[Beowulf] Re: vectors vs. loops

[Greg Lindahl]

On Wed, May 04, 2005 at 03:03:51PM -0400, Robert G. Brown wrote:

> Do compilers
> automatically use block prefetch and three phase implementations of the
> floating point involved?

I can't speak for other compilers, but we don't do block prefetch and
three phase loops, we do straight prefetch, and it works quite well.
It can be hard to stare at a paper advocating some particular
technique and understand if it actually beats the conventional method
of doing something; I have no idea why the conventional method works
so poorly for him, but our current STREAM numbers are equal to his
fancy method without all the pain.

-- greg