how to use Glaurung with 8 CPU ??

[Daniel Charles]

Dear Tord ,

Do you know how I could play with Glaurung epsilon using 8 cpu on Fritz GUI ?
UCI Option stop at 4 CPU

Or if anyone knows the answer (fell free to help )


Thanks

Daniel

[Dann Corbit]

I think you may have to recompile it.
I guess that maximum CPUs is a compile time constant.

[NowCan]

Yes.
In glaurung.h


// Comment out the following line for a single-threaded executable:
#define SMP

#if defined(SMP)
const int MaxNumOfThreads = 4;
#else
const int MaxNumOfThreads = 1;
#endif

[Volker Pittlik]

Yes.
In glaurung.h

This is only true for older versions. In Glaurung 2 e/5

a) there is no glaurung.h
b) the maximum number of threads is just an UCI option

// Comment out the following line for a single-threaded executable:
#define SMP

#if defined(SMP)
const int MaxNumOfThreads = 4;
...

Please notice that

Code: Select all

volker@vpittlik:~/schach/glaurung/g2e5/src> ./glaurung2-e5
uci
id name Glaurung 2-epsilon/5
...
option name Threads type spin default 1 min 1 max 4
uciok

The max number of threads is 4. Therefore I think it seems impossible to use 8 CPUs, but please correct me if I'm wrong.

Volker

[Tord Romstad]

Hi all,

It's better to direct technical questions about Glaurung to the Winboard forum. Computer chess has very low priority for me at the moment, and I don't follow the discussions on the CCC very carefully. I was lucky to spot this thread.

Please notice that

Code: Select all

volker@vpittlik:~/schach/glaurung/g2e5/src> ./glaurung2-e5
uci
id name Glaurung 2-epsilon/5
...
option name Threads type spin default 1 min 1 max 4
uciok

The max number of threads is 4. Therefore I think it seems impossible to use 8 CPUs, but please correct me if I'm wrong.

You are right, without changing the source code, the maximum number of threads in Glaurung 2 - ε/5 is 4. This limit can be changed by editing the constant THREAD_MAX in thread.h. However, I don't think doing so would improve the speed of the program on a computer with 8 CPUs. Glaurung 1.2.1 is only very slightly faster with 6 threads than with 4 threads, and with 8 threads it is actually a tiny bit slower than with 4 threads. I expect Glaurung 2 - ε/5 to behave similarly in this respect.

I have some hope that Glaurung 2.0 (which is almost ready) will scale somewhat better to computers with many CPUs, but because I have no computer with more than 2 CPUs for my own testing and development, it is hard to be sure.

Tord

[Volker Pittlik]

It's better to direct technical questions about Glaurung to the Winboard forum...

Yes! Please do so as Tord has written!

(Insert random number of stupid smilies here: .>....<)

Volker

[BBauer]

I could do some test using 4 threads on a Xeon box running at 3GHz with some memory, up to 16 Gb.

BTW, yesterday I could not find your homepage.

best wishes
Bernhard

[Tony Thomas]

Yes! Please do so as Tord has written!



Volker