On Tue, 2007-03-06 at 05:41 +0100, Willy Tarreau wrote: > On Tue, Mar 06, 2007 at 11:18:44AM +1100, Con Kolivas wrote: > > On Tuesday 06 March 2007 10:05, Bill Davidsen wrote: > > > jos poortvliet wrote: > > > > Well, imho his current staircase scheduler already does a better job > > > > compared to mainline, but it won't make it in (or at least, it's not > > > > likely). So we can hope this WILL make it into mainline, but I wouldn't > > > > count on it. > > > > > > Wrong problem, what is really needed is to get CPU scheduler choice into > > > mainline, just as i/o scheduler finally did. Con has noted that for some > > > loads this will present suboptimal performance, as will his -ck patches, > > > as will the default scheduler. Instead of trying to make ANY one size > > > fit all, we should have a means to select, at runtime, between any of > > > the schedulers, and preferably to define an interface by which a user > > > can insert a new scheduler in the kernel (compile in, I don't mean > > > plugable) with clear and well defined rules for how that can be done. > > > > Been there, done that. Wli wrote the infrastructure for plugsched; I took > > his > > code and got it booting and ported 3 or so different scheduler designs. It > > allowed you to build as few or as many different schedulers into the kernel > > and either boot the only one you built into your kernel, or choose a > > scheduler at boot time. That code got permavetoed by both Ingo and Linus. > > After that I gave up on that code and handed it over to Peter Williams who > > still maintains it. So please note that I pushed the plugsched barrow > > previously and still don't think it's a bad idea, but the maintainers think > > it's the wrong approach. > > In a way, I think they are right. Let me explain. Pluggable schedulers are > useful when you want to switch away from the default one. This is very useful > during development of a new scheduler, as well as when you're not satisfied > with the default scheduler. Having this feature will incitate many people to > develop their own scheduler for their very specific workload, and nothing > generic. It's a bit what happened after all : you, Peter, Nick, and Mike > have worked a lot trying to provide alternative solutions. > > But when you think about it, there are other OSes which have only one > scheduler > and which behave very well with tens of thousands of tasks and scale very well > with lots of CPUs (eg: solaris). So there is a real challenge here to try to > provide something at least as good and universal because we know that it can > exist. And this is what you finally did : work on a scheduler which ought to > be > good with any workload.
Solaris has a pluggable scheduler framework (each policy -- OTHER/FIFO/RR/etc. -- is it's own separate component). -- Nicholas Miell <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/