2005-09-26 21:03:49

by Roland McGrath

[permalink] [raw]
Subject: Re: [PATCH 2.6.13-rc6-rt9] PI aware dynamic priority adjustment

> On another issue along this line, I have been thinking of changing the
> x86 TSC arch cycle size to 1ns. (NOT the resolution, the units for the
> arch cycle.) The reason to do this is to correctly track changes in cpu
> frequency as it is today, we would need to track down and update all
> pending HR timers when ever the frequency changed. By using a common
> unit all we need to do is change the conversion constants (well I guess
> they would not be constants any more :). I REALLY don't want to do this
> as it does add conversion overhead, but I can not think of another clean
> way to track TSC frequency changes.

sched_clock does this conversion at sampling time, too.