From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 7B4296B0089 for ; Thu, 18 Nov 2010 11:34:45 -0500 (EST) Date: Fri, 19 Nov 2010 00:34:39 +0800 From: Wu Fengguang Subject: Re: [PATCH] writeback: prevent bandwidth calculation overflow Message-ID: <20101118163439.GA21318@localhost> References: <20101118065725.GB8458@localhost> <4CE537BE.6090103@redhat.com> <20101118154408.GA18582@localhost> <1290096121.2109.1525.camel@laptop> <20101118160652.GA19459@localhost> <1290097740.2109.1527.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1290097740.2109.1527.camel@laptop> Sender: owner-linux-mm@kvack.org To: Peter Zijlstra Cc: Rik van Riel , Andrew Morton , Jan Kara , "Li, Shaohua" , Christoph Hellwig , Dave Chinner , Theodore Ts'o , Chris Mason , Mel Gorman , KOSAKI Motohiro , linux-mm , "linux-fsdevel@vger.kernel.org" , LKML List-ID: On Fri, Nov 19, 2010 at 12:29:00AM +0800, Peter Zijlstra wrote: > On Fri, 2010-11-19 at 00:06 +0800, Wu Fengguang wrote: > > On Fri, Nov 19, 2010 at 12:02:01AM +0800, Peter Zijlstra wrote: > > > On Thu, 2010-11-18 at 23:44 +0800, Wu Fengguang wrote: > > > > + pause = HZ * pages_dirtied / (bw + 1); > > > > > > Shouldn't that be using something like div64_u64 ? > > > > OK, but a dumb question: gcc cannot handle this implicitly? > > it could, but we chose not to implement the symbol it emits for these > things so as to cause pain.. that was still assuming the world of 32bit > computing was relevant and 64bit divides were expensive ;-) Good to know that, thanks! So let's avoid it totally :) -- 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