From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id A8F356B0096 for ; Sat, 6 Nov 2010 13:31:14 -0400 (EDT) Received: by iwn9 with SMTP id 9so4104667iwn.14 for ; Sat, 06 Nov 2010 10:31:13 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1288973333-7891-1-git-send-email-minchan.kim@gmail.com> <20101106010357.GD23393@cmpxchg.org> Date: Sun, 7 Nov 2010 02:31:13 +0900 Message-ID: Subject: Re: [PATCH] memcg: use do_div to divide s64 in 32 bit machine. From: Minchan Kim Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Greg Thelen Cc: hannes@cmpxchg.org, Andrew Morton , Dave Young , Andrea Righi , KAMEZAWA Hiroyuki , Daisuke Nishimura , Balbir Singh , Wu Fengguang , Linux Kernel Mailing List , linux-mm List-ID: On Sun, Nov 7, 2010 at 2:19 AM, Greg Thelen wrote: > On Fri, Nov 5, 2010 at 6:03 PM, =A0 wrote: >> On Sat, Nov 06, 2010 at 01:08:53AM +0900, Minchan Kim wrote: >>> Use do_div to divide s64 value. Otherwise, build would be failed >>> like Dave Young reported. >> >> I thought about that too, but then I asked myself why you would want >> to represent a number of pages as signed 64bit type, even on 32 bit? > > I think the reason that 64 byte type is used for page count in > memcontrol.c is because the low level res_counter primitives operate > on 64 bit counters, even on 32 bit machines. > >> Isn't the much better fix to get the types right instead? >> > > I agree that consistent types between mem_cgroup_dirty_info() and > global_dirty_info() is important. =A0There seems to be a lot of usage of > s64 for page counts in memcontrol.c, which I think is due to the > res_counter types. =A0I think these s64 be switched to unsigned long > rather to be consistent with the rest of mm code. =A0It looks like this > will be a clean patch, except for the lowest level where > res_counter_read_u64() is used, where some casting may be needed. > > I'll post a patch for that change. > Agree. I don't mind it. Thanks, Hannes and Greg. --=20 Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org