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author | David Hildenbrand <david@redhat.com> | 2022-10-14 15:47:17 +0200 |
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committer | David Hildenbrand <david@redhat.com> | 2022-10-27 11:00:50 +0200 |
commit | 10218ae6d006f76410804cc4dc690085b3d008b5 (patch) | |
tree | 6b8988af01e344334811ce9041f87bc153210e52 /backends | |
parent | e2de2c497e5744bc2c009aadd0af7633f2947948 (diff) | |
download | qemu-10218ae6d006f76410804cc4dc690085b3d008b5.zip qemu-10218ae6d006f76410804cc4dc690085b3d008b5.tar.gz qemu-10218ae6d006f76410804cc4dc690085b3d008b5.tar.bz2 |
util: Add write-only "node-affinity" property for ThreadContext
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 <mprivozn@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221014134720.168738-5-david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Diffstat (limited to 'backends')
0 files changed, 0 insertions, 0 deletions