Just for the records: I finally found the issue here. It's a problem
of both, alignment and cache thrashing. When using aligned memory
(e.g. via posix_memalign()) and using a suitable offset within that
memory, the effect goes away. So it's a processor effect, not a
compiler issue. :-)
Best
-Andr
On 16:37 Thu 09 Jul , Richard Guenther wrote:
> Depends on the GCC version used. First of all
>
> printAddress(&gridNew[0][0]);
> printAddress(&gridOld[0][0]);
>
> makes the addresses escape and GCC versions other than the
> current development trunk think that the malloced address c
On Thu, Jul 9, 2009 at 4:19 PM, Andreas Schäfer wrote:
> Hey guys,
>
> I noticed a strange performance hit in one of our stencil codes,
> causing it to run twice as long.
>
> To nail down the error, I reduced our code to the two attached demo
> programs. Basically they take two matrices and average
Hey guys,
I noticed a strange performance hit in one of our stencil codes,
causing it to run twice as long.
To nail down the error, I reduced our code to the two attached demo
programs. Basically they take two matrices and average each matrix
element with its four direct neighbors. Depending on
