From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 3 Nov 2005 00:26:49 -0500 From: Jeff Dike Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 Message-ID: <20051103052649.GA16508@ccure.user-mode-linux.org> References: <1130917338.14475.133.camel@localhost> <20051102172729.9E7C.Y-GOTO@jp.fujitsu.com> <43687C3D.7060706@yahoo.com.au> <200511021728.36745.rob@landley.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200511021728.36745.rob@landley.net> Sender: owner-linux-mm@kvack.org Return-Path: To: Rob Landley Cc: Nick Piggin , user-mode-linux-devel@lists.sourceforge.net, Yasunori Goto , Dave Hansen , Ingo Molnar , Mel Gorman , "Martin J. Bligh" , Andrew Morton , kravetz@us.ibm.com, linux-mm , Linux Kernel Mailing List , lhms List-ID: On Wed, Nov 02, 2005 at 05:28:35PM -0600, Rob Landley wrote: > With fragmentation reduction and prezeroing, UML suddenly gains the option of > calling madvise(DONT_NEED) on sufficiently large blocks as A) a fast way of > prezeroing, B) a way of giving memory back to the host OS when it's not in > use. DONT_NEED is insufficient. It doesn't discard the data in dirty file-backed pages. Badari Pulavarty has a test patch (google for madvise(MADV_REMOVE)) which does do the trick, and I have a UML patch which adds memory hotplug. This combination does free memory back to the host. Jeff -- 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