On Mon, 2015-07-27 at 13:31 -0700, josh@xxxxxxxxxxxxxxxx wrote: > That sounds interesting! mmap_sem is definitely a performance > bottleneck. How do you handle writes versus reads? The idea is to make vmas srcu aware, such that their lookups in the vmacache are lockless and can survive the entire fault path, among others we have ->vm_file. We simply handle cases when the vma/page-tables have changed between when the lookup was done and when we grab the pte lock with mmap_sem. These invalidations are a pain, albeit non fatal in some cases. > > > 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. Yes, I believe it would! I actually assumed tiny kernels were already UP. I don't think it makes much sense to have it at that level. Same with preemption. Thanks, Davidlohr -- 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
