Re: [Xen-devel] RFC: Still TODO for 4.2? xl domain numa memory allocation vs xm/xend

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 20 Jan 2012, Ian Campbell wrote:
> On Thu, 2012-01-19 at 21:14 +0000, Pasi K���¤rkk���¤inen wrote:
> > On Wed, Jan 04, 2012 at 04:29:22PM +0000, Ian Campbell wrote:
> > > 
> > > Has anybody got anything else? I'm sure I've missed stuff. Are there any
> > > must haves e.g. in the paging/sharing spaces?
> > > 
> > 
> > Something that I just remembered:
> > http://wiki.xen.org/xenwiki/Xen4.1
> > 
> > "NUMA-aware memory allocation for VMs. xl in Xen 4.1 will allocate
> > equal amount of memory from every NUMA node for the VM. xm/xend
> > allocates all the memory from the same NUMA node."
> 
> I'm not that familiar with the NUMA support but my understanding was
> that memory was allocated by libxc/the-hypervisor and not by the
> toolstack and that the default was to allocate from the same numa nodes
> as domains the processor's were pinned to i.e. if you pin the processors
> appropriately the Right Thing just happens. Do you believe this is not
> the case and/or not working right with xl?

It seems that xend is retrieving numa info about the platform, see
pyxc_numainfo, then using those info to pin vcpus to pcpus, see
_setCPUAffinity.
Still it seems to me more of an hack than the right way to solve the
problem.

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