Re: Itanium2@900MHz slower than alpha@666MHz ?

From: Matthew Wilcox <>
Date: 2003-10-25 02:49:29
On Fri, Oct 24, 2003 at 06:26:55PM +0200, Ionut Georgescu wrote:
> Yes, it is a 1.5MB cache CPU.
> But it might be more than just cache misses. When running with a 256x256
> grid, I am actually using 3 256x257 matrices, which is slightly over
> 1.5MB.  I just made a comparison with a 32x32 grid and the difference is
> the same: alpha 10.294s, zx2000 14.777s . -O3 is only by 0.4s faster
> than -O2 in this case.
> The variations are within +-0.02s between runs (for the 32x32 case).
> Is there a way to test the bandwidth of the cache ? Because I think the
> alphas have actually 2MB of L2 cache, not L3.

I don't know about testing cache bandwidth, but /proc/pal/cpu0/cache_info
gives various stats on how the different levels of cache play together
on ia64.

"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk
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Received on Fri Oct 24 12:55:24 2003

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