That doesn't really
work with the hwloc model unfortunately. Also, when you
get to smaller objects (cores, threads, ...) there are
multiple "closest" objects at each depth.
We have one "closest" object at some depth (usually
Machine or NUMA node). If you need something higher, you
just walk the parent links. If you need something smaller,
you look at children.
Also, each I/O device isn't directly attached to such a
closest object. It's usually attached under some bridge
objects. There's a tree of hwloc PCI bus objects exactly
like you have a tree of hwloc sockets/cores/threads/etc.
At the top of the I/O tree, one (bridge) object is
attached to a regular object as explained earlier. So,
when you have a random hwloc PCI object, you get its
locality by walking up its parent link until you find a
non-I/O object (one whose cpuset isn't NULL).
hwloc/helper.h gives you hwloc_get_non_io_ancestor_obj()
to do that.
Brice
Le 09/02/2012 14:34, Ralph Castain a écrit :
Ah, okay - in that case, having the I/O
device attached to the "closest" object at each depth
would be ideal from an OMPI perspective.
On Feb 9, 2012, at 6:30 AM, Brice Goglin wrote:
The bios
usually tells you which numa location is close
to each host-to-pci bridge. So the answer is
yes.
Brice
Ralph Castain <
rhc@open-mpi.org>
a écrit :
I'm not sure I understand this
comment. A PCI device is attached to the
node, not to any specific location
within the node, isn't it? Can you
really say that a PCI device is
"attached" to a specific NUMA location,
for example?
On Feb 9, 2012, at 6:15 AM, Jeff
Squyres wrote:
That
doesn't seem too attractive from an
OMPI perspective, though. We'd want
to know where the PCI devices are
actually rooted.
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