Need a tip for 6-man syzygy ...

[Frank Quisinsky]

Hi there,

I am planning a tournament with longer time controls like
66 moves in 66 minutes + 6 sec/move; rest in 22 minutes + 2 sec/move
on a 4Ghz AMD Ryzen 9 5950X with

Now the question is
syzygy probe depth = ?
syzygy probe limit = ?

Not sure what information to give the engines?
syzygy databases are on "Samsung SSD 980 Pro 1Tb"

Maybe a syzygy expert can give me a tip?

Best
Frank

[Modern Times]

How much RAM does the machine have ? With long time controls using 6-men can see up all your available memory used up and the engine swapping to disk, because the operating system uses any free RAM to cache the tablebases. Theoretically the O/S should give that memory back when needed but I found that Windows was reluctant to do that. Linux may be better in that regard, not sure. I stick to 5-men for engine matches that I run.

[Frank Quisinsky]

Hi,

64Gb for 16-matches are still running (without ponder) to the same time.
Hash will be 512Mb ...enough for the second part of the time control ... rest in 20 minutes + 2 seconds / move.
Maybe I need 128Gb ram, I think I have to test that.

Best
Frank

[pohl4711]

Hi there,

I am planning a tournament with longer time controls like
66 moves in 66 minutes + 6 sec/move; rest in 22 minutes + 2 sec/move
on a 4Ghz AMD Ryzen 9 5950X with

Now the question is
syzygy probe depth = ?
syzygy probe limit = ?

Not sure what information to give the engines?
syzygy databases are on "Samsung SSD 980 Pro 1Tb"

Maybe a syzygy expert can give me a tip?

Best
Frank

Probe Limit means number of pieces. So, set it to 6, if you want to use the 3-6-Syzygy sets. Or set Probe Limit to 5 for 3-5-Syzygy.

Probe Depth means, the engine uses the Syszygy-Bases always (or nearly always) in its search, when it is set to 0 or 1 (depends on the engine). The higher the value of Probe Depth, the engine uses the Syzygy only in shallower search depths. Idea is, that looking in the Syzygy-bases is slower than doing an evaluation, especially, when the Syzyzgy bases are stored on a slow HDD (not SSD).
Most engines set Probe Depth to 1 per default. Your Syzygy bases are on a fast SSD, so you can use the default value 1 for Probe Depth.
In KomodoDragon, you can set Probe Depth to 0. In Stockfish not, here is 1 is the lower limt for Probe Depth...
So, my advice is to use Probe Depth 1 for all engines. Because 0 can not be used for all engines.

[pohl4711]

Hi,

64Gb for 16-matches are still running (without ponder) to the same time.
Hash will be 512Mb ...enough for the second part of the time control ... rest in 20 minutes + 2 seconds / move.
Maybe I need 128Gb ram, I think I have to test that.

???

16 matches at the same time means 32 engines in memory at the same time. 32 * 512 MB Hash = 16 GByte.
If you have 64GB Ram, you can easily switch to 1GB Hash for each engine: 32 GB for Hash are needed. Additionally, 32 engines need around 2-3 GB to store them in memory (since the nnue-networks, some engines got really huge). So, 32 engines with 1GB Hash should need around 35 GByte, not more. So, enough free memory on your 64GB-system for running windows and for caching the Syzygy bases. And with such long time-controls, I strongly recommend to use at least 1GB Hash for each engine!!! (Mention, 1GB Hash means (around) 100 million positions can be stored in the hash-memory and 100 million positions are not very much, when engines are running fast and with long time controls.)

For comparison: I use 256 MByte Hash for my testings for my UHO-Top15 ratinglist. And in there, the engines are running with a short time-control (3min+1sec) and not very fast, because I run 20 games on my 12core AMD Ryzen CPU...
On my machine, 17 GByte are needed (used), when the tests are running: 20 games = 40 engines in memory. 40 * 256 MB Hash = 10 GByte. And 40 engines in memory. And Windows running. (7 GB alltogether).

[Frank Quisinsky]

Hi Stefan,

thinking that for the endgame ... Rest in 20 + 2 seconds/move engines don't need more hash as 512Mb.
More hashtables will not produce a weaker final results and a lot of engines are "hh" hash-hungry.

I will give 1Gb for hash!

Thanks for your explanation to syzygybases.
I will check the settings for all the participanting engines can use syzygybases.

If you have time ...
I had a special question for you in your Crystal thread (tournament selection).

Have a nice weekend!

Best
Frank

[Ajedrecista]

Hello Stefan:

Probe Limit means number of pieces. So, set it to 6, if you want to use the 3-6-Syzygy sets. Or set Probe Limit to 5 for 3-5-Syzygy.

Probe Depth means, the engine uses the Syszygy-Bases always (or nearly always) in its search, when it is set to 0 or 1 (depends on the engine). The higher the value of Probe Depth, the engine uses the Syzygy only in shallower search depths. Idea is, that looking in the Syzygy-bases is slower than doing an evaluation, especially, when the Syzyzgy bases are stored on a slow HDD (not SSD).
Most engines set Probe Depth to 1 per default. Your Syzygy bases are on a fast SSD, so you can use the default value 1 for Probe Depth.
In KomodoDragon, you can set Probe Depth to 0. In Stockfish not, here is 1 is the lower limt for Probe Depth...
So, my advice is to use Probe Depth 1 for all engines. Because 0 can not be used for all engines.

Thank you very much! I did not know about the correct settings of these parameters, thus always set as default. Since I only have got up to 5-man Syzygy EGTB, the default value of SyzygyProbeDepth = 7 in SF 16 (and former versions of SF) was senseless for my setup. I have been wrong for years!

Regards from Spain.

Ajedrecista.