title: Intel MSR frequency scaling per - thread
body: <p>I'm extending the Linux kernel in order to control the frequency of some threads: when they are scheduled onto a core (any core!), the core's frequency is changed by writing the proper p-state to the register <code>IA32_PERF_CTL</code>, as suggested in Intel's manual.
  But when different threads with different "custom" frequencies are scheduled, it appears that the throughput of all the thread increases, as if all the cores run at the maximum set frequency.</p>
  
  <p>I did many trials and measurements in different conditions of load and configuration, but the result is the same.
  After some trials with CPUFreq (with no running app, I set different frequencies on each core, and finally the measured frequencies, with cpufreq-info -w, were equal), I wonder if the CPU cores can <strong>really</strong> run at different, <strong>independent frequencies</strong>, or if there are hardware policies or constraints.</p>
  
  <p>Finally, is there a CPU model which makes this fine-grained frequency scaling feasible?</p>
  
  <p>The CPU I am using is Intel Core i5 750</p>