Add Pressure Stall Information into Kernel

[rikatz]

Current situation
Current Kernel version supports PSI, which might help system administrators to detect bottleneck in cpu, memory and io in a easy way.

This is just a CONFIG_PSI=y in the Kernel configuration, and can also be used by cgroups2

Impact
Make the bottleneck and latency detection easier.

Kernel will get a little bigger (new feature), and a new /proc/pressure directory will be created.

Ideal future situation
PSI Enabled by default

Implementation options
Change the kernel config to contain CONFIG_PSI=y

Additional information

PTAL https://facebookmicrosites.github.io/psi/docs/overview

Thank you!!

[dongsupark]

Yeah, I remember that Johannes Weiner gave a talk about PSI last year at All Systems Go.
I think it is a well-designed feature, used by a fair amount of userspace tools.
👍

[dongsupark]

Filed a PR flatcar-archive/coreos-overlay#638.

[rikatz]

Thank you!!