the blugene non-bonded kernel in the CVS version is
> incomplete. E.g. the nb_kernel_bluegene_test_asm.h is missing as far as I
> can see. The gromacs wiki for bluegene explains how to get the kernel
> generated by mknb to work. Also on the mailinglist all the messages I found
> about BlueGene were about mknb and not abou the bluegene specifik kernel.
>
> Could it be that it is incomplete do one has to do somethng to generate
> these files?
>
> Roland
>
>
> On Wed, Jul 30, 2008 at 11:45 AM, Berk Hess <hessb at mpip-mainz.mpg.de>wrote:
>
>> Hi,
>>
>> Mathias Puetz from IBM wrote non-bonded kernels for BlueGene/L.
>> I don't know if these are also used for BlueGene/P.
>> If there are problems, he would be the person to contact.
>>
>> Berk.
>>
>>
>> Roland Schulz wrote:
>>
>>> Hi,
>>>
>>> has someone looked at the non-bonded kernels for BlueGene/P? Based on the
>>> assembler produced by the compiler, it does no SIMD, runs out of registers
>>> and does unnecessary rounding.
>>>
>>> Are there plans for a PPC450 assembler kernel?
>>>
>>> Roland
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