Author: Robert Hyatt
Date: 14:28:33 08/25/03
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On August 25, 2003 at 16:28:31, Sune Fischer wrote: >On August 25, 2003 at 16:17:34, Dan Andersson wrote: > >> I would rather have 2.4 MNps on a single CPU :) And a single agent search will >>be more efficient except special cases. A pardox is that larger cache can be >>counter productive for some parallel applications due to increased memory >>traffic. > >Yes, but this memory trafic is a different animal than what the thread was >talking about. > >The tread was about making/uncopying, and for that you don't need inter chip >communication, each thread can run independently and can uncopy independently on >its own stack. For this double cache bandwidth is good, two chips can simply >copy double as fast as one chips so Bob's argument that 2.4 Mnps was more than >twice as bad 1 Mnps isn't valid concerning this specific issue. That is simply incorrect. Whether you have a dual or a single, if you run at 2.4M nodes per second you have a definite cache bandwidth requirement, and a definite memory bandwidth requirement, for my particular program, running at that particular NPS. IE if I can run at 2.4M nodes per second on a _single_ CPU, I _still_ have to copy _exactly_ the same number of bytes per node per copy/make. If I do them 1/2 as fast, but do them twice on two processors at the same time does not matter. The total bandwidth to support 2.4M nodes per second is a fixed number whether I do it with 1 processor or 1024. > >I realize there are many other factors pointing in the negative direction (e.g. >copying the stack itself between chips would be a killer). > >-S. > >>MvH Dan Andersson
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