Re: (XEN) page_alloc.c:1148:d0 Over-allocation for domain 0: 694017 > 694016

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

> How would that be? 2711MiB = 2776064kiB, which 446k off the value
> above. And apart from that, the value above isn't even divisible by 4

I messed up on that. Redid the numbers and I was off.

> (i.e. not an even number of pages).

To make this a bit easier I used 'dom0_max=max:3G', which means
(with this swiss-cheese type E820 on this Intel box):

[    0.000000] Released 75745 pages of unused memory

so I should have 75745 pages left to play with. But what I found is that
I can only go up to 786415 which is 17 pages short of the 786432 goal.

Here are the steps:

$cat `find /sys -name current_kb`
2842816
$echo $((3*1024*1024))
3145728
$echo "3145728" > `find /sys -name target_kb`
$cat `find /sys -name current_kb`
3145660
$xl dmesg | tail
(XEN) page_alloc.c:1148:d0 Over-allocation for domain 0: 786433 (786432) > 786432
(XEN) memory.c:133:d0 Could not allocate order=0 extent: id=0 memflags=0 (0 of 17)

> > Any ideas of what that might be? Could it be the shared_info, hypercall page,
> > start_info, xenconsole and some other ones are the magic 6 pages which
> > inhibit how much we can balloon up to?
> 
> Not likely: The hypercall page is in kernel (image) memory, and there's
> no console page at all fro Dom0.

17 pages.. Hmm
> 
> Jan