Date: Fri, 23 Jun 2000 11:37:03 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: freebsd-smp@freebsd.org Subject: Stepping on Toes Message-ID: <200006231837.LAA11456@apollo.backplane.com>
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Hmm. Well, apparently I've stepped on a few toes by not using the
BSDI mutex code verbatim.
My position is this:
* I don't think we can use the BSDI mutex code verbatim
because we intend to keep legacy SPL support and it would take
as much work addressing that in the BSDI mutex code as it would
doing a new core-mutex piece from scratch.
* I think we CAN use the *WITNESS* code pretty much verbatim. The
reason it isn't in patch set #1 is because the witness code is
not going to be useful until we start unwinding the SPL code in
the system, and that is not going to happen until *after* heavy
weight interrupt threads are implemented. Until that time
(maybe a month or two from now?) it's just extra baggage.
It's the next logical step to take after the heavy weight
interrupt code is made to work, not before.
The witness code isn't going to help us for just the Sched and
Giant mutexes... simple KASSERT's deal with those situations.
In regards to the general project. If people want to try to port
the BSDI mutex code directly then be my guest. I've got a patch set
that works now ... I can successfully make buildworld on an SP machine
with it. You can try porting the BSDI mutex code with or without the
patchset I've already got, but if after a month or two if you still don't
have something that works I would recommend going back to the piecemeal
approach I have taken, starting with my patchset.
I won't be angry or anything if people decide to take this course,
even though I think it's the wrong course to take. But you guys have
to decide what to do ASAP.
-Matt
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