From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 5 Aug 2008 12:11:48 +0100 From: Mel Gorman Subject: Re: [RFC] [PATCH 0/5 V2] Huge page backed user-space stacks Message-ID: <20080805111147.GD20243@csn.ul.ie> References: <20080730014308.2a447e71.akpm@linux-foundation.org> <20080730172317.GA14138@csn.ul.ie> <20080730103407.b110afc2.akpm@linux-foundation.org> <20080730193010.GB14138@csn.ul.ie> <20080730130709.eb541475.akpm@linux-foundation.org> <20080731103137.GD1704@csn.ul.ie> <1217884211.20260.144.camel@nimitz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1217884211.20260.144.camel@nimitz> Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: Andrew Morton , ebmunson@us.ibm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, libhugetlbfs-devel@lists.sourceforge.net, abh@cray.com List-ID: On (04/08/08 14:10), Dave Hansen didst pronounce: > On Thu, 2008-07-31 at 11:31 +0100, Mel Gorman wrote: > > We are a lot more reliable than we were although exact quantification is > > difficult because it's workload dependent. For a long time, I've been able > > to test bits and pieces with hugepages by allocating the pool at the time > > I needed it even after days of uptime. Previously this required a reboot. > > This is also a pretty big expansion of fs/hugetlb/ use outside of the > filesystem itself. It is hacking the existing shared memory > kernel-internal user to spit out effectively anonymous memory. > > Where do we draw the line where we stop using the filesystem for this? > Other than the immediate code reuse, does it gain us anything? > > I have to think that actually refactoring the filesystem code and making > it usable for really anonymous memory, then using *that* in these > patches would be a lot more sane. Especially for someone that goes to > look at it in a year. :) > See, that's great until you start dealing with MAP_SHARED|MAP_ANONYMOUS. To get that right between children, you end up something very fs-like when the child needs to fault in a page that is already populated by the parent. I strongly suspect we end up back at hugetlbfs backing it :/ If you were going to do such a thing, you'd end up converting something like ramfs to hugetlbfs and sharing that. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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