That's why when you get a real time you adjust the times on your logged events. There's the time you got the time fix, everything else is N microseconds before that back to when you started recording. So you record back to <time fix time> minus <recording duration>.
On Sun, Feb 21, 2021 at 12:19:31PM -0500, Alan Corey wrote:
> I think it's unreasonable to expect that kind of time accuracy from the
> first microsecond of bootup. Relative accuracy maybe, by counting cycles
> of a crystal oscillator and storing events in some buffer. Then once you
> have a good time reference write them all out to permanent storage by doing
> the arithmetic to assign real times to those events.
The kernel itself does exactly this.
But what does it tell the kernel about the "right" time in the rest of
the world (i.e. - any other host)? Exactly nothing.
End result - you can measure whatever happens during the boot just fine,
but you start 1st Jan 1970 0:00 each boot.
You see, the problem is not the timekeeping, it's the setting
more-or-less the same time on different systems.
Reco