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Re: [Xen-users] settinjg dom0 memory, where did I go wrong?

  • To: xen-users@xxxxxxxxxxxxx
  • From: Alexandre Kouznetsov <alk@xxxxxxxxxx>
  • Date: Fri, 03 Aug 2012 11:02:09 -0500
  • Delivery-date: Fri, 03 Aug 2012 16:03:08 +0000
  • List-id: Xen user discussion <xen-users.lists.xen.org>


El 02/08/12 23:48, Michael Egglestone escribió:
Here is my /etc/default/grub

/GRUB_CMDLINE_XEN_DEFAULT="dom0_mem=4096M dom0_vcpus_pin"/
I've updated grub to populate /boot/grub/grub.cfg and then rebooted.
This two stepas are the only relevant ones to achieve the Dom0 memory restriction.

While booting, you should have interacted with Grub, checking if the parameter dom0_mem is really present in the right place. There you would probably find that it is not.

The variable used to set Dom0 memory is slightly different:

Piece of advice: don't set dom0_mem as "round" n*2^10. Subtract at least 64MB from it. Hypervisor itself need some RAM, some bit less than 64MB in Xen 4.0 case.

So, after you assign, let's say, 4032MB to Dom0 and another 64MB was eaten by hypervisor, you may consider you have "(your total RAM) - 4GB" free, available for DomU's, round 28GB in your case. Otherwise, you would have available "(your total RAM) - 4GB - (little more piece)", which will left with a "not round" amount of available RAM, near 27.94 GB in your case.

This is far from being mandatory, but brings simplicity to estimations and some bit of esthetics.

Alexandre Kouznetsov

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