Error in Unhalted.CPU.CLK cycles event

Error in Unhalted.CPU.CLK cycles event

Hi,

I am using an Intel core 2 duo for my experiments. I took the values for event Unhalted.CPU.CLK cycles
from performance counters for every 50 ms at 3 GHz and I think there is some error in these values.

11756688
10755981
11339255
10379462
11238271
17075903
11306373
10322670
11104972
10365042
10886639
12215434
11350157
10346371
11159237
10165709
10906594
9851367
10383997
9545022
9906189
8985392
10931922
8694046
9501240
8551339
9486363
8772000
9425110
8724505
9616005
10041717
9693242
8778631
9761600
8680658
9734474
9624267
9511117
8797080
9533306
8510488
9585389
8690431
9682885

I assume the values should be close to 50*10^-3 * 3*10^9=150000000, but the above values are much lower than that and I took these values when I was not executing any application.

Can anybody please explain whay this is happening.

Thank You.

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Hi gokussj9,

The unhalted core cycle event counter (Unhalted.CPU.CLK)does not advance if the ACPI C-state of the core is not C0 orHLT instruction is executed and in a few other cases. If you are not executing anyapplication thecores may be put inapower savingC-state (>0) and/or execute the idle loopin the OS scheduler (which can have the HLT instruction inside).

I hope this gives answer to your question.

Roman

Hi gokussj9,

the new Platform Monitoring portalmight be interesting for you to check out.

Roman

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