GPU chess update, local memory....

[smatovic]

recently i was convinced that by the use of local memory (memory shared by all items of an work-group resp. thread block)
and by coupling single threads (64) to work on the same chess position a fast but simple engine could be implemented.

in practice two issues hampered this idea:

1) Benchmarks showed that i will have to run multiple work-groups to utilize the gpu.
But by running multiple work-goups the local memory per work-group would not be enough to store a move-list-stack and additional search tree information.

2) Coupling threads to work on the same chess position in parallel is possible, but as son as i wish to sync the work, or share information between the the threads i loose a lot of cycles, so a "one thread one board" approach looks more promising.

--
Srdja

[smatovic]

Playing around with local atomic functions,

get about 50 Knps to 100 Knps per work-group (running 64 threads) for an vanilla alphabeta implementation.

Hope i can quadruple the nps and then try a lazy smp approach with up to 512 work-groups...

--
Srdja

[bhamadicharef]

Maybe this can be of help

Design patterns for GPU computing
http://nvlabs.github.io/moderngpu/

[smatovic]

thx, any help is appreciated.

--
Srdja

[Dann Corbit]

51M NPS would raise some eyebrows. I guess it would become the world's most cost effective chess engine (in terms of nodes per dollar).

[Dann Corbit]

This looks interesting:
https://github.com/GPUOpen-Professional ... -Tools/HIP

It is a toolset that works on open CL and cuda and includes atomics.

[smatovic]

It is a toolset that works on open CL and cuda and includes atomics.

Thanks, i will take a look into it.

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Srdja

[smatovic]

Hmm, it seems not to pay off,

i stuck on 40 Knps (on AMD HD 7750) to 100 Knps (on Nvidia GTX 750) for an single work-group running 64 threads.

And it looks like register usage prevents to run the gpu under full load,
so i end up with 1.5 Mnps with 64 work-groups on the AMD HD 7750 and 2 Mnps with 32 work-groups for the Nvidia GTX 750.

Maybe someone smarter than me can squeeze more juice out of it...
anyway here is the code:

https://github.com/smatovic/Zeta/tree/v099a

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Srdja

*** edit ***

PS: parallel search is yet not implemented

[Dann Corbit]

I have an AMD GPU card on this machine.
When I ran with --guessconfig it configured itself for the I-7 CPU.
How do I tell it to examine the GPU?

I have AMD Radeon 6900 series with 2 GB GPU RAM.

[Dann Corbit]

Graphics Card Manufacturer - Powered by AMD
Graphics Chipset - AMD Radeon HD 6900 Series
Device ID - 6719
Vendor ID - 1002
SubSystem ID - 3121
SubSystem Vendor ID - 1682
Revision ID - 00
Bus Type - PCI Express 2.0
Current Bus Settings - PCI Express 2.0 x8
BIOS Version - 013.010.000.007
BIOS Part Number - 113-695CDF80-113-C2050200-100
BIOS Date - 2011/01/06 03:01
Memory Size - 2048 MB
Memory Type - GDDR5
Memory Clock - 1250 MHz
Core Clock - 800 MHz
Total Memory Bandwidth - 160 GByte/s
2D Driver File Path - /REGISTRY/MACHINE/SYSTEM/ControlSet001/Control/Class/{4d36e968-e325-11ce-bfc1-08002be10318}/0000