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Date:      Tue, 5 Feb 2002 09:06:51 -0800 (PST)
From:      John Polstra <jdp@polstra.com>
To:        hackers@freebsd.org
Cc:        jhb@freebsd.org
Subject:   Re: A question about timecounters
Message-ID:  <200202051706.g15H6pp03714@vashon.polstra.com>
In-Reply-To: <XFMail.020204234209.jhb@FreeBSD.org>
References:  <XFMail.020204234209.jhb@FreeBSD.org>

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In article <XFMail.020204234209.jhb@FreeBSD.org>,
John Baldwin  <jhb@FreeBSD.ORG> wrote:
> 
> > like, "If X is never locked out for longer than Y, this problem
> > cannot happen."  I'm looking for definitions of X and Y.  X might be
> > hardclock() or softclock() or non-interrupt kernel processing.  Y
> > would be some measure of time, probably a function of HZ and/or the
> > timecounter frequency.
> 
> X is hardclock I think, since hardclock() calls tc_windup().

That makes sense, but on the other hand hardclock seems unlikely to be
delayed by much.  The only thing that can block hardclock is another
hardclock, an splclock, or an splhigh.  And, maybe, splstatclock.  I'm
talking about -stable here, which is where I'm doing my experiments.

John
-- 
  John Polstra
  John D. Polstra & Co., Inc.                        Seattle, Washington USA
  "Disappointment is a good sign of basic intelligence."  -- Chögyam Trungpa


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