Re: [libvirt] [PATCH 3/3] virCaps: Expose distance between host NUMA nodes
On Mon, Jun 02, 2014 at 02:16:00PM +0200, Michal Privoznik wrote:
If user or management application wants to create a guest,
it may be useful to know the cost of internode latencies
before the guest resources are pinned. For example:
<capabilities>
<host>
...
<topology>
<cells num='2'>
<cell id='0'>
<memory unit='KiB'>4004132</memory>
<cell id='0' distance='10'/>
<cell id='1' distance='20'/>
I'd be a little more comfortable if we didn't use a <cell>
within a <cell>. Perhaps lets use 'sibling' as the name
instead and group the elements. eg could we do
<distances>
<sibling id="0" value="10"/>
<sibling id="1" value="20'/>
</distance>
</topology>
...
</host>
...
</capabilities>
we can see the distance from node1 to node0 is 20 and within nodes 10.
One thing with having the data under each <cell> is that we're
actually reporting twice as much as we need to. ie the distance
between cell N and M is reported under both N and M. A different
option would be todo reporting at the toplevel within <topology>
eg
<distances>
<siblings distance="10">
<cell id="0"/>
<cell id="1"/>
</siblings>
</distance>
I'm not sure whether doing this is worth while or not though ?
Regards,
Daniel
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