David Hildenbrand <da...@redhat.com> writes:
> Let's make it easier to pin threads created via a ThreadContext to
> all host CPUs currently belonging to a given set of host NUMA nodes --
> which is the common case.
>
> "node-affinity" is simply a shortcut for setting "cpu-affinity" manually
> to the list of host CPUs belonging to the set of host nodes. This property
> can only be written.
>
> A simple QEMU example to set the CPU affinity to host node 1 on a system
> with two nodes, 24 CPUs each, whereby odd-numbered host CPUs belong to
> host node 1:
> qemu-system-x86_64 -S \
> -object thread-context,id=tc1,node-affinity=1
>
> And we can query the cpu-affinity via HMP/QMP:
> (qemu) qom-get tc1 cpu-affinity
> [
> 1,
> 3,
> 5,
> 7,
> 9,
> 11,
> 13,
> 15,
> 17,
> 19,
> 21,
> 23,
> 25,
> 27,
> 29,
> 31,
> 33,
> 35,
> 37,
> 39,
> 41,
> 43,
> 45,
> 47
> ]
>
> We cannot query the node-affinity:
> (qemu) qom-get tc1 node-affinity
> Error: Insufficient permission to perform this operation
>
> But note that due to dynamic library loading this example will not work
> before we actually make use of thread_context_create_thread() in QEMU
> code, because the type will otherwise not get registered. We'll wire
> this up next to make it work.
>
> Note that if the host CPUs for a host node change due do CPU hot(un)plug
> CPU onlining/offlining (i.e., lscpu output changes) after the ThreadContext
> was started, the CPU affinity will not get updated.
>
> Reviewed-by: Michal Privoznik <mpriv...@redhat.com>
> Acked-by: Markus Armbruster <arm...@redhat.com>
> Signed-off-by: David Hildenbrand <da...@redhat.com>
> ---
> qapi/qom.json | 9 ++++-
> util/meson.build | 2 +-
> util/thread-context.c | 84 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 93 insertions(+), 2 deletions(-)
>
> diff --git a/qapi/qom.json b/qapi/qom.json
> index 8013ba4b82..5a2db663f0 100644
> --- a/qapi/qom.json
> +++ b/qapi/qom.json
> @@ -839,10 +839,17 @@
> # threads created in the thread context (default: QEMU main
> # thread CPU affinity)
> #
> +# @node-affinity: the list of host node numbers that will be resolved to a
> list
> +# of host CPU numbers used as CPU affinity. This is a
> shortcut
> +# for specifying the list of host CPU numbers belonging to
> the
> +# host nodes manually by setting @cpu-affinity. (default:
> QEMU
> +# main thread affinity)
Would you mind breaking these lines a bit earlier, like you did for the
previous member?
> +#
> # Since: 7.2
> ##
> { 'struct': 'ThreadContextProperties',
> - 'data': { '*cpu-affinity': ['uint16'] } }
> + 'data': { '*cpu-affinity': ['uint16'],
> + '*node-affinity': ['uint16'] } }
>
>
> ##
[...]
