Author: Don Dailey
Date: 13:56:06 05/29/98
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On May 28, 1998 at 16:02:52, Georg Langrath wrote: >I have just bought Fritz5, and I am very satisfied with it. But there is >a disadvantage with it that everybody that want to buy it should be >aware of. It is enormously memoryhungry. In the manual they recommend 72 >MB! memory for a Pentium 200 in average 3-minutes play. And it is so. >When the beast has eaten the hashmemory it nearly stops analyzing. To >analyze longer time for example 15 minutes is impossible for usual >homecomputers. >I myself always play on shorter time, so my memory is enough (32MB on >Pentum133). But if I should like to play tournament level I had to >upgrade. The formula according to manual is 2 x HZ x minutes. > >Georg I've read all the responses to this post and am surprised by some of them. I think I will try to clarify some of the myths. 1. Bigger hash tables sometimes makes the program slower. There are only 2 reasons this happens sometimes. Extra memory can reduce cache hits a little, not a very large effect. The seond thing that can happen is the search will change a little with any hash table size change. This is quite normal. The effect will occasionally and randomly make a bigger hash table look at more nodes. But ON THE AVERAGE having bigger hash tables will reduce the node counts. To test these things do not run 1 position, but run several and average them together. 2. At some point bigger hash tables don't seem to help. This is true, if you don't run deeper searches. If the hash tables do not get filled up, making them bigger is unlikely to help much if any (but it won't hurt either.) Bigger hash tables (on the average) will ALWAYS help if you run a position long enough. 3. Fritz stops searching if the hash tables are too small. This is completely ridiculous. What we see is that Fritz saturates its hash tables more quickly than most if not all the other chess programs. When this happens there is a larger multiplier going from one iteration to the next. This happens for all chess programs, but Fritz is so fast it gets to this point sooner. This should be considered a GREAT thing, not a BAD thing. It's just more proof that Fritz is faster than the other chess programs. From a human subjective point of view, all programs seem to bog down when they've been thinking a minute or so. This is mainly just our own perception or impatience. We think, gee it got up to 10 ply in just a few seconds or so but it's taking forever to get up to 12. This effect may seem bigger on Fritz which gets up there really quickly. - Don
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