From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH 1/2] Revert "Revert "math64: New div64_u64_rem helper"" Date: Wed, 21 Aug 2013 09:21:23 +0200 Message-ID: <20130821072122.GA27360@gmail.com> References: <1376078164-23147-1-git-send-email-snitzer@redhat.com> <20130820070045.GA1665@redhat.com> <20130820080910.GA11072@gmail.com> <20130820192508.GA4799@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20130820192508.GA4799@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Mike Snitzer Cc: Stanislaw Gruszka , dm-devel@redhat.com, linux-kernel@vger.kernel.org, Mikulas Patocka , Frederic Weisbecker , "Alasdair G. Kergon" List-Id: dm-devel.ids * Mike Snitzer wrote: > On Tue, Aug 20 2013 at 4:09am -0400, > Ingo Molnar wrote: > > > > > * Stanislaw Gruszka wrote: > > > > > On Fri, Aug 09, 2013 at 03:56:03PM -0400, Mike Snitzer wrote: > > > > This reverts commit f3002134158092178be81339ec5a22ff80e6c308. > > > > > > > > div64_u64_rem was removed because there were no other users. > > > > > > > > But Device Mapper's I/O statistics support has a need for > > > > div64_u64_rem; reintroduce this helper. > > > > > > This slows down div64_u64 operation, especially on 32-bit > > > systems. > > > > > > Since dm statistic code is possibly not performance > > > critical perhaps you could use something like below > > > instead to calculate remainder: > > > > > > res = div64_u64(a, b); > > > rem = a - b*res; > > > > Or introduce a separately named helper without touching the > > existing methods. > > Thanks for the feedback. > > I've pushed "math64: New separate div64_u64_rem helper" to the DM tree's > 'for-next' branch: > https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=for-next&id=20e8125736d0e96b64c9b6127241d2a13529180a > > Are you OK with me carrying this patch in the DM tree for 3.12 > inclusion? Would be nice to include the actual latest patch here on lkml. Thanks, Ingo