C2D L9400 @1.87
All cores
Run 1 = 283
Run 2 = 281
Affinity = Core 0 only
Run 1 = 287
Run 2 = 289
i5 M560 @2.67
All cores
Run 1 = 472
Run 2 = 470
Run 3 = 470
Run 4 = 468
Affinity = Core 0 only
Run 1 = 482
Run 2 = 483
Affinity = Core 1 only
Run 1 = 477
Run 2 = 477
Affinity = Core 3 only
Run 1 = 476
Affinity = Core 2 only
Run 1 = 482
Affinity = Cores 0 and 2
Run 1 = 470
Affinity = Cores 0 and 1
Run 1 = 481
Affinity = Cores 1 and 3
Run 1 = 477
Run 2 = 476
Affinity = Cores 2 and 3
Run 1 = 483
Affinity = Cores 1 and 2
Run 1 = 483
Affinity = Cores 0, 1, and 3
Run 1 = 480
Run 2 = 481
Affinity = Cores 0, 1, and 2
Run 1 = 471
All at stock config, plugged in. C2D is running W7 x64 Pro, and i5 M is running W7 Ent x32.
For both systems, there seems to be a ~2.2% advantage when running in single logical core config compared to all cores or >1 logical core. This is assuming that my recollection of cores 0 and 2 being logical and 1 and 3 HT for enabled systems is accurate.
The results with the mobile i5, however, suggest that one logical core + 1 HT core is equivalent to single-core-- furthermore, it seems that mixing and matching does not matter, as long as the criteria of one logical + 1 HT core is maintained.
Oddly, putting two HT cores (1 and 3) together results in a middle-of-the road effect. I thought maybe the first score of 477 could be variance, but the second run I did after writing this up indicates it may be real. Even stranger is 1 logical + 2 HT, which may be another tier of difference, or could just be noise-- I don't have enough n to lend statistical significance to such a tiny delta within the four different conditions. Maybe someone with higher clocks with an HT-capable CPU can provide definitive findings. I'm also too lazy to actually repeat this test while tracking CPU clock.
My guess is that turbo kicks in as follows:
1 logical OR 1 logical + 1 HT >= 1 logical + 2 HT >= 2 HT > 2 logical OR 2 logical + 1 OR 2 HT
It's probably safe to say that 1 logical or 1 logical/1HT > 2 HT OR 2 logical. What I don't know is whether 1 logical or 1 logical/1 HT > 1 logical/2HT. Likewise, I can't say for sure that the latter is > 2HT. Need many, many more data points (or just more data points if someone can provide higher clocks to get *presumably* larger deltas between conditions) to run ANOVA w/post-hoc testing for this many comparisons.
Edit: Realized I forgot about single HT core only. Ran another round with Core 1 only, and also threw in some other tests. Repeated two more rounds with all cores as a control.
Clearly, I need more analytical work at work.