Re: Proposal to fix buggy PCC.

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

> Date: Mon, 15 Jan 2018 01:33:41 +0900
> From: "Naruaki.Etomi" <nullnilaki%gmail.com@localhost>
> 
> I propose to fix buggy PCC.

Cool, thanks for working on this!  I don't have time to review it
right now, but the main point that is broken in many of our per-CPU
timecounters is that the timecounter API is designed to provide a
_global_ clock, so it gets confused if you only present a per-CPU
clock.

Of course you can always turn a per-CPU clock into a global clock by
maintaining the most recent global timestamp the system has seen using
atomic operations or a lock.  One of these days we should add a
per-CPU timecounter API and a generic way to make a global timecounter
out of it -- but we don't have that yet.