Messages in this thread | | | From | Alexey Klimov <> | Date | Fri, 6 Dec 2019 14:47:13 +0000 | Subject | Re: Running an Ivy Bridge cpu at fixed frequency |
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On Wed, Dec 4, 2019 at 5:32 PM David Laight <David.Laight@aculab.com> wrote: > > Is there any way to persuade the intel_pstate driver to make an Ivy bridge (i7-3770) > cpu run at a fixed frequency? > It is really difficult to compare code execution times when the cpu clock speed > keeps changing. > I thought I'd managed by setting the 'scaling_max_freq' to 1.7GHz, but even that > doesn't seem to be working now. > It would also be nice to run a little faster than that - but without it 'randomly' > going to 'turbo' frequencies (which it is doing even after I've set no_turbo to 1). > > An alternative would be a variable frequency TSC - might give more consistent values.
Have you tried intel_pstate=passive parameter in cmdline? You'll be able to fix the frequency using governors or sysfs. Not sure that this is what you're looking for. I personally also don't know that 'passive' mode will work on Ivy Bridge.
Best regards, Alexey
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