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What is this CCC3 threads thing now?

Posted: Sun Jan 06, 2019 8:51 pm
by Jouni
Houdini 6.03 (64 threads, 16 GB hash)
Komodo 2242 (46 threads, 6 GB hash)
Stockfish 19010616 (90 threads, 16 GB hash)

SF is too weak and get more power :?:

Re: What is this CCC3 threads thing now?

Posted: Sun Jan 06, 2019 9:16 pm
by Paloma
No, i think programmers don't dare to set threads higher (stability problem) :)

Re: What is this CCC3 threads thing now?

Posted: Mon Jan 07, 2019 2:51 am
by arunsoorya1309
We moved to Linux and wine does not support more than 64 threads. So Houdini is 64 threads

As for komodo, Mark and Larry wanted it, i cannot disclose why they wanted it. They can clarify if required

Re: What is this CCC3 threads thing now?

Posted: Mon Jan 07, 2019 5:00 am
by Modern Times
arunsoorya1309 wrote:
Mon Jan 07, 2019 2:51 am
We moved to Linux and wine does not support more than 64 threads.
I take it that you didn't know that beforehand ?

Re: What is this CCC3 threads thing now?

Posted: Mon Jan 07, 2019 6:51 pm
by lkaufman
Jouni wrote:
Sun Jan 06, 2019 8:51 pm
Houdini 6.03 (64 threads, 16 GB hash)
Komodo 2242 (46 threads, 6 GB hash)
Stockfish 19010616 (90 threads, 16 GB hash)

SF is too weak and get more power :?:

Since the machine has 48 cores, we don't believe it is helpful for Komodo to use more than that number of threads (minus 1 or 2 for other things the computer does). Kai showed that it probably helps to use more than four threads on a four core machine, but it is unlikely to help on one with many cores since the benefit is much smaller while the cost (in speed per thread) is not. Actual tests show no meaningful elo difference for using extra threads beyond cores on a 32 core machine. With Komodo MCTS, it is definitely bad to use these extra "threads". Maybe Stockfish and other engines get some benefit from using more threads than cores, but I doubt it.

Re: What is this CCC3 threads thing now?

Posted: Mon Jan 07, 2019 9:45 pm
by Jouni
Thanks for explanation. But how do You know, that Komodo then uses real cores and no virtual ones, if computer has HT on?

Re: What is this CCC3 threads thing now?

Posted: Mon Jan 07, 2019 10:11 pm
by zullil
Jouni wrote:
Mon Jan 07, 2019 9:45 pm
Thanks for explanation. But how do You know, that Komodo then uses real cores and no virtual ones, if computer has HT on?
Only a very stupid OS would schedule two threads onto the same physical core, assuming almost all the physical cores are available.

Re: What is this CCC3 threads thing now?

Posted: Mon Jan 07, 2019 10:23 pm
by lkaufman
Jouni wrote:
Mon Jan 07, 2019 9:45 pm
Thanks for explanation. But how do You know, that Komodo then uses real cores and no virtual ones, if computer has HT on?
It seems that the truth is somewhere between these two extreme possibilities. When the thread count goes beyond the core count, total NPS continues to climb, but nps per thread drops more rapidly than total NPS climbs. I'm not enough of a hardware expert to explain just why this is so, but perhaps with the lower thread count it tries to do one core per thread but is not always able to do so for technical reasons. It may well be that using 63 or 64 threads (out of 88 or 96 on a 44 or 48 core machine) may be slightly better for most engines than using either (cores-1) or (2*cores -2); my own tests on a 32 core machine showed roughly a tie score between using 31 or 47 threads for normal Komodo; for Komodo MCTS it is definitely bad to use more threads than cores on big machines.

Re: What is this CCC3 threads thing now?

Posted: Sat Jan 12, 2019 11:08 pm
by Jesse Gersenson
[want to delete my post]...

Re: What is this CCC3 threads thing now?

Posted: Sun Jan 13, 2019 6:39 am
by glennsamuel32
zullil wrote:
Mon Jan 07, 2019 10:11 pm
Jouni wrote:
Mon Jan 07, 2019 9:45 pm
Thanks for explanation. But how do You know, that Komodo then uses real cores and no virtual ones, if computer has HT on?
Only a very stupid OS would schedule two threads onto the same physical core, assuming almost all the physical cores are available.
On my laptop, HT cannot be disabled.
So Win10 shows 8 cores,whatever I do.
If I choose any engine to use 4 "real" cores, it runs at 50%.
Only if HT can be disabled in the BIOS, can you allot actual cores.