[Xen-users] NUMA nodes and cpu layout

[Stefan Kadow <stefan.kadow@xxxxxxxxx>]

Hello,

I have installed Debian 9.4 Stretch (stable) with Xen Hypervisor 4.8
(package from repository) on a NUMA machine with two AMD Epyc processors.

When booting the default Debian kernel, the command "numactl --hardware"
returns the following:
available: 8 nodes (0-7)
node 0 cpus: 0 1 2 3 32 33 34 35
node 0 size: 0 MB
node 0 free: 0 MB
node 1 cpus: 4 5 6 7 36 37 38 39
node 1 size: 32170 MB
node 1 free: 31758 MB
node 2 cpus: 8 9 10 11 40 41 42 43
node 2 size: 0 MB
node 2 free: 0 MB
...

But when booting the Xen Kernel, the command "xl cpupool-numa-split"
returns another layout for cpus and nodes:
Name               CPU list
Pool-node0         0,1,2,3,4,5,6,7
Pool-node1         8,9,10,11,12,13,14,15
Pool-node2         16,17,18,19,20,21,22,23
...

Shouldn't the layout be the same?

I want pools of 8 cpus each, but which cpus should be combined for
optimal performance?

Solution 1) from numactl
cpus="0-3,32-35"

Solution 2) from xl cpupool-numa-split
cpus="0-7"

--
Stefan

Attachment: numactl-hardware.txt
Description: Text document

Attachment: cpupool-numa-split.txt
Description: Text document

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