I still don''t understand how memory management for guest OSs work. What exactly is the size given to xi_create? I mean, is it the minimum guaranteed size (if so, where is the absolute maximum set), or is it the absoulte maximum guest can use? Thanks! -- Croadria Internet usluge <http://www.croadria.com> - Web hosting (Linux & Windows), E-commerce Podrska: <http://podrska.croadria.com> Tel: 01/4657 818, 01/4655 601 Fax: 01/4657 819 ------------------------------------------------------- This SF.Net email sponsored by: ApacheCon 2003, 16-19 November in Las Vegas. Learn firsthand the latest developments in Apache, PHP, Perl, XML, Java, MySQL, WebDAV, and more! http://www.apachecon.com/ _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
On Wed, Nov 12 03 at 12:55:04PM +0100, Tvrtko A. Ur?ulin wrote:> What exactly is the size given to xi_create? I mean, is it the minimum > guaranteed size (if so, where is the absolute maximum set), or is it the > absoulte maximum guest can use?Both. The guest can never have more than the size given, but it''s also guarenteed that the guest will get that much on startup. If the guest voluntarily releases memory later using the balloon driver, then it is not guarenteed to be able to get it *back* (and can''t take back more than it gave away in any case). -- Torne Wuff torne@wolfpuppy.org.uk ------------------------------------------------------- This SF.Net email sponsored by: ApacheCon 2003, 16-19 November in Las Vegas. Learn firsthand the latest developments in Apache, PHP, Perl, XML, Java, MySQL, WebDAV, and more! http://www.apachecon.com/ _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
> > I still don''t understand how memory management for guest OSs work. > > What exactly is the size given to xi_create? I mean, is it the minimum > guaranteed size (if so, where is the absolute maximum set), or is it the > absoulte maximum guest can use?When the guest Linux boots, it sizes and initialises it''s mem_map array based on the number of pages that are available to it at startup. Thus, it effectively determines the maximum size of memory that the domain can ever have (we could in principle use the new Linux support for "hot swappable" memory to enable the mem_map array to be extended, but we''ve yet to do this and aren''t keen). What might be a sensible improvement to the current tools would be the ability to be able to start a domain with less memory than its maximum size. We could do this by having the balloon driver grab frames very early in the boot sequence, before the domain adds them to its free list. This is something to consider when we update the tools for controlling the balloon driver. Ian ------------------------------------------------------- This SF.Net email sponsored by: ApacheCon 2003, 16-19 November in Las Vegas. Learn firsthand the latest developments in Apache, PHP, Perl, XML, Java, MySQL, WebDAV, and more! http://www.apachecon.com/ _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Hi, From: Ian Pratt <Ian.Pratt@cl.cam.ac.uk> Subject: Re: [Xen-devel] Memory question (again) Date: Wed, 12 Nov 2003 14:32:49 +0000> When the guest Linux boots, it sizes and initialises it''s mem_map > array based on the number of pages that are available to it at > startup. Thus, it effectively determines the maximum size of > memory that the domain can ever have (we could in principle use > the new Linux support for "hot swappable" memory to enable the > mem_map array to be extended, but we''ve yet to do this and aren''t > keen).Linux Hotplug Memory Support project might interest you. https://sourceforge.net/projects/lhms/ If I recall correctly, it handles only highmem. It''s very difficult to "hotswap" the dma and normal zones of memory due to the Linux VM architecture mapping physical memory to the kernel address space straightforwardly. -- tomo ------------------------------------------------------- This SF.Net email sponsored by: ApacheCon 2003, 16-19 November in Las Vegas. Learn firsthand the latest developments in Apache, PHP, Perl, XML, Java, MySQL, WebDAV, and more! http://www.apachecon.com/ _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel