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Up Topic Rybka Support & Discussion / Rybka Discussion / Pseudo Core Problem? Maximum "Effective" Processor Config?
- - By PiPhD Date 2009-11-10 23:32
I have recently become aware that some multi-core computers have what is called a "pseudo" core where the second core of a core 2 duo for example is not utilized by deep chess software.  That in a quad core potentially 2 of the cores are unused.  It also appears that a 16-core machine may actually be slower than a quad that utilizes all four cores due to reduced efficiency of managing 16 cores in tandem.

In your opinion, what is the best hardware manufacturer and configuration to optimize Deep Rybka's playing ability while understanding the pseudo core issue?  What is the best configuration where ALL of the cores are used at the fastest speed possible without water cooling or overclocking?

All links and information are greatly appreciated!

Thanks!

- pi -
Parent - - By Fulcrum2000 (****) Date 2009-11-11 11:12
You are talking about CPU's with Hyper Threading (HT). Those HT threads are indeed not optimally used by multi-processor/core versions of chess programs. A native quad core like the Q6600 has 4 "good" threads and will function as expected, others like the core i7 processor has 4 real cores and 4 'pseudo' cores. To get optimal results from this processor for chess you should disable the hyperthreading (in the BIOS).
Parent - - By Martin Hander (*) Date 2009-11-11 19:21
Why is disabling hyperthreading better than just setting the UCI parameter "Max CPUs" to 4, so that Rybka uses only 4 processes?
I asked this question some time ago, but I got zero replies.
Parent - By Vempele (Silver) Date 2009-11-11 19:39
See the "confused about kn/s" thread.
Parent - - By Fulcrum2000 (****) Date 2009-11-11 20:26
The Operating System has a problem distinguishing between real and virtual cores, so 2 threads might still be 'booked' on the same core. I hear reports the Windows & scheduling is better (didn't try myself yet).
Parent - By Fulcrum2000 (****) Date 2009-11-12 19:14
Windows & = Windows 7   ;-)
Parent - - By PiPhD Date 2009-11-12 00:28 Edited 2009-11-12 00:31
While I do appreciate the information at this link regarding "confused about kn/s"...

http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=13311

I am more interested in the most powerful specific computer configuration where Rybka can actually take advantage of the real cores.  Is there a particular manufacturer that delivers the most complete configuration without needing to customize it very much?

Thanks,

- pi -

P.S.  Is there a UNIX system that is better than a Windows system as far as Rybka is concerned? 

P.P.S.  Is there a particular version of Windows that is better than the others for Rybka?

P.P.P.S.  Will Rybka 4 address the virtual core issue without needing to configure the bios?
Parent - By Jarman (*) Date 2009-11-12 19:30
I share the same interest. On a side note, having a topped thread about how to properly configure your system for optimal performance would be great after Rybka 4 is released.
Up Topic Rybka Support & Discussion / Rybka Discussion / Pseudo Core Problem? Maximum "Effective" Processor Config?

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