[kernel-xen] balloon messages from latest kernel-xen

[Glenn Enright]

On 22/03/13 14:16, Steven Haigh wrote:
> On 22/03/13 08:20, Glenn Enright wrote:
>> Just following up on this, I ended up using a workaround with
>> "dom0_mem=599M,max:600M" That gives me all the allocated RAM and only
>> slightly less than maximum in action. And no error messages in the
>> kernel. It also means I don't need to mess with proc values later in the
>> boot process :).
>
> I'm a little curious here... What did 'xm info' show during this? 
> While the Dom0 kernel may have reported different memory mappings, all 
> your RAM should be visible.
>
> Depending on the effect of this, it may be worth posting this on the 
> xen-devel list to get feedback from them. Personally, I don't use 
> memory ballooning as it is not in most peoples interest to use it - 
> however it can have its benefits (although RAM is cheap and these are 
> slowly becoming moot points).
>
I agree, its a bit odd. We don't use any balloon features either, and 
that is disabled in xl.conf. I was just trying to make the kernel errors 
I originally noted go away.

If I set dom0mem=max:600 I saw all the RAM, but the kernel messages only 
went away when I did something like

   cat /sys/devices/system/xen_memory/xen_memory0/info/current_kb > \
     /sys/devices/system/xen_memory/xen_memory0/target_kb

Those proc values were close but not quite the same, target_kb was 
slightly larger beforehand.

With dom0_mem=600, xm top showed the full RAM amount, but meminfo gave a 
much smaller amount and trying to actually use that caused the kernel 
some problems. I'll see if I can work up a report for xen-devel after 
I've replicated it on some other hardware also

Best, Glenn