[Xen-devel] [Patch] use full-size cpumask for vcpu-pin

To:	"xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject:	[Xen-devel] [Patch] use full-size cpumask for vcpu-pin
From:	Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
Date:	Mon, 02 Aug 2010 08:40:04 +0200
Delivery-date:	Sun, 01 Aug 2010 23:40:46 -0700
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Hi,

attached patch solves a problem with vcpu-pinning and hot-plug of cpus:

If a vcpu is unpinned via

xl vcpu-pin <domain> <vcpu> all

on a system with 64 cpus and later other cpus are plugged in, this vcpu will
be restricted to the first 64 cpus of the system.

The reason is the allocation of the cpumap for pinning: the size is only for
the ACTUAL number of physical cpus in the system, not the possible number.
The solution is to allocate a cpumap for up to NR_CPUS.

Repairing xm vcpu-pin is much harder and not covered by this patch, but the
problem can be avoided by calling

xm vcpu-pin <domain> <vcpu> 0-255

instead (all is hard-wired to 0-63 now).


Juergen

--
Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 3222 2967
Fujitsu Technology Solutions              e-mail: juergen.gross@xxxxxxxxxxxxxx
Domagkstr. 28                           Internet: ts.fujitsu.com
D-80807 Muenchen                 Company details: ts.fujitsu.com/imprint.html

cpumask.patch
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[Xen-devel] [Patch] use full-size cpumask for vcpu-pin