From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mick Jordan Subject: Re: Design question for PV superpage support Date: Mon, 02 Mar 2009 09:45:06 -0800 Message-ID: <49AC1B22.50307@Sun.COM> References: <200903020754.23534.dcm@mccr.org> <49AC0C96.7070608@Sun.COM> Reply-To: Mick.Jordan@sun.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7BIT Return-path: In-reply-to: <49AC0C96.7070608@Sun.COM> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Dave McCracken Cc: Xen Developers List List-Id: xen-devel@lists.xenproject.org On 03/02/09 08:43, Mick Jordan wrote: > On 03/02/09 05:54, Dave McCracken wrote: >> The solution I am working on for how to support Linux hugepages (Xen >> superpages) involves creating domains made up entirely of >> superpages. I can create a working domain with superpages and am in >> the process of supporting it in save/restore. >> >> I'm assuming that this means that everything is upgraded from 4K to 2MB. E.g. pfn 0 = 0, pfn 1 = 2MB., etc., and the mfn<->pfn maps also. > This wouldn't work too well for me in the case of thread stacks > because we need to map out parts of the stack and, although we want > large virtual stacks, we don't want do dedicate that much physical > memory. Is it really difficult to support mixed pages sizes in the > general case, e.g., save/restore etc.? Save/restore is definitely important for me and we do support it at present. I'm wondering if I might be able to "reapply" my 2MB mappings after a restore on a 4K system, given that these are just layered on a 1-1 mapping between physical/virtual for all allocated memory. Mick