Author: Vincent Diepeveen
Date: 16:59:15 09/15/01
Go up one level in this thread
On September 14, 2001 at 17:51:46, Robert Hyatt wrote: >On September 14, 2001 at 15:54:40, K. Burcham wrote: > >> >> >>below is part of an artical that i read on the net. >>i know you could get real technical about 64 bit. not necessary >>but here is my question. >>if we have two processors both 1500 mhz. both same brand. but "a" >> has 32 bit 1500 mhz with 32 bit program. >>"b" has 64 bit 1500 mhz with 64 bit program. >> >>how would a kns benchtest compare with these two examples? >>so if in example "a" the kns benchtest was 1200 kns for 32 bit, >> what would the 64 bit do in a similiar benchtest. >> >> > >_if_ the 64 bit program really uses 64 bit integers, then it will be faster. >Because the 64 bit processor is doing one 64 bit operation every cycle, while >the 32 bit processor will do only one 32 bit operation every cycle. The >requirement is that the program really has to use 64 bit stuff. But if it does, >a 64 bit machine is potentially twice as fast as a 32 bit machine... >That is the driving force behind 64 bit development, in fact. But in reality the 32 bit operations go at a rate of nearly 2 a cycle and on paper can get 3 a cycle versus the 64 bits we must wait and see how many a cycle can be done :) > >> >>Hammer processors, sometimes referred to as "K8," will first be produced on an >>advanced 0.13 micron SOI process out of AMD's Dresden megafab. Unlike Intel's >>Itanium, Hammer chips will provide uncompromised performance on legacy 32-bit >>applications as well as open up the 64-bit computing "new frontier." In fact, >>Hammers are expected to be the fastest chips in the world at running 32-bit x86 >>code, while seriously challenging the fastest 64-bit processors on 64-bit code. >> > > >It is unlikely they will do both well. But there are exceptions. IE if you >use single-precision floats vs double-precision floats on an IBM RS6000, you >will find _zero_ speed difference. Because the RS6000 does all FP operations >in 64 bits. So using 32 bit numbers is somewhat slower than on a real 32 bit >machine that pumps less data around. I doubt they will do this, because 'int' should go to 32 bits integers. It would mean they need a very special compiler to run normal executables on this processor in short. I think this is why the IA64 hasn't reached me yet, because i need to especially compile for it. Now that's still pretty simple as i have a cross compiler at home, so we can generate IA64 bits native code at a 32 bits machine (of course not run it). However, i doubt they will be able to do that with GCC soon. I've toyed quite some with gcc and making a cross compiler is pretty hard! I will of course not buy hammer but cross compiling an executable for it is no problem if i can get a compiler that can produce a hammer native executable. Knowing the problems of GCC just a little bit i doubt this will happen soon! Note i never managed to create at my own PC-linux machine a gcc version which could create executables for the alpha (with linux of course onboard). So that's why i still till today do not have hard numbers on how fast/slow a 21264 for me is! >>The first desktop Hammer product, the so-called "Clawhammer," will also be only >>slightly more expensive to produce than contemporary Athlons making 64-bit >>processing a real option for the masses in the near future. >> >>kburcham
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