Breno Leitao wrote:

Nathan Lynch wrote:

quoted

There is an "interesting" quality of POWER6 cores, which each have 2
hardware threads: assuming one thread on the core is idle, the primary
thread is a little "faster" than the secondary thread.  To illustrate:
  

I found this feature interesting and decided to do some tests.
After some tests I found that the example you post really runs fast in  
the first CPU, but a more "elaborated" application runs slower on the  
first CPU.
Here is a small example:

# taskset 0x1 time -f "%e,  %U, %S" ./a.out ; taskset 0x2 time -f "%e,  
%U, %S" ./a.out
10.77,  10.72, 0.01
10.53, 10.48, 0.01

# taskset 0x2 time -f "%e,  %U, %S" ./a.out ; taskset 0x1 time -f "%e,  
%U, %S" ./a.out
10.55,  10.50, 0.01
10.77, 10.72, 0.01

I've been able to duplicate your results, thanks for the testcase.
Guess I'll need to understand what's going on before continuing with
this...