From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 2F8656B0092 for ; Mon, 8 Nov 2010 17:39:03 -0500 (EST) Date: Mon, 8 Nov 2010 23:38:38 +0100 From: Johannes Weiner Subject: Re: [patch 1/4] memcg: use native word to represent dirtyable pages Message-ID: <20101108223838.GM23393@cmpxchg.org> References: <1288973333-7891-1-git-send-email-minchan.kim@gmail.com> <20101106010357.GD23393@cmpxchg.org> <20101107215030.007259800@cmpxchg.org> <20101107220353.115646194@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Greg Thelen Cc: Minchan Kim , Andrew Morton , Dave Young , Andrea Righi , KAMEZAWA Hiroyuki , Daisuke Nishimura , Balbir Singh , Wu Fengguang , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Mon, Nov 08, 2010 at 02:25:15PM -0800, Greg Thelen wrote: > Minchan Kim writes: > > > On Mon, Nov 8, 2010 at 7:14 AM, Johannes Weiner wrote: > >> The memory cgroup dirty info calculation currently uses a signed > >> 64-bit type to represent the amount of dirtyable memory in pages. > >> > >> This can instead be changed to an unsigned word, which will allow the > >> formula to function correctly with up to 160G of LRU pages on a 32-bit > Is is really 160G of LRU pages? On 32-bit machine we use a 32 bit > unsigned page number. With a 4KiB page size, I think that maps 16TiB > (1<<(32+12)) bytes. Or is there some other limit? Yes, the dirty limit we calculate from it :) We have to be able to multiply this number by up to 100 (maximum dirty ratio value) without overflowing. -- 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