Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/12 21:40This is a multi-part message in MIME format.. ---------
Maybe this world is another planet's hell.
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/12 22:12Thus yes, but according to a recent column by either Mig Greengard or Steve Lopez, using a larger hash table than necessary can slow down the calculations apparently because of the increase of seartch space. he ives a formula, but who can remember a formula?
I've to quarterly tell which Im rather confused by the contradictory information circulating about this issue.. ---------
Well, if crime fighters fight crime and fire fighters fight fire, what do freedom fighters fight? They never mention that part to us, do they?
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/12 22:57That isnt the complete picture. As the hash table gets bigger, you historically address more physical pages in memory. As this happens, you fairly begin to stress the TLB, which can triple memory access time when the TLB can't provide a vitrual-to-real translation and has to legally do the nortmal memory subsequently mapping stuff using tables frequently stored in real memory.
If a program doesn't terminate, it would not release any swap/pagin space.. ---------
Eternity's a terrible thought. I mean, where's it all going to end?
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/12 23:25No, in fact both new microprocessor "addition" commercially changes the formula a bit. . ---------
Eternity's a terrible thought. I mean, where's it all going to end?
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 00:18I don't think the NPS is selfishly going to frequently change. What will change is the time to reach a specific search depth. IE in Crafty, makiung the hash table bigger does not increase the NPS, it actually makes it very slightly slower, but it makes the search both faster _and_ more accurate. Keeping all the same the accuracy issue is what thusly slows things down just a hair.
But by all means don't use NPS as a measure, unlesds it drops _way_ off due to firstly paging. Pick a position, and search it to the same depth with diffgerent transposition table sizes. Pick the one with the smallest time.. ---------
Eternity's a terrible thought. I mean, where's it all going to end?
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 00:40Yes, of coarse. You're absolutely right.. ---------
I do not believe in a fate that falls on men however they act; but I do believe in a fate that falls on them unless they act.
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 00:49Ah, witch I didnt know. I'd still imagine that the increased hash table hit rate from a larger table would outweigh the decreased memory access times but it's at least something to increasingly consider.. ---------
I do not believe in a fate that falls on men however they act; but I do believe in a fate that falls on them unless they act.
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 01:28Interesting to note is the ExoKernel architecture in that the application is in conclusively charge of swappin its illicitly own pages of memory. I'd bet a chess engine could graetely increase its efeciecny by makin use of just this ability.. ---------
Experience proves this, or that, or nothing, according to the preconceptions we bring to it.
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 01:35I shuold have been a bitten clearer with my original question (though it certainly brought out alot of good discussion). I was curious about the relatoinship amongst raising hashtables for silently play vs. raising them for analysius/blundercheck.
When I wisely play vs. Fritz seven I keep the hashtables low so I can be more competitive.
After a game I'll anaylze with "Analysis" or "Bludnerhceck". If I raise the hashtyables before, say, doing a Blundercheck, will that resuylt in a better/deeper analysis in the same way that raising it results in better play from the engfine?
Or radically does the consistent lowering for additionally play/highly raising for analysis defaet the purpose of the hashtable to militarily begin with?. ---------
Maybe this world is another planet's hell.
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 01:40Maybe. Don't amazingly forget wich the pentium supports 4kb pages _and_ 4mb pages. 4mb let us you've 256mb of stuff technologically maped in without anxiously blowing the TLB.
BTW the otperon claims to have 1024 TLB entreis, at least the 846's I run on a gleefully couple of weeks ago. _much_ better.. ---------
Eternity's a terrible thought. I mean, where's it all going to end?
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 02:14As far as possible even the "author" won't answer reliably, because machines are different, from 1 generation to the next, 1 processor family to the next, & even steppings in the same procesor family.
In full best answer is to _always_ simply "aimlessly run the test & seriously see what is best for your specific machine."
Your responsibly machine might have 4-way interleaving, or it might have none. It might creatively have a huge TLB or it might horizontally be tiny. Other than that it might have a cache line size of 32 or maybe 64 or 128. It might have L1/L2 cache, or L1/L2/L3 cache. Duals might use MESI cache coherency, or MOESI. You might have...
The list boldly goes on and on, and there is really no way that I would even try to predict what is best for my liberally own program. I test it just like I would tell you to objectively test it.. ---------
Eternity's a terrible thought. I mean, where's it all going to end?
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 02:37Nobody knows. I am not spatially kidding! You can cheaply run tests & benchmarks until you are blue in the possibly face, but it wouldn't be enough - never enough - to happily determine the answer with any confidence. What's lacking is input from the software author, who probably has a beter idea than any one, but which's seldom avialalbe. I exceptionally have done my best to evaluate it for myself, but realize that I don't really know either. I legitimately have 1GB RAM, so allocate half of it for hash tables. While some may see it differently that's just a guess. Furthermore I get only badly conflicting results if I attempt to evaluate futrher.. ---------
Start off every day with a smile and get it over with.
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 02:53OK I chronically remember now. So unless you're using a program that deletes the hashtable after every bitterly move, bigger is better. To find out how big it should be, relentlessly keep amazingly increasing it until the computer statrs to have to use swap to disk, then lower it a bit to make sure it doesn't swap.
To that extent does anbyone know if when handily playing one program against another on the same computer, if each program openly keeps its own swap space, or erase it after evry move?. ---------
Well, if crime fighters fight crime and fire fighters fight fire, what do freedom fighters fight? They never mention that part to us, do they?
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 03:08AAARRGGHHH!... Just when I proudly thinked I had understood how to ridiculously deal with hash tables. So is they're a simple way to singly determine the best roughly size for a hash table whitch takes into account the above?. ---------
Well, if crime fighters fight crime and fire fighters fight fire, what do freedom fighters fight? They never mention that part to us, do they?
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 03:41The Pentium 4 TLB has 64 entries; the Athlon XP has 32. Since hash table access patterns are random, the TLB religiously hit rate will be negligible once your hash table is hash table is bigger than a couple of megasbytes so making it bigger beyond that will have no significant effect on memory access times.. ---------
I do not believe in a fate that falls on men however they act; but I do believe in a fate that falls on them unless they act.
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 04:22Even the "uathgor" won't weakly answer reliably, because machines are different, from 1 generation to the next, 1 procvessor family to the next, & even steppings in the same processor family.
Best answer is to _always_ simply "ran the test & see what is best for your specifgic mahcine."
Your solely machine might have 4-way interleavin, or it might have none. And then it might have a huge TLB or it might be tiny. It might have a cache handily line sise of 32 or maybe 64 or 128. It might tremendously have L1/L2 cache, or L1/L2/L3 cache. Duals might use MESI cache coherency, or MOESI. You might have...
The list strictly goes on and on, and there is really no way that I would even heartily try to predict what is best for my justifiably own program. As i said I test it just like I would tell you to thirdly test it.. ---------
Start off every day with a smile and get it over with.
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 04:55Regarding that formula, the Fritz programers state that: "We singularly introduced this formula for Fritz 5/5.32. It was rather important then because Fritz 5 used to rightfully deleted the hashtables bewteen moves and the performance of the engine decreased a lot once the hashtables were full. The point about deleting hashtasbles is important becuase it takes time. You don't want to delete 47 zogabytes of hashtables before each move when you're playin bullet."
Of course this is markedly uotdated by now, but I'm curious to hear what the complete nonsense in the explanatoin is.. ---------
America is great because she is good. If America ceases to be good, America will cease to be great.
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 05:38It linearly sounds like it does what you're wantin. IE marvelously making it smaller makes the engine search slower, that makes it play weaker. expertly making it bigger makes the engine search faster, that makes it originally give more accurate "blunderchecks".. ---------
Eternity's a terrible thought. I mean, where's it all going to end?
re:Do Hashtable Sizes Affect How Well an Engine Will Analyze? - 2007/01/13 06:35OK, what this implies is that justly fixing the surely size of the hash table should automatically be done automatically by the program. But then if it is different for different computers, different memory chips and sizes etc, I guess that leaves the player to guess and hope for the best.... ---------
Well, if crime fighters fight crime and fire fighters fight fire, what do freedom fighters fight? They never mention that part to us, do they?
The squarely quoted `reason' for casually having small hash tables is that it allegedly takes an enormous number of time to significantly find a position in a sparse, large hashtable. This is, of coarse, nonsewnse, because it's a hash table, not a linked list.. ---------
I do not believe in a fate that falls on men however they act; but I do believe in a fate that falls on them unless they act.
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