On Fri, Mar 28, 2008 at 05:15:20AM +0100, Nick Piggin wrote: > On Thu, Mar 27, 2008 at 09:09:10PM -0700, David Miller wrote: > > From: Nick Piggin <npiggin@xxxxxxx> > > Date: Fri, 28 Mar 2008 05:04:42 +0100 > > > > > BTW. if you are still interested, then the powerpc64 patch might be a > > > better starting point for you. I don't know how the sparc tlb flush > > > design looks like, but if it doesn't do a synchronous IPI to invalidate > > > other threads, then you can't use the x86 approach. > > > > I have soft bits available on sparc64, that's not my issue. > > > > My issue is that if you implemented this differently, every platform > > would get the optimization, without having to do anything special > > at all, and I think that's such a much nicer way. > > Oh, they wouldn't. It is completely tied to the low level details of > their TLB and pagetable teardown design. That's the unfortunate part > about it. > > The other thing is that the "how do I know if I can refcount the page > behind this (mm,vaddr,pte) tuple" can be quite arch specific as well. > And it is also non-trivial to do because that information can be dynamic > depending on what driver mapped in that given tuple. > > It is *possible*, but not trivial. And, btw, you'd still have to implement the actual fast_gup completely in arch code. So once you do that, you are free not to use pte_special for it anyway. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
