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 maybe it is what you're thinking of? I'm not as concerned about the contended performance of spinlocks for Linux as MS seems to be for windows (they seem to be very proud of this lock). Because if it is a big problem then IMO it is a bug. This was just something I had in mind when the hardware lock starvation issue came up, so I thought I should quickly code it up and RFC... actually it makes contended performance worse, but I'm not too worried about that because I'm happy I was able to implement it without increasing data size or number of locked operations. - 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/
