Re: [Xen-devel] questions about ballooning

[Daniel Stodden <stodden@xxxxxxxxxx>]

On Sun, 2007-11-04 at 18:19 +0100, Daniel Stodden wrote:
> On Sun, 2007-11-04 at 17:17 +0000, Keir Fraser wrote:
> > 
> > 
> > On 4/11/07 17:04, "Daniel Stodden" <stodden@xxxxxxxxxx> wrote:
> > 
> > > not sure about how this bootstraps in the balloon. e.g. i'm not sure
> > > whether the whole initial memory is allocated and then returned again
> > > only upon demand. or if the initial reservation is full memory and then
> > > only grown by the balloon. i believe the former is the case. maybe
> > > someone else can comment (please).
> > 
> > The arch-specific code (setup-xen.c) sets up a mem_map big enough for
> > maximum memory ever allocatable to this domain. 'Empty pages', which are not
> > populated with RAM by the initial reservation, are detected by the balloon
> > driver when it initialises. These empty pages are filled with RAM by the
> > balloon driver on demand, if it detects that the memory target is raised.
> 
> thanks.
> 
> that helped, even despite me screwing 'full' and 'initial' while asking.

while you are at it, from xmdomain.cfg(5)

memory:
        Xen does not support overcommit of memory, so the total memory 
        of all guests (+ 64 MB needed for Xen) must be less than or 
        equal to the physical RAM in the machine.

'memory' is mem_map size, right? is this outdated or simply not true, or
am i missing something?

thanks,
daniel

-- 
Daniel Stodden
LRR     -      Lehrstuhl fÃr Rechnertechnik und Rechnerorganisation
Institut fÃr Informatik der TU MÃnchen             D-85748 Garching
http://www.lrr.in.tum.de/~stodden         mailto:stodden@xxxxxxxxxx
PGP Fingerprint: F5A4 1575 4C56 E26A 0B33  3D80 457E 82AE B0D8 735B



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