On Wed, Mar 07, 2012 at 09:55:16PM +0800, Osier Yang wrote:
numad is an user-level daemon that monitors NUMA topology and processes resource consumption to facilitate good NUMA resource alignment of applications/virtual machines to improve performance and minimize cost of remote memory latencies. It provides a pre-placement advisory interface, so significant processes can be pre-bound to nodes with sufficient available resources.
More details: http://fedoraproject.org/wiki/Features/numad
"numad -w ncpus:memory_amount" is the advisory interface numad provides currently.
This patch add the support by introducing a bool XML element: <numatune> <autonuma/> </numatune>
If it's specified, the number of vcpus and the current memory amount specified in domain XML will be used for numad command line (numad uses MB for memory amount): numad -w $num_of_vcpus:$current_memory_amount / 1024
The advisory nodeset returned from numad will be used to set domain process CPU affinity then. (e.g. qemuProcessInitCpuAffinity).
If the user specifies both CPU affinity policy (e.g. (<vcpu cpuset="1-10,^7,^8">4</vcpu>) and XML indicating to use numad for the advisory nodeset, the specified CPU affinity will be ignored.
I'm not sure that's a good idea. When we do dynamic generation of parts of libvirt XML, we tend to report in the XML what was generated, and if 2 parts contradict each other we shouldn't silently ignore it. eg, with VNC with autoport=yes we then report the generated port number. Similarly with <cpu> mode=host, we then report what the host CPU features were. So, if we want to auto-set placement for a guest we should likely do this via the <vcpu> element eg, Current mode where placement is completely static - Input XML: <vcpu placement="static" cpuset="1-10" /> - Output XML: <vcpu placement="static" cpuset="1-10" /> Or where we want to use numad: - Input XML: <vcpu placement="auto"/> - Output XML: <vcpu placement="auto" cpuset="1-10" /> The current numad functionality you propose only sets the initial guest placement. Are we likely to have a mode in the future where numad will be called to update the placement periodically for existing guests ? If so, then "placement" would need to have more enum values. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|