Nick Piggin writes: > On Fri, Mar 23, 2007 at 11:04:18AM +0100, Ingo Molnar wrote: > > > > * Nick Piggin <[EMAIL PROTECTED]> wrote: > > > > > Implement queued spinlocks for i386. [...] > > > > isnt this patented by MS? (which might not worry you SuSE/Novell guys, > > but it might be a worry for the rest of the world ;-) > > Hmm, it looks like they have implemented a system where the spinning > cpu sleeps on a per-CPU variable rather than the lock itself, and > the releasing cpu writes to that variable to wake it. They do this > so that spinners don't continually perform exclusive->shared > transitions on the lock cacheline. They call these things queued > spinlocks. They don't seem to be very patent worthy either, but
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. Nikita. - 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/
