2 cores/threads don't come up to full speed

Framework Laptop 13
#1

Has anyone else seen behavior like this (powertop output shown):

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“CPUs” number 0 and 3 don’t run nearly as fast as the others. Powertop here is showing an average, but If I take snapshots of the frequency, the rest will run mostly around 2400 MHz (the nominal speed for the i5-1135G7), but 0 and 3 will more frequently bounce down to lower frequencies.

What’s particularly odd about it to me is that I’m pretty sure a “CPU” as exposed to Linux is really a hyperthreading thread, and the frequency only varies core by core, so it’s odd that powertop seems to show these “slow” CPUs being on different cores. It’s consistently 0 and 3 and maintains under load, so I don’t think it’s just cores not really doing anything.

I’m just wondering if anyone else has noticed this kind of behavior, really.

3 Likes
#2

I would try observing the the CPU clocking behavior with the “i7z” utility:

It understands the difference between cores and hyperthreads, and also tells you info about the C-states that each core operates in.

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#3

Thanks for the advice, though this didn’t seem to work for me out of the box… I’m thinking because of MSR restrictions when running on Secure Boot? Not sure.

Though it does run enough to confirm what powertop says and the usual situation, that the correct pairs of logical CPUs are 0&4, 1&5, 2&6, 3&7. So there’s still something odd about the way 0 and 3 are working and/or being reported.

1 Like