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Up Topic The Rybka Lounge / Computer Chess / Hyperthreading Results (Clemens Keck)
- - By BrandonSi (***) Date 2010-02-22 20:52
Not sure if anyone else is following this, but I have been watching closely. I've always thought that at the very least HT should result in a negligible loss of performance with regards to chess engines, and should, in most cases, result in an increase in performance. Granted, many chess engines implement SMP/MP differently, so results vary with the engine. Clemens Keck has been testing this theory since the beginning of February and has had some interesting results.

The original link is below (German).

I'll summarize in English, but you can also read the translated (Google) text with the link below.

Deep Fritz 11 gets +28 elo with HT=ON.
(Deep) Rybka 3 gets +/- 0 with HT=ON/OFF.

Currently Deep Shredder 12 is under testing.

All these tests are done with an i7 920, so disregard this information as it may apply to the previous generation of HT that was available with the P4.

Translated link -

Parent - - By Fulcrum2000 (****) Date 2010-02-22 21:10
I couldn't find one important fact. Did he test HT off by reducing the numbers of cores in the engine to 4 or by turning HT off in the BIOS?. It might be a big difference.
Parent - By BrandonSi (***) Date 2010-02-22 21:19
I would imagine he turned it off in the bios. I would not consider it a valid test if he manually specified processor affinity.
Parent - - By M ANSARI (*****) Date 2010-02-22 21:19
HT is also OS dependent.  Win 7 OS handles virtual cores and logical cores much better than other OS's and I would not expect there to be any loss of strength.
Parent - By BrandonSi (***) Date 2010-02-22 21:22
Certainly a valid point.
Parent - - By Vempele (Silver) Date 2010-02-22 21:25
Wrong. Linux got it right on the first try, and Lukas has posted a screenshot that shows Windows 7 is not quite there yet.
Parent - - By M ANSARI (*****) Date 2010-02-22 22:09
I thought Lukas said that he found no difference with HT on and off in Win 7.
Parent - By Master Om (Bronze) Date 2010-02-23 02:35
Where ?
Up Topic The Rybka Lounge / Computer Chess / Hyperthreading Results (Clemens Keck)

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