Different clock frequency on hyper-threaded cores?

Question

I'm not sure if this is the right place to ask, It's not really an issue but has be bothering me for some time now and google didn't find an answer for me....
I'm currently using an i7-5500U with 2 physical cores (4 HT cores).
Yet, when I check the clock frequency on the system it shows a different value for each of the 4 HT cores:
cat /proc/cpuinfo | grep MHz
cpu MHz : 3001.031
cpu MHz : 2975.906
cpu MHz : 2994.468
cpu MHz : 2901.562
How can this be possible when there are only 2 physical cores?
Shouldn't the HT cores share the same frequency on the same physical core?
If I'm getting this right, hyper-threading simply means interleaving 2 instruction streams into a single (physical) core to reduce pipeline hazards right?
This just boggles my mind....
Last edited by akiroz (2015-06-06 19:05:33)

Answer 1

The numbers are different each time, here are 3 more samples:
cat /proc/cpuinfo | grep MHz
cpu MHz : 2937.187
cpu MHz : 2954.250
cpu MHz : 2977.500
cpu MHz : 2990.250
cat /proc/cpuinfo | grep MHz
cpu MHz : 2954.812
cpu MHz : 2981.812
cpu MHz : 2996.343
cpu MHz : 2987.062
cat /proc/cpuinfo | grep MHz
cpu MHz : 2969.250
cpu MHz : 2936.718
cpu MHz : 2985.093
cpu MHz : 2980.031