From: "Jan Beulich" <JBeulich@novell.com>
To: andre.przywara@amd.com
Cc: xen-devel@lists.xensource.com
Subject: Ping: c/s 20526 (tools: avoid cpu over-commitment if numa=on)
Date: Wed, 13 Jan 2010 08:15:08 +0000 [thread overview]
Message-ID: <4B4D8F1C02000078000299EC@vpn.id2.novell.com> (raw)
Andre,
I'm afraid this change isn't really correct:
>+ cores_per_node = info['nr_cpus'] / info['nr_nodes']
>+ nodes_required = (self.info['VCPUs_max'] + cores_per_node - 1) / cores_per_node
Simply using cores_per_node (as calculated here) as a divisor is bound
to cause division-by-zero issues, namely when limiting the number of
CPUs on the Xen command line (maxcpus=). I'm not sure though, what
a reasonable solution to this might look like, since cores-per-node is
a meaningless thing in an artificial setup like this, and may also be
meaningless in asymmetric configurations. So perhaps we really need
to iterate over nodes while summing up the number of CPUs they
have until the number of needed vCPU-s was reached.
Jan
next reply other threads:[~2010-01-13 8:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-13 8:15 Jan Beulich [this message]
2010-01-13 8:29 ` Ping: c/s 20526 (tools: avoid cpu over-commitment if numa=on) Keir Fraser
2010-01-13 14:24 ` Andre Przywara
2010-01-13 22:10 ` [PATCH] NUMA: Fix computation of needed nodes Andre Przywara
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