Re: [PATCH 1/5] locking: Introduce range reader/writer lock

[Kirill A. Shutemov]

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