Author: Dan Newman
Date: 04:03:18 10/30/00
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On October 29, 2000 at 09:15:28, David Rasmussen wrote: >When I compile my program on Windows 2000 in VC++ I get ~150000 nps on a >Cel300A@464, but when I use the exact same compiler (or even the same >executable) on win98 I get ~60000 nps !!! > >And I know its not win98 thats the problem. I have run it on win98 lots of time >and compiled it with both gnu and borland c++ builder, at got fine results. > >Whats wrong here? > >P.S. the machine with win98 is an athlon 650 Mhz. Can it be the athlon that >doesnt like the heavy bitboard usage ? I benchmarked my bitboard program, Shrike, on a number of different machines, including an Athlon 800. Here's some of what I got: Cel/400 472 knps P3/600 (Katmai) 555 knps P3/800 (CuMine) 909 knps Ath/800 698 knps This was all with the same executable, compiled with MSVC. I've wondered what's going on with the Athlon results. One of my theories is that the Athlon doesn't have a very fast implementation of the BSF/BSR instructions, but I haven't looked into at all--just idle speculation. The Athlon (by its specs) should be *really* good. My program really seems to like large fast caches, so I expected it to do a lot better on the Athlon... If you aren't using BSF/BSR for finding first/last bit, then it must be something else. Maybe MSVC optimizations are very Pentium specific. -Dan.
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