Author: Vincent Diepeveen
Date: 10:18:47 06/05/02
Go up one level in this thread
On June 04, 2002 at 17:52:47, Dann Corbit wrote: >On June 04, 2002 at 16:28:39, Gian-Carlo Pascutto wrote: > >>On June 04, 2002 at 16:18:55, Gian-Carlo Pascutto wrote: >> >>>Because you are using a processor that is clocked at twice the clock >>>frequency? Why compare a 1ghz processor to a (nearly) 2ghz processor >>>and conclude anything about efficiency there? Is there anything that >>>suggests that the alpha is simply more "efficient"? To justify that >>>clock frequency disparity? >>> >>>A machine twice as fast (clock freq) _should_ perform just as well as >>>a 64 bit machine at 1/2 the frequency... Less would suggest that the >>>32 bit machine simply sucks badly. >> >>I don't agree with the validity of a clock-for-clock comparison, >>but if you want to do it anyway, I'll again point to Vincent's >>numbers: >> >>At the same clockspeed, Crafty only gets 33% faster on the 64-bits >>machine. >> >>When you read this, keep in mind that most applications get _more_ >>than 33% faster on the 64-bits machine. > >All the new 64 bit chips in the discussion are pretty much beta stage right now. > >A 500 MHz 21264 hit 1M NPS for Crafty when Tim Mann did it. > >I think to extrapolate from instances has some value, but the general idea of a >64 bit chip compared to 32 has so many advantages that surely they will clobber >the 32 bit chips at some point. There will also be a point when 10 GHz 64 bit >chips are a cheap commodity item. The 32 bit chips will pretty much be >relegated to an embedded role by that time. >So, I think that architecturally, it makes good sense to design for a 64 bit >system right now. It should also operate successfully on a 32 bit system. But >sometime in the not-too-distant future, the 64 bit chips are going to blow the >doors off of the 32 bit chips and those who are not ready for the transition >will be a large step behind. That transition from 32 bits to 64 bits, for example for zobrist hashing, that work requires only 1 week or so. So if in a few years we all have cheap affordable 64 bits machine with a good compiler that can produce 64 bits code for it, we can put our hashing and a few other things in 64 bits if needed pretty much realtime then. No reason to slow down datastructures a factor 2 now. >There are several reasons that 64 bit performance data is sketchy for the new >chips. > >First, they don't want performance data out yet because it gives a good target >to the opposition. If they release it before the opposition has had time to >address it, by the time they do exceed the performance, the next generation will >be ready anyway. > >Second, as beta chips, they still have opportunities for improvements and bug >fixes. No need for any embarassing 'forgot to download the division table >completely' bugs.
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