Linux 4.15 Gets Fixed To Report Current CPU Frequency Via /proc/cpuinfo

A change recently in the Linux kernel led the CPU MHz reported value via /proc/cpuinfo to either be the nominal CPU frequency or the most recently requested frequency. This behavior changed compared to pre-4.13 kernels while now it's been fixed up to report the current CPU frequency.

ACPI/PM maintainer Rafael Wysocki whipped up a new patch to ensure the current CPU frequency is always shown in /proc/cpuinfo and matches then what is shown by scaling_cur_freq on sysfs. He also had to workaround some situations where many-core systems would lead to slow access times for /proc/cpuinfo.

Today he sent this fix in this pull request for Linux 4.15 while it's also expected to be back-ported to Linux 4.14 to maintain the CPU frequency reporting behavior for /proc/cpuinfo.

This pull request comes a few days after the other ACPI and power management updates for Linux 4.15's ongoing merge window.