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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20170329154039.sbmk4hfrgstj4w3s@node.shutemov.name>
Date:   Wed, 29 Mar 2017 18:40:39 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Davidlohr Bueso <dave@...olabs.net>
Cc:     Laurent Dufour <ldufour@...ux.vnet.ibm.com>, mingo@...nel.org,
        peterz@...radead.org, akpm@...ux-foundation.org, jack@...e.cz,
        kirill.shutemov@...ux.intel.com, mhocko@...e.com,
        mgorman@...hsingularity.net, linux-kernel@...r.kernel.org,
        Davidlohr Bueso <dbueso@...e.de>
Subject: Re: [PATCH 1/5] locking: Introduce range reader/writer lock

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