In article <[EMAIL PROTECTED]>, David Greenman
<[EMAIL PROTECTED]> wrote:
> >I will add that this is the pattern that Kirk teaches in his kernel
> >internals class.
>
> If that's true,
Do you want me to fax you a copy of page 15 of his class notes from
the course he gave at last year's FreeBSDCon, or will you just take my
word for it?
> then he should practice what he preaches. Some of the code that I'm
> refering to (e.g. lockf) was apparantly written by him.
Whether Kirk practices what he preaches is irrelevant to this
discussion. Instead of focusing on a 1-sentence "I will add ..." from
my posting, why not respond to the main thrust of it -- the paragraph
I quoted from the Birrell paper?
> I'll say again, however, that some of the cases that rely on the
> historical symantics would become very expensive if they had to go
> through a series of complex checks (perhaps list traversals, etc),
> in order to verify that the wakeup wasn't bogus. I personally don't
> think this is an improvement.
Some of them might be expensive, but most of them would not.
Obviously the waker-upper knows that the condition is true. Otherwise
the existing code which doesn't check wouldn't work. In the expensive
cases the waker-upper could simply set a flag for the sleeper to
check.
Note, I am not expressing an opinion about whether the sleeps should
be terminated prematurely during shutdown. But I am expressing a
strong opinion about whether sleepers should do a reality check before
proceeding.
John
--
John Polstra [EMAIL PROTECTED]
John D. Polstra & Co., Inc. Seattle, Washington USA
"Disappointment is a good sign of basic intelligence." -- Chögyam Trungpa
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