Rebel 16.2: Impressive!

[chrisw]

Edited the text you quoted still while you already answered in red colour, to make clear even better, that I did set to 16 threads indeed, but only 8 are used by engine installed in Arena 3.5.1, even if RelaxThreadLimit true seemed to be excepted by the GUI .Engine's GUI- output about limiting to 8 cores is the same you get in console, but there 16 threads are possible to be used, as well as in Shredder- GUI, in Arena it only seems as if, yet "threads" and "cores" are mistaken by engine or by GUI obviously.

Edit- time over.
Indeed with configuring the engine's UCI- parameters once again after loading the stored setting (16 threads, RelaxThreadLimit true) by opening GUI's options and confirming them with OK), 16 threads (62% in Task-Manager) then are yet really used.
That did work three times now with GUI- restart, but only, if you don't let engine run before reopening UCI- options, if it's started in analyse- mode before you reconfigure it, you have to unload and reload the engine again, before you reconfigure its UCI- parameters. Otherwise only 8 threads are used again, if 16 are set (and 32 should be possible)

This is clearly an Arena issue. There are plenty of other GIU's to use.

[carldaman]

I can confirm that the Shedder 13 GUI allows 4 core usage after setting RelaxThreadLimit=true in the eng options!

However, the same fix did not work with Chessbase. Only 2 cores used by CB/Fritz even after adding the command to the uci file.
Has anyone else tried using CSTal with Chessbase or Fritz? It may be buggy, just like Arena...

[peter]

I can confirm that the Shedder 13 GUI allows 4 core usage after setting RelaxThreadLimit=true in the eng options!

However, the same fix did not work with Chessbase. Only 2 cores used by CB/Fritz even after adding the command to the uci file.
Has anyone else tried using CSTal with Chessbase or Fritz? It may be buggy, just like Arena...

Fritz doesn't work with RelaxThreadLimit, at least not in the ways I tried to store the command in .uci- file. Didn't find any way to make CSTal use more then 8 threads (4 cores) of the 16-core CPU with hyperthreading on in Fritz(18)- GUI, same 33% performance in Task- Manager as without RelaxThreadLimit in console. In Fritz it's even worse then in Arena or Shredder, because no message is given in output, that only 8 threads are accepted (no "limiting Threads to x cores"), 16 and 32 can be set and are falsely shown as used without any influence to CPU- performance.

In Banksia you'd probably have to edit the json- file of the engine, which I haven't done so far.

Did you try my workaround for Arena, I desrcribed here?

[carldaman]

I tried your workaround for Arena, but it keeps reverting to 2 cores no matter what.
Since the difference between 2 and 4 cores for a nnue engine is not earth shattering
I'll probably leave it at that. Thanks for trying to help!

PS. It figures ChessBase would not allow a simple command to work.

[Dokterchen]

On my machine (4 cores hyperthreading off) the issue does not seem to be related to Arena, because when I start the exe directly I get:

info string Chess-System-Tal-2.00
info string Release version
info string (C) Chris Whittington 2003-2023
info string NNUE development Ed Schroeder 2023
info string ==================================

setoption name RelaxThreadLimit value true
info string set RelaxThreadLimit to value true
info string Instability Warning - at your own risk
setoption name Threads value 4
info string set Threads to 4
info string limiting Threads to 2 cores