Hi all,

I have made a little benchmark of four operating systems, using a UCI engine.
I made four tests for each of the different OS. In the first test I run Stockfish using one thread, in the second I run it with two threads, etc.
The benchmark is based on an infinite search of the engine during ten minutes, from the start position board.
Here is a description of the conditions of the benchmark.

Desktop computer used :
  AMD Phenom(TM) 9750 Quad-Core Processor 2.40 GHz
  2,00 Go DDR2
Engine used :
  Stockfish 1.9.1 JA
  512 Mo Hash
Opering systems tested :
  Windows 7 Ultimate
  Fedora 14 (Laughlin), GNOME 2.32.0
  Ubuntu 10.10 (Maverick), GNOME 2.32.0
  Suse Linux 11.3, GNOME 2.30.0

The first test, Stockfish 1.9.1 JA running with one thread :


On one core, Stockfish performed better on all the Linux distributions than Windows 7.
In fact, it showed an average of 677 Kn/s, with a maximum of 731 Kn/s at 21^stsecond.
For Fedora 14 : average 755 Kn/s, maximum 815 Kn/s at 35^ths.
For Ubuntu 10.10 : average 755 Kn/s, maximum 816 Kn/s at 34^ths.
For Suse 11.3 : average 753 Kn/s, maximum 791 Kn/s at 35^ths.

The second test, Stockfish 1.9.1 JA running with two threads :


On two cores, same result. Suse Linux has clearly distinguished itself from the other OS.
Windows 7 : average of 1355 Kn/s, with a maximum of 1442 Kn/s at 25^ths.
Fedora 14 : average 1402 Kn/s, maximum 1556 Kn/s at 25^ths.
Ubuntu 10.10 : average 1399 Kn/s, maximum 1520 Kn/s at 17^ths.
Suse 11.3 : average 1444 Kn/s, maximum 1595 Kn/s at 19^ths.

The third test, Stockfish 1.9.1 JA running with three threads :


On three cores, the results starts to be different. Windows shows now the best average, but strangely not the best maximum.
Windows 7 : average of 2113 Kn/s, with a maximum of 2177 Kn/s at 28^ths.
Fedora 14 : average 2105 Kn/s, maximum 2263 Kn/s at 13^ths.
Ubuntu 10.10 : average 2090 Kn/s, maximum 2273 Kn/s at 10^ths.
Suse 11.3 : average 2088 Kn/s, maximum 2242 Kn/s at 13^ths.

The last test, Stockfish 1.9.1 JA running with four threads :


On four cores, Ubuntu and Fedora stays behind Windows, which scored equal with Suse. Fedora showed the best maximum.
Windows 7 : average of 2740 Kn/s, with a maximum of 2798 Kn/s at 31^sts.
Fedora 14 : average 2726 Kn/s, maximum 2930 Kn/s at 13^ths.
Ubuntu 10.10 : average 2720 Kn/s, maximum 2860 Kn/s at 19^ths.
Suse 11.3 : average 2741 Kn/s, maximum 2868 Kn/s at 8^ths.

Conclusion : Windows 7 seems to better manage the multi-core than the Linux distribution, although it'll be difficult to explain why it always had the worst maximum Kn/s.

NB : I noticed on "average" the Kn/s showed by the engine at the end of the 10 minutes of analysis.

Best regards,
Orlando