From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id BE60E6B02A9 for ; Tue, 13 Jul 2010 12:44:35 -0400 (EDT) Received: by pwi8 with SMTP id 8so2732965pwi.14 for ; Tue, 13 Jul 2010 09:44:34 -0700 (PDT) Date: Wed, 14 Jul 2010 01:44:23 +0900 From: Minchan Kim Subject: Re: [RFC] Tight check of pfn_valid on sparsemem Message-ID: <20100713164423.GC2815@barrios-desktop> References: <20100712155348.GA2815@barrios-desktop> <20100713093006.GB14504@cmpxchg.org> <20100713154335.GB2815@barrios-desktop> <1279038933.10995.9.camel@nimitz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1279038933.10995.9.camel@nimitz> Sender: owner-linux-mm@kvack.org To: Dave Hansen Cc: Johannes Weiner , linux@arm.linux.org.uk, Yinghai Lu , "H. Peter Anvin" , Andrew Morton , Shaohua Li , Yakui Zhao , linux-kernel@vger.kernel.org, linux-mm@kvack.org, arm-kernel@lists.infradead.org, kgene.kim@samsung.com, Mel Gorman , KAMEZAWA Hiroyuki List-ID: Hi, Dave. On Tue, Jul 13, 2010 at 09:35:33AM -0700, Dave Hansen wrote: > On Wed, 2010-07-14 at 00:43 +0900, Minchan Kim wrote: > > 3 is not a big deal than 2 about memory usage. > > If the system use memory space fully(MAX_PHYSMEM_BITS 31), it just consumes > > 1024(128 * 8) byte. So now I think best solution is 2. > > > > Russell. What do you think about it? > > I'm not Russell, but I'll tell you what I think. :) > No problem. :) > Make the sections 16MB. You suggestion to add the start/end pfns I hope so. > _doubles_ the size of the structure, and its size overhead. We have > systems with a pretty tremendous amount of memory with 16MB sections. Yes. it does in several GB server system. > > If you _really_ can't make the section size smaller, and the vast > majority of the sections are fully populated, you could hack something > in. We could, for instance, have a global list that's mostly readonly > which tells you which sections need to be have their sizes closely > inspected. That would work OK if, for instance, you only needed to > check a couple of memory sections in the system. It'll start to suck if > you made the lists very long. Thanks for advise. As I say, I hope Russell accept 16M section. > > -- Dave > -- 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/ . Don't email: email@kvack.org