[MacOS] psutil.cpu_freq() broken on Apple M1

[Lomanic]

Summary

• OS: MacOS
• Architecture: Apple M1
• Psutil version: N/A
• Python version: N/A
• Type: core

Description

Sorry that I couldn't provide some of the info in the template as I don't own an Apple M1 device, but it is highly suspected that calling psutil.cpu_freq() on Apple M1 is failing as the hw.cpufrequency sysctl call (used here) was removed on this arch (can be checked with sysctl hw.cpufrequency on any Apple M1 device, while it is working on amd64).

See shirou/gopsutil#999 and shirou/gopsutil#1000

In shirou/gopsutil#999 a fix was suggested but I couldn't confirm it.

psutil user-base is probably bigger than gopsutil's so I hope this will help both projects find a solution or confirm @shoenig fix in his PR.

[giampaolo]

Mmm... is "hw.cpufrequency" the only one that fails? Later on we also use "hw.cpufrequency_min" and "hw.cpufrequency_max". Do they fail as well?

Sorry that I couldn't provide some of the info in the template

It's OK, no worries.

[tmm1]

None are present.

tmm1@Mac-mini ~ % sysctl hw.cpufrequency
tmm1@Mac-mini ~ % sysctl hw.cpufrequency_min
tmm1@Mac-mini ~ % sysctl hw.cpufrequency_max
tmm1@Mac-mini ~ %

[giampaolo]

For a possible solution see #975 pointing to https://stackoverflow.com/a/14355710/376587 (use sysctl + HW_CPU_FREQ or sysctl + KERN_CLOCKRATE). It looks like both approaches report the advertised frequency (it never changes), same as the current code.

[tmm1]

tmm1@Mac-mini /tmp % cat freq.c 

#include <stdio.h>
#include <sys/sysctl.h>

int main() {
        int mib[2];
        unsigned int freq;
        size_t len;

        mib[0] = CTL_HW;
        mib[1] = HW_CPU_FREQ;
        len = sizeof(freq);
        sysctl(mib, 2, &freq, &len, NULL, 0);

        printf("%u\n", freq);

      mib[0] = CTL_KERN;
      mib[1] = KERN_CLOCKRATE;
      struct clockinfo clockinfo;
      len = sizeof(clockinfo);
      sysctl(mib, 2, &clockinfo, &len, NULL, 0);
      printf("clockinfo.hz: %d\n", clockinfo.hz);
      printf("clockinfo.tick: %d\n", clockinfo.tick);

        return 0;
}
tmm1@Mac-mini /tmp % gcc -o freq freq.c 
tmm1@Mac-mini /tmp % ./freq
0
clockinfo.hz: 100
clockinfo.tick: 10000

tmm1@Mac-mini /tmp % sysctl kern.clockrate
kern.clockrate: { hz = 100, tick = 10000, tickadj = 0, profhz = 100, stathz = 100 }

[giampaolo]

According to doc we should return 0 if min and max frequency cannot be determined, so we can ignore those on M1. This was tracked in #1456 (we return error instead of 0) which should also be fixed.

[giampaolo]

Fixed by #1895.

[Lomanic]

psutil still uses hw.cpufrequency from what I see (but using the mib mechanism), this is still returning 0 on Apple M1 as per #1892 (comment), so I'm quite confused by the fix. Is the fix that now it returns 0 instead of returning an error?

[giampaolo]

Oh you're right. I misread #1892 (comment).