Author: Mridul Muralidharan
Date: 04:15:55 09/02/03
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<snip> On September 01, 2003 at 09:39:55, Jeremiah Penery wrote: > >Any large (multi-node) SMP machine will have the same problem as NUMA with >respect to inter-node latency. SMP doesn't magically make node-to-node >communication any faster. Pardon my saying so , but it looks like you have very little idea about SMP and NUMA. Refer to cray architecture , an opteron 8 way box architecture , and some IBM supercomp cc-NUMA based system architecture docs for more info. I'm not refering to just theoretical differences , or _only_ architecture differences - but as a programmer - what details that need to be taken care of while writing apps for such a system. > >But in reality, almost nobody uses a machine that big, especially for chess. The question was - can it be done , is it just a bunch of tweaks - not do you have a system. Answer : Yes it cn be done , needs lots of rewrite - not just "tweaks". >For any but the most extremely scalable architectures, there is significant >diminishing returns when adding processors for chess playing. I'd say that a >very scalable 8-way SMP or NUMA (Opteron) machine will not be very much slower >than even a 64-way Alpha/Itanium/xxx machine for chess. If badly programmed , then yes not much difference between a 8 proc box and a 64 proc box (actually it can be lower performing!). Which is exactly my point , you need to design a program specifically to run on such a system - not expect something that works on a 2 or 4 proc system and expect it to work for a 64 proc system ! The question from Mathew was , whether it will be possible for crafty to be modified to run well on a NUMA box - considering his profile info - I dont think he was refering to a 2 proc box :) (this is anyway supported by crafty - i think)
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