[ILUG] xen and freeing up RAM

[Conor Wynne]

On Tue, Apr 15, 2008 at 12:38 PM, Stephen Burke <steviewdr at skynet.ie> wrote:

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> On Tue, 15 Apr 2008, Conor Wynne wrote:
>
> > If I xm create the vm, then it uses that same memory again. If I xm
> > destroy
> > it, then create a NEW vm, more memory is taken away.
> > It doesn't seen right to me...
> >
>
> I remember seeing the exact same thing. AFAIR if you keep destroying and
> creating the VMs it will not run out of memory. It might appear to use more
> memory. I take it you were using "xm top" where you saw the memory
> decreasing for dom0 evertime you destroyed and created a vm?
>
> I wouldnt worry too much about it, unless it does eat up and not release
> the memory. If you set the dom0_mem in the menu.lst xm top and free will
> correctly report the memory been used dom0.


Rebooted the server, 8GB installed.
On a fresh reboot, free -m reports:

free -m
Total 7484, Free 7066

xm create one RHEL5 and one RHEL4 VM's
free -m reports:
Total 6961, Free 6530

Now xm destroy both vm's:
Total 6961, Free 6529

So where is the RAM gone?
Does this only occur on RHEL5.x?

Anyone else experienced this before?
If I restart xend the RAM is still gone.



>
>
> Just a last note about putting dom0_mem into grub/menu.lst, when you
> upgrade to a new kernel, this entry will be removed. If anyone knows how to
> correctly keep this boot option between upgrades, it would be good to know.


That is strange. Normally all kernel paramaters are kept.


>
>
> Rgds,
> Steve Burke
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Conor.