[Gems-users] different number of cycles, Simics and GEMS

[Andrew Green <andgr09@xxxxxxxxx>]

Dear all,
I ran Freqmine (a benchmark from PARSEC) from the beginning of ROI to
the end of ROI with simics (ipc=1) and got the total cycles equal to
49,206,002,380. So about 50b instructions where executed in ROI. I
calculated that number in this way:

simics> magic-break-enable
simics> $start = (ptime -s)
.....
simics> c
...... got magic
simics> $finish = (ptime -s)
....
simics> $finish - $start

However with GEMS, I get a very different number:

instruction_executed: 227,385,079,675 [ 52866792093 56921608271
59666582857 57930096454 ]
simics_cycles_executed: 298,940,409,581 [ 74735102396 74735102395
74735102395 74735102395 ]
cycles_per_instruction: 0.328672 [ 0.353412 0.328237 0.313136 0.322523 ]

How does GEMS calculate "simics_cycles_executed"?