Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753779AbdC2Pkv (ORCPT ); Wed, 29 Mar 2017 11:40:51 -0400 Received: from mail-wr0-f178.google.com ([209.85.128.178]:34175 "EHLO mail-wr0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753782AbdC2Pks (ORCPT ); Wed, 29 Mar 2017 11:40:48 -0400 Date: Wed, 29 Mar 2017 18:40:39 +0300 From: "Kirill A. Shutemov" To: Davidlohr Bueso Cc: Laurent Dufour , mingo@kernel.org, peterz@infradead.org, akpm@linux-foundation.org, jack@suse.cz, kirill.shutemov@linux.intel.com, mhocko@suse.com, mgorman@techsingularity.net, linux-kernel@vger.kernel.org, Davidlohr Bueso Subject: Re: [PATCH 1/5] locking: Introduce range reader/writer lock Message-ID: <20170329154039.sbmk4hfrgstj4w3s@node.shutemov.name> References: <1488863010-13028-1-git-send-email-dave@stgolabs.net> <1488863010-13028-2-git-send-email-dave@stgolabs.net> <2f7628f4-58e1-22c4-ccbe-3106c15cb405@linux.vnet.ibm.com> <20170328163918.GA27446@linux-80c1.suse> <20170328165803.podjvgo5zim44gip@node.shutemov.name> <5df9746e-a671-ed3f-89a1-fb6fe6ec4f4e@linux.vnet.ibm.com> <20170329153133.GG27446@linux-80c1.suse> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170329153133.GG27446@linux-80c1.suse> User-Agent: NeoMutt/20170306 (1.8.0) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1079 Lines: 25 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