Re: Benchmarking L2 cache on the Alpha 21264

From: Christoph Best (c.best@fz-juelich.de)
Date: Tue Jun 06 2000 - 09:27:52 EST

Hi everybody,

thanks for all the help. I think the problem I am seeing is the lack
of page coloring. I will try Joseph Martin's kernel patch asap - we
are very interested in making efficient use of the L2 cache as it is
so big (4 MB on some of our machines).

In particular, page coloring should be a very good idea for cluster
nodes where we do not care about the actual performance of the kernel
page allocator (just running one process a long time in a fixed page
setup), but the penalties for cache misses are very high. We easily
see a factor of three in MFlops numbers between L1 cache and memory.

BTW, we use the Compaq compiler which gives about 20% more MFlops than
the gnu compiler in L1 cache.

Thanks again
-Chris 

-- 
Christoph Best                                        c.best@computer.org
John von Neumann Institute for Computing/DESY   http://www.oche.de/~cbest

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