Syzygy on RAM Drive

[Laskos]

I'm not in any way in competition with Eugene Nalimov. The concept of "fairness" seems to be foreign to the present topic.

I am not talking that you personally are in competition with someone, but an engine using Syzygy might be in direct competition with an engine using Nalimov, and if one consumes GBs of RAM freely, then allow the other engine, for example, to use more Hash. There is resources competition.

If you have (literally) more than enough RAM then sure, but in general no. Nalimov files are also cached in the page cache (and then separately decompressed in the engine's TB cache). Loading them on RAM disk will help during the first accesses (it will not take much time to copy some relevant parts from RAM disk into the page cache) but not in the long run (RAM available for the page cache will be much smaller).

I just did a partially conclusive test with Komodo 7a which shows that Syzygy on RAMDisk are a bit better than on HDD.

1/ Direct match K7a Syzygy RAM against K7a Syzygy HDD, partly conclusive:

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1'+1'' on one core
MES400.epd endgame suite
 1.  K7a Syzygy RAM           	515.0/1000	310-280-410
 2.  K7a Syzygy HDD           	415.0/1000	280-510-410

2/ K7a test on MES400.epd endgame suite for solutions and time, 5s per position:

Code: Select all

Syzygy RAM: 373/400 3:12
Syzygy HDD: 364/400 4:04 

That's a bit more conclusive.

[yurikvelo]

If you don't use a RAM disk, upon access the relevant parts of the TB files will be cached into RAM anyway in an area called the "page cache". Once certain data is in the page cache it will stay there even between engine restarts, unless the OS needs the RAM for something else.

This is done DURING game.
When you use RamDisk you perform this costly operation BEFORE game starts.

[bob]

If you don't use a RAM disk, upon access the relevant parts of the TB files will be cached into RAM anyway in an area called the "page cache". Once certain data is in the page cache it will stay there even between engine restarts, unless the OS needs the RAM for something else.

This is done DURING game.
When you use RamDisk you perform this costly operation BEFORE game starts.

He explained the solution. cat <files> >/dev/null and everything is cached BEFORE you start a game. I've done this for years when using Nalimov in fact..

[yorkman]

Is it possible to store my 3 syzygy paths in ram on Windows, such as Win'2012 R2? I'm currently using Syzygy from SSD.

If it's possible, how do I do it? If it matters my gui is Aquarium.

[mwyoung]

RAM disks not worth it...SSDs are a much better option.

I find it better also to store the data on a fast SSD. Even with 6 man table base, and probe depth set to 0 running 32 threads. I get no slow down when testing the engines.

[Eduard]

SSD of course. I also play with 7 men. Runs well on SSD. HDD is not good enough.

[mwyoung]

SSD of course. I also play with 7 men. Runs well on SSD. HDD is not good enough.

Yes HDD are awful, but if you are strapped for cash. I have even put Syzygy on a thumb drive and it works...

[MikeB]

Is it possible to store my 3 syzygy paths in ram on Windows, such as Win'2012 R2? I'm currently using Syzygy from SSD.

If it's possible, how do I do it? If it matters my gui is Aquarium.

it can be done, but one has to consider how much RAM they have. 6 man syzygy takes 195GB , so if you have 512GB of ram , no problem. If you have 16Gb RAM , just let the OS take care of it.

PS the long hyphen is now the new nine on this board.

[Raphexon]

SSD of course. I also play with 7 men. Runs well on SSD. HDD is not good enough.

Yes HDD are awful, but if you are strapped for cash. I have even put Syzygy on a thumb drive and it works...

HDDs aren't a cost-effective long term solution if you do a lot of analysis or do a lot of computer tournaments because the constant reads will kill that HDD.
Especially 7 man TBs will chew that thing up.

[Zenmastur]

On a 1GB RAMDisk I put the 5-men Syzygy (both WDL and DTZ), and let the top engines play with and without Syzygy at 1' + 1'', on one core. Balanced endgame positions up to 12 men (had to suffer many draws with these balanced endgame positions).

…snip...

Within error margins, but it seems that SF (Ronald's 22.05 build) gains more from Syzygy than the other two.

It's an interesting test I'm just not sure I see a lot of use for this using 5 man TB. At very short time control it may help but at longer time control do 5-man TB's actual increase ELO or save any time vice no TB's?

One thing I would be interested in is the difference in maximum probe rate of a ramdisk vs SSD vs HDD as the core count increases from 1 to X. This clearly depends on the speed the cores are running at but most modern CPU's run between 3.5 Ghz and 4.0 Ghz stock. I'm sure at some point, with enough cores probing the TB an SSD will become read saturated. It would be interesting to know about how many cores at what core speed is required to do this on an “average” SSD.

Regards,

Zenmastur