From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751341AbWHRKOT (ORCPT ); Fri, 18 Aug 2006 06:14:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751344AbWHRKOR (ORCPT ); Fri, 18 Aug 2006 06:14:17 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:58123 "EHLO spitz.ucw.cz") by vger.kernel.org with ESMTP id S1751342AbWHRKOM (ORCPT ); Fri, 18 Aug 2006 06:14:12 -0400 Date: Fri, 18 Aug 2006 08:39:12 +0000 From: Pavel Machek To: David Howells Cc: Andi Kleen , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org# Subject: Re: [RHEL5 PATCH 1/4] Provide fallback full 64-bit divide/modulus ops for gcc Message-ID: <20060818083911.GB7516@ucw.cz> References: <20060814211504.27190.10491.stgit@warthog.cambridge.redhat.com> <20060814211507.27190.61876.stgit@warthog.cambridge.redhat.com> <7510.1155630597@warthog.cambridge.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7510.1155630597@warthog.cambridge.redhat.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue 15-08-06 09:29:57, David Howells wrote: > Andi Kleen wrote: > > > At least Linus' traditional argument against this is that it's better > > to open code these (do_div) so that it's clear to the coder that they > > are really costly. > > do_div() is not a full replacement for __udivdi3(), __umoddi3() or > __udivmoddi4(), though I suspect we don't need divisor >= 2^32 anywhere atm. > > There are places where the compiler emits these that aren't entirely obvious, > one of which IIRC is in ext2 inode allocation. Well -- but that is good reason to keep that open-coded, right? -- Thanks for all the (sleeping) penguins.