9a2a1a375d
Adds some conceptual information about NUMA, and discusses how nova considers NUMA topology when booting instances. (This is a starting point, I'm happy for people to move this to a different section, or change wording). Change-Id: I328831fb3aef9531ee924aa86726277b7eac0cb5 Closes-Bug: 1369207
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1.2 KiB
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26 lines
1.2 KiB
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Consider NUMA topology when booting instances
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NUMA topology can exist on both the physical hardware of the host, and the
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virtual hardware of the instance. OpenStack Compute uses libvirt to tune
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instances to take advantage of NUMA topologies. The libvirt driver boot
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process looks at the NUMA topology field of both the instance and the host it
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is being booted on, and uses that information to generate an appropriate
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configuration.
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If the host is NUMA capable, but the instance has not requested a NUMA
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topology, Compute attempts to pack the instance into a single cell.
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If this fails, though, Compute will not continue to try.
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If the host is NUMA capable, and the instance has requested a specific NUMA
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topology, Compute will try to pin the vCPUs of different NUMA cells
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on the instance to the corresponding NUMA cells on the host. It will also
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expose the NUMA topology of the instance to the guest OS.
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If you want Compute to pin a particular vCPU as part of this process,
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set the ``vcpu_pin_set`` parameter in the :file:`nova.conf` configuration
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file. For more information about the ``vcpu_pin_set`` parameter, see the
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Configuration Reference Guide.
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