[PATCH] xend: NUMA: fix division by zero on unpopulated nodes

[PATCH] xend: NUMA: fix division by zero on unpopulated nodes

[Andre Przywara]

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Hi,

nodes without memory will currently be disabled by also moving the 
physical cores connected to them to other nodes. This leads to nodes 
without CPUs and thus to a division by zero in the node allocation 
algorithm.
Attached patch fixes this by checking for 0 before the division. This 
fixes domain creation on boxes with memory-less nodes.
The resulting domain distribution is still not correct, I will send 
another patch after more testing.

Regards,
Andre.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>

-- 
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 488-3567-12
----to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Andrew Bowd; Thomas M. McCoy; Giuliano Meroni
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

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diff -r e406e3451835 tools/python/xen/xend/XendDomainInfo.py
--- a/tools/python/xen/xend/XendDomainInfo.py	Thu Jan 14 10:14:17 2010 +0000
+++ b/tools/python/xen/xend/XendDomainInfo.py	Thu Jan 14 15:16:28 2010 +0100
@@ -2709,9 +2709,12 @@
                                     nodeload[i] += 1
                                     break
                 for i in range(0, nr_nodes):
-                    nodeload[i] = int(nodeload[i] * 16 / len(info['node_to_cpu'][i]))
-                    if len(info['node_to_cpu'][i]) == 0 or i not in node_list:
-                        nodeload[i] += 8
+                    if len(info['node_to_cpu'][i]) == 0:
+                    	nodeload[i] += 8
+                    else:
+                        nodeload[i] = int(nodeload[i] * 16 / len(info['node_to_cpu'][i]))
+                        if i not in node_list:
+                            nodeload[i] += 8
                 return map(lambda x: x[0], sorted(enumerate(nodeload), key=lambda x:x[1]))
 
             info = xc.physinfo()

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