|Matthew Dillon||Jun 23, 2000 11:36 am|
|David Greenman||Jun 24, 2000 9:10 pm|
|Matthew Dillon||Jun 25, 2000 10:24 am|
|Jake Burkholder||Jun 25, 2000 11:19 am|
|Chuck Paterson||Jun 26, 2000 9:50 am|
|Matthew Dillon||Jun 27, 2000 10:41 am|
|Chuck Paterson||Jun 27, 2000 11:19 am|
|Kevin Van Maren||Jun 29, 2000 1:52 pm|
|Greg Lehey||Jul 2, 2000 6:51 pm|
|Jason Evans||Jul 3, 2000 8:41 am|
|Jake Burkholder||Jul 3, 2000 1:14 pm|
|Jake Burkholder||Jul 5, 2000 2:23 am|
|Matthew Dillon||Jul 5, 2000 9:43 am|
|Chuck Paterson||Jul 5, 2000 9:52 am|
|Chuck Paterson||Jul 5, 2000 9:57 am|
|Luoqi Chen||Jul 5, 2000 10:29 am|
|Matthew Dillon||Jul 5, 2000 11:28 am|
|Greg Lehey||Jul 5, 2000 4:20 pm|
|Doug Rabson||Jul 6, 2000 1:26 am|
|Matthew Dillon||Jul 6, 2000 10:43 am|
|Greg Lehey||Jul 22, 2000 2:26 am|
|Matthew Dillon||Jul 22, 2000 9:20 am|
|Chuck Paterson||Jul 22, 2000 9:57 am|
|Bruce Evans||Jul 22, 2000 10:36 am|
|Greg Lehey||Jul 23, 2000 8:14 pm|
|Bruce Evans||Jul 24, 2000 1:08 am|
|Chuck Paterson||Jul 24, 2000 6:43 am|
|Matthew Dillon||Jul 24, 2000 9:16 am|
|Subject:||Re: Stepping on Toes|
|From:||David Greenman (dg...@root.com)|
|Date:||Jun 24, 2000 9:10:56 pm|
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.
Of course we need to wait a few days for people to return from Usenix. I just got back myself a few hours ago and have over 3000 emails to deal with. My general view is that we should probably go directly to the threaded interrupt model and dump spls in the first cut. Given this, I think it would be prudent to use as much of the BSDI mutex code as possible, at least for the medium term, since it has been well tested and debugged. Not using it reaks of NIH to folks on the outside, even though the SMPng group (at least) knows that that wasn't at all your motivation in rolling your own.
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