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Re: timekeeping regression?



At Thu, 06 Jun 2024 21:43:46 -0700, "Greg A. Woods" <woods%planix.ca@localhost> wrote:
Subject: Re: timekeeping regression?
>
> The "hvm" domUs are running FreeBSD and have no problems.  They're using
> what they call XENTIMER as their timecounter clock source.  The FreeBSD
> code is very different, at least on first glance, and somewhat more
> convoluted in some ways.  I don't see an obvious "rdtsc" instruction
> being used, but there are hints that's what it is doing, but I may be
> wrong.

Never mind.   The rdtsc() call was staring at me when I looked at the
same FreeBSD code again this morning.

So, that kinda puts the onus for this regression back on NetBSD somehow,
though I don't understand how it could be so sensitive to which version
of Xen it's running under.

I keep thinking there might be some kind of overflow or similar, but
none of the obvious magic numbers seem to jump out as relevant to me,
though I'm a bit rusty at thinking in those terms.

--
					Greg A. Woods <gwoods%acm.org@localhost>

Kelowna, BC     +1 250 762-7675           RoboHack <woods%robohack.ca@localhost>
Planix, Inc. <woods%planix.com@localhost>     Avoncote Farms <woods%avoncote.ca@localhost>

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