On Wed, 28 Mar 2007, Davide Libenzi wrote: > On Wed, 28 Mar 2007, Nick Piggin wrote: > > > On Sat, Mar 24, 2007 at 06:29:59PM +0100, Ingo Molnar wrote: > > > > > > * Nikita Danilov <[EMAIL PROTECTED]> wrote: > > > > > > > Indeed, this technique is very well known. E.g., > > > > http://citeseer.ist.psu.edu/anderson01sharedmemory.html has a whole > > > > section (3. Local-spin Algorithms) on them, citing papers from the > > > > 1990 onward. > > > > > > that is a cool reference! So i'd suggest to do (redo?) the patch based > > > on those concepts and that terminology and not use 'queued spinlocks' > > > that are commonly associated with MS's stuff. And as a result the > > > contended case would be optimized some more via local-spin algorithms. > > > (which is not a key thing for us, but which would be nice to have > > > nevertheless) > > > > Firstly, the terminology in that paper _is_ "queue lock", which isn't > > really surprising. I don't really know or care about what MS calls their > > locks, but I'd suggest that their queued spinlock is probably named in > > reference to its queueing property rather than its local spin property. > > The method you propose is otherwise called "Ticket Lock": > > http://en.wikipedia.org/wiki/Ticket_lock > http://www.cs.rochester.edu/research/synchronization/pseudocode/ss.html#ticket
That this work prio-art dates to 1991: http://www.cs.rochester.edu/u/scott/papers/1991_TOCS_synch.pdf So I would not worry to much about patents here. At least W2K MS ones ;) What I would worry though, is to add another class of locks. There's no reason why Ticket Locks would perform worse than our spinlock, in both contended and not-contended case, AFAICS. And they have a nice FIFO behaviour. - Davide - 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/
