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RE: [Xen-devel] How much memory does a domain REALLY use...

  • To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Graham, Simon" <Simon.Graham@xxxxxxxxxxx>
  • Date: Sat, 24 Feb 2007 09:15:10 -0500
  • Delivery-date: Sat, 24 Feb 2007 06:14:32 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcdXsilmiwy4S98FTPqiaqV0JXsxkgAQHcfAAAqZ8FA=
  • Thread-topic: [Xen-devel] How much memory does a domain REALLY use...

> > . First, the biggie -- swiotlb; if I'm not mistaken, this allocates
> 64MB
> > from the domain
> >   heap (in addition to the 64MB of low memory in the domain itself).
> > Allocated with
> >   xen_create_contiguous_region in 256KB chunks.
> Xen_create_contiguous_region() gives up the existing RAM and replaces
> with a
> new contiguous extent, so it shouldn't allocate net extra memory.

Ah - missed that; thanks! So - for the swiotlb it re-allocates the 64MB
of low memory using 256KB contiguous chunks then...

> How are you determining amount of RAM used: xm info and looking at
> freemem?
> Or xm list and look at memory usage for dom0?

I'm using xenstat and looking at the difference between total memory and
free memory (which is in turn obtained from avail_domheap_pages via
xc_physinfo... Hmm - does this mean the free memory in the xen heap zone
is not included? Seems like this is pretty small though (8MB total???)


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