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

From: David Mosberger <>
Date: 2003-10-25 04:36:08
>>>>> On Fri, 24 Oct 2003 10:10:44 -0700, Stephane Eranian <> said:

  Stephane> Ionut, On Fri, Oct 24, 2003 at 06:26:55PM +0200, Ionut
  Stephane> 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.

  Stephane> Another thing to check is the syslog. Check to see if your
  Stephane> program is not getting "floating point software assist"
  Stephane> fault. That can slow you down significantly.

Note that on Red Hat you'd have to raise the dmesg level above WARNING
to see such messages (dmesg -n8 should do the trick).

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Received on Fri Oct 24 14:40:48 2003

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