On Wed, Mar 29, 2017 at 08:31:33AM -0700, Davidlohr Bueso wrote: > On Wed, 29 Mar 2017, Laurent Dufour wrote: > > > On 28/03/2017 18:58, Kirill A. Shutemov wrote: > > > On Tue, Mar 28, 2017 at 09:39:18AM -0700, Davidlohr Bueso wrote: > > > > I'll wait to see if there are any more concerns and send a v2 with your > > > > corrections. > > > > > > Have you tried drop-in replacement of mmap_sem with full range lock? > > > It would be interesting to see performance implication for this. > > > > > > > I've a patch that replace the mmap_sem with a full range lock, it seems > > to work fine for x86 and ppc64 for now. I'll send it soon. > > But I didn't yet check for performance. What is the best way to that ? > > I expect performance to take a measurable hit if we simply use full range > lock as a drop in replacement. My rwsem vs range lock measurements were > done with this in mind. We only win with range locks when improving the > level of parallelism.
It would be hard sell if we would see performance degradation simple single-threaded workload. -- Kirill A. Shutemov
