Hello, In http://wiki.xensource.com/xenwiki/Xen4.0 we mention the following: "Better performance and scalability: 128 vcpus per guest, 1 TB of RAM per host, 128 physical CPUs per host (as a default, can be compile-time increased to lots more)." But what''s the max supported amount of memory for a (64bit) guest? -- Pasi _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 14/08/2010 19:42, "Pasi Kärkkäinen" <pasik@iki.fi> wrote:> Hello, > > In http://wiki.xensource.com/xenwiki/Xen4.0 we mention the following: > "Better performance and scalability: 128 vcpus per guest, 1 TB of RAM per > host, 128 physical CPUs per host (as a default, can be compile-time increased > to lots more)." > > But what''s the max supported amount of memory for a (64bit) guest?Allocating the whole 1TB should work. It''s unlikely to have been tested though. -- Keir> -- Pasi > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Pasi Kärkkäinen
2010-Aug-14 21:30 UTC
Re: [Xen-devel] Xen max supported memory per guest VM?
On Sat, Aug 14, 2010 at 10:18:11PM +0100, Keir Fraser wrote:> On 14/08/2010 19:42, "Pasi Kärkkäinen" <pasik@iki.fi> wrote: > > > Hello, > > > > In http://wiki.xensource.com/xenwiki/Xen4.0 we mention the following: > > "Better performance and scalability: 128 vcpus per guest, 1 TB of RAM per > > host, 128 physical CPUs per host (as a default, can be compile-time increased > > to lots more)." > > > > But what''s the max supported amount of memory for a (64bit) guest? > > Allocating the whole 1TB should work. It''s unlikely to have been tested > though. >Ok. I guess it might also have a difference if it''s a PV or HVM guest.. -- Pasi _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 14/08/2010 22:30, "Pasi Kärkkäinen" <pasik@iki.fi> wrote:>>> In http://wiki.xensource.com/xenwiki/Xen4.0 we mention the following: >>> "Better performance and scalability: 128 vcpus per guest, 1 TB of RAM per >>> host, 128 physical CPUs per host (as a default, can be compile-time >>> increased >>> to lots more)." >>> >>> But what''s the max supported amount of memory for a (64bit) guest? >> >> Allocating the whole 1TB should work. It''s unlikely to have been tested >> though. >> > > Ok. I guess it might also have a difference if it''s a PV or HVM guest..I can''t think of a reason we''d be limited to less for HVM or PV. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
>>> On 14.08.10 at 23:18, Keir Fraser <keir.fraser@eu.citrix.com> wrote: > On 14/08/2010 19:42, "Pasi Kärkkäinen" <pasik@iki.fi> wrote: > >> Hello, >> >> In http://wiki.xensource.com/xenwiki/Xen4.0 we mention the following: >> "Better performance and scalability: 128 vcpus per guest, 1 TB of RAM per >> host, 128 physical CPUs per host (as a default, can be compile-time increased >> to lots more)." >> >> But what''s the max supported amount of memory for a (64bit) guest? > > Allocating the whole 1TB should work. It''s unlikely to have been tested > though.Not everything will work with more than 512G: Anything that wants to access the guest''s pfn_to_mfn_frame_list_list won''t work, as there''s no specification of how more than a page worth of these top level pointers should be expressed. Affected would be (afaict) save/ restore/migrate, kexec, and dumping of a crashed guest. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 16/08/2010 10:04, "Jan Beulich" <JBeulich@novell.com> wrote:>>> But what''s the max supported amount of memory for a (64bit) guest? >> >> Allocating the whole 1TB should work. It''s unlikely to have been tested >> though. > > Not everything will work with more than 512G: Anything that wants > to access the guest''s pfn_to_mfn_frame_list_list won''t work, as > there''s no specification of how more than a page worth of these top > level pointers should be expressed. Affected would be (afaict) save/ > restore/migrate, kexec, and dumping of a crashed guest.Okay, so that''s a further restriction on PV guests. HVM guests should theoretically still be good up to 1TB. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Pasi Kärkkäinen
2010-Aug-16 09:34 UTC
Re: [Xen-devel] Xen max supported memory per guest VM?
On Mon, Aug 16, 2010 at 10:18:53AM +0100, Keir Fraser wrote:> On 16/08/2010 10:04, "Jan Beulich" <JBeulich@novell.com> wrote: > > >>> But what''s the max supported amount of memory for a (64bit) guest? > >> > >> Allocating the whole 1TB should work. It''s unlikely to have been tested > >> though. > > > > Not everything will work with more than 512G: Anything that wants > > to access the guest''s pfn_to_mfn_frame_list_list won''t work, as > > there''s no specification of how more than a page worth of these top > > level pointers should be expressed. Affected would be (afaict) save/ > > restore/migrate, kexec, and dumping of a crashed guest. > > Okay, so that''s a further restriction on PV guests. HVM guests should > theoretically still be good up to 1TB. >Ok, I updated this info to: http://wiki.xensource.com/xenwiki/Xen4.0 -- Pasi _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel