[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Bug#591836: linux-image-2.6.32-5-xen-686: support to PAE doesn't



Eriberto wrote:
> If I have 8 GB e.g. and if I do free -m and I see 3 GB, can I setup a
> DomU with 6 GB???

"free -m" shows the amount of free memory which domain 0 has. The total
amount of memory which domain 0 sees may be (considerably) smaller than
what is present in the host the remainder can be allocated to other
domU. Hence "free -m" is not a good indication of how much spare memory
remains.

IIRC then "xm physinfo" or "xl info" will show the total amount of free
host memory.

If "free -m" shows 3GB then (total guess work) domain 0 has 4GB assigned
which would mean that the remaining 4GB is available for use by domU.
You could also choose to balloon domain 0 down by e.g. another 2GB
(since you have 3GB free) which would leave a total 6GB available for
domU.

Please provide both hypervisor and kernel logs as requested by Bastian.

One common pitfall is that with a pvops domain 0 kernel the memory
covered by the PCI hole is given back to Xen and not reclaimed by domain
0. This means that if domain 0 has 4GB and there is a 0.5GB PCI hole
that domain 0 may only see 3.5GB, however the space 0.5GB will still be
available to allocate to domU. (on newer pvops kernels dom0 could be
ballooned up to regain this memory but IIRC this is not possible with
the version in squeeze).

Ian.
-- 
Ian Campbell
Current Noise: Angelcorpse - Into The Storm Of Steel

Why does New Jersey have more toxic waste dumps and California have
more lawyers?

New Jersey had first choice.




Reply to: