Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751699Ab3HTTZP (ORCPT ); Tue, 20 Aug 2013 15:25:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36047 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751130Ab3HTTZN (ORCPT ); Tue, 20 Aug 2013 15:25:13 -0400 Date: Tue, 20 Aug 2013 15:25:08 -0400 From: Mike Snitzer To: Ingo Molnar Cc: Stanislaw Gruszka , dm-devel@redhat.com, linux-kernel@vger.kernel.org, Mikulas Patocka , Frederic Weisbecker , "Alasdair G. Kergon" Subject: Re: [PATCH 1/2] Revert "Revert "math64: New div64_u64_rem helper"" Message-ID: <20130820192508.GA4799@redhat.com> References: <1376078164-23147-1-git-send-email-snitzer@redhat.com> <20130820070045.GA1665@redhat.com> <20130820080910.GA11072@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130820080910.GA11072@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1414 Lines: 42 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? Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/