On Saturday, September 1, 2018, Steve Mynott <steve.mynott@gmail.com> wrote:
On Wed, 29 Aug 2018 at 15:53, Larry McVoy <
lm@mcvoy.com> wrote:
The BSDs have a less than optimal VM system. Having SunOS opened up
would at least let people see what they are missing. Maybe I have
rose colored glasses on but it was the only kernel that came into
focus for me and you could see the architecture from the code.
Everything else seems like a mess to me.
That may have been true in the late 80s and even early 90s but I'd have thought FreeBSD, NetBSD and OpenBSD would have useable VMs by now.
I've vague recollections that these all originally used the VM from Mach which did have problems at first.
Yes. CSRG used Mach VM because it was available, not because it was awesome. The folks at CSRG approached Sun to have them donate their VM to BSD, and there were serious talks about doing this until the lawyers got involved and explained that would require a serious write down on their quarterly report so that nixed the whole thing.
I recall a more knowledgeable friend complaining about FreeBSD VM in 1994 or so.
It used to be downright aweful.
I think the latter two use UVM and FreeBSD improved their Mach one (which has a SunOS kvmish API anyway). I've not seen complaints about modern BSD.
OpenBSD and NetBSD both moved to uvm.
Wasn't the whole FreeBSD VM rewritten by John Dyson and David Greenman in the mid-late 90's? And then further improved by Matthew Dillon.
Unfortunately they are not affiliated with the project anymore. All three had exceptional coding skills.
With the exception of David, it's not unfortunate at all. Although they were good for the project's code, they weren't good for the project. They didn't work well with others and caused much more grief than the code they contributed. There comes a time when there's just too much drama and the rest of the code gets much much better when you aren't always fighting drama :(. It was a tough decision to make when I was on the core team to show Dillon the door. One not made lightly, nor without a lot of effort to work through the issues. In the end, though, we had to part ways. Dillon has done well with DragonFly, however.
In the last 10 years or so there's been a number of people that have stepped up and replaced them, most notably Allan Cox and Mark Johnston who have mad coding skills and can play well with others. Though I'm sure I'm slighting several people by not mentioning them.
Warner