On Mon, Jul 27, 2015 at 01:20:02PM -0700, Davidlohr Bueso wrote: > On Mon, 2015-07-27 at 13:03 -0700, Andrew Morton wrote: > > On Sat, 25 Jul 2015 15:35:24 -0700 Josh Triplett <josh@xxxxxxxxxxxxxxxx> wrote: > > > > > > Some mm functionality might very possibly rely on srcu in the future if > > > > we expect any chances of scaling, ie: faults. So I'd rather not take a > > > > short term solution here, as we'll probably be discussing this again > > > > otherwise. > > > > > > What other mm functionality plans to use SRCU? > > Right now I have (unpublished) patches that use srcu as a way to avoid > mmap_sem when faulting across the entire path. Previous alternatives > also use it, as ie, can involve IO and lots of other sleeping > operations. That sounds interesting! mmap_sem is definitely a performance bottleneck. How do you handle writes versus reads? > Yes, you can argue that they're not published all you want, > but I'm talking beyond my specific use case. Linux VM is known to scale, > why should we hide a core scalability tool from it? In the case of mmap_sem, does it help at all if tiny kernels were 1) non-preemptible and 2) non-SMP? Tiny kernels don't necessarily care about scaling. > > > Among other things, no-mmu builds might still be able to omit it. > > > > Yup. > > Makes sense. Thanks. - Josh Triplett -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
