From owner-freebsd-chat  Fri Oct 19 14:21:30 2001
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Date: Thu, 18 Oct 2001 23:26:03 -0600
To: John Baldwin <jhb@FreeBSD.ORG>
From: Brett Glass <brett@lariat.org>
Subject: Re: Breaking news: FreeBSD is "considering implementing a
  preemp
Cc: chat@FreeBSD.ORG, Dag-Erling Smorgrav <des@ofug.org>
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At 11:13 PM 10/16/2001, John Baldwin wrote:

>The only remaining trick is
>to not preempt during critical sections which are already marked by our
>critical_enter/exit API.

That's the hardest part: recognizing, in existing code, what's a
critical section. It may be non-obvious what will leave the kernel data
structures inconsistent in some subtle way -- especially if it involves
data values that should not be present at the same time rather than
dangling pointers.

--Brett


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