"J?r?me M. Berger" <jeb### [at] freefr> wrote:
> You should retry with 
> the latest source code I posted (at 11am French time), which is the 
> one I used on the Core2.

  I was indeed using the wrong version of your program. I took the correct
version and now the timings are much more like what I would expect.

  To recapitulate, your timings with the Core 2 Duo were:

Empty loop:       2173ms
Kiss64 (int):     7541ms
Kiss64 (dbl):    15844ms
Alvo (floor):    24778ms
Alvo (cast):      8469ms
Alvo (tmp+cast):  8473ms
Isaac:            7810ms

  With my P4, using gcc 4.3.1, the timings are:

Empty loop:       1221ms
Kiss64 (int):    32455ms
Kiss64 (dbl):    65092ms
Alvo (floor):    21088ms
Alvo (cast):     17937ms
Alvo (tmp+cast): 17939ms
Isaac:            6785ms

  The Kiss64 results are very significantly slower (both by a factor of
about 4). With the integer version that's not a big surprise because
long longs are necessarily a bit slow on a 32-bit system. The slowness
of the floating point version is a bit more surprising, though.

  Tha Alvo versions are slower only by a factor of about 2, except for
the floor version, which is actually faster on my system. Curious. Maybe
floor() can be done faster on a P4 than on a Core 2.

  The P4 still beats the Core 2 on the Isaac test (although not by much),
which might not be all that surprising given the raw clockrate difference.
This might also explain the significant difference in the empty loop test.

-- 
                                                          - Warp

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