Author: Tom Kerrigan
Date: 19:51:25 02/09/03
Go up one level in this thread
On February 09, 2003 at 21:41:08, Russell Reagan wrote: >Perhaps the questions I ask are only asked out of ignorance, but how can the >hash table be considered to be used "infrequently"? Also, if you look at a If a program does a hash lookup at every node, that's a couple of memory accesses per couple thousand instructions. If hash lookups aren't done in the quiescence search, you could go for tens (possibly hundreds?) of thousands of instructions per memory access. That's not frequent access. >program like Crafty, it makes use of lookup tables that exceed 256kb of memory >that are used at every node (until captures). Why is this not considered to be >in the program's "working set"? First, because it's a lookup table, you only want a few bytes from the table, not the entire 256+ KB. Second, you may _never_ need to access some (or most) of the table. Third, if the table isn't accessed in the quiescence search, again, you can go for tens of thousands of instructions without accessing it. Just to give you an idea of working sets and how much data is acutally used most of the time by chess programs, consider TSCP. It has over 40K of tables and its executable is 150K, yet it scales perfectly with clock speed on the original Pentium. That means its working set is less than 8K for code and 8K for data. -Tom
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