Author: Robert Hyatt
Date: 11:55:20 03/31/03
Go up one level in this thread
The new results and old results are given below. I notice that for both,
significant performance improvement is seen until 24Mbytes of hash memory
is reached. Beyond that point, the improvement drops off even though things
_still_ see improvement with larger hash.
Again, the following notes. For 3Mbytes of hash memory, this is about 90
seconds
per move on a single 2.8ghz xeon. The dual, with 4 threads searches more than
2.0 times
that many nodes, which will probably move the break-even point up to the next
size, which
is 48M. This for a reasonable program that doesn't hash in the q-search. I'd
suspect that
for reasonable programs that _do_ hash in the q-search, the size requirement
will move up
a couple of factors of two at least, due to the overwriting that will happen.
Someone should run that test, or maybe I'll temporarily add hashing to my
q-search to
see how it affects things.
But, regardless, the hash memory for best performance is the _same_ for both
runs,
within some margin of error that is not very large. As I said, the positions
are not
important so long as they are not raw endgames like fine 70.
After vincent's test, I will give the same test but only for fine 70, searched
to a depth of
36 plies, with the same variable hash sizes. This ought to be a "best-case" for
hashing
since fine70 is about the most hash-friendly position known. This will follow a
bit
later today.
--------------------------------------
new data from Diepeveen
hash size total nodes total time
--------------------------------------
48K 685195642 10' 45.657"
96K 595795133 9' 21.891"
192K 532881448 8' 26.678"
384K 499903696 8' 7.834"
768K 464549956 7' 36.368"
1536K 419420212 6' 51.864"
3M 397280312 6' 31.477"
6M 372065936 6' 5.867"
12M 353954066 5' 49.194"
24M 335120523 5' 30.128" new "big enough" point
48M 325010936 5' 24.549"
96M 319447256 5' 22.018"
192M 316337729 5' 20.492"
384M 308363819 5' 30.439"
--------------------------------------
previous data from bt2630
hash size total nodes total time
--------------------------------------
48K bytes. 1782907232 20' 48.262"
96K bytes. 1324635441 16' 2.635"
192K bytes. 986130807 12' 4.402"
384K bytes. 654917813 8' 29.490"
768K bytes. 1867732396 22' 9.466"
1536K bytes. 1547585550 18' 36.299"
3M bytes. 1214998826 14' 47.526"
6M bytes. 997861403 12' 9.856"
12M bytes. 315862349 4' 18.384"
24M bytes. 291943247 3' 58.600" old "big enough" point
48M bytes. 281295387 3' 51.360"
96M bytes. 258749561 3' 35.094"
192M bytes. 252048149 3' 32.718"
384M bytes. 249648684 3' 36.142"
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