Commit 419fcdec authored by Igor Mammedov's avatar Igor Mammedov Committed by Eduardo Habkost

numa: add '-numa cpu,...' option for property based node mapping

legacy cpu to node mapping is using cpu index values to map
VCPU to node with help of '-numa node,nodeid=node,cpus=x[-y]'
option. However cpu index is internal concept and QEMU users
have to guess /reimplement qemu's logic/ to map it to
a concrete cpu socket/core/thread to make sane CPUs
placement across numa nodes.

This patch allows to map cpu objects to numa nodes using
the same properties as used for cpus with -device/device_add

At present valid properties/values to address CPUs could be
fetched using hotpluggable-cpus monitor/qmp command, it will
require user to start qemu twice when creating domain to fetch
possible CPUs for a machine type/-smp layout first and
then the second time with numa explicit mapping for actual
usage. The first step results could be saved and reused to
set/change mapping later as far as machine type/-smp stays
the same.

Proposed impl. supports exact and wildcard matching to
simplify CLI and allow to set mapping for a specific cpu
or group of cpu objects specified by matched properties.

For example:

   # exact mapping x86
   -numa cpu,node-id=x,socket-id=y,core-id=z,thread-id=n

   # exact mapping SPAPR
   -numa cpu,node-id=x,core-id=y

   # wildcard mapping, all cpu objects that match socket-id=y
   # are mapped to node-id=x
   -numa cpu,node-id=x,socket-id=y
Signed-off-by: 's avatarIgor Mammedov <>
Message-Id: <>
Reviewed-by: 's avatarDavid Gibson <>
Signed-off-by: 's avatarEduardo Habkost <>
parent 1171ae9a
......@@ -290,6 +290,21 @@ static int parse_numa(void *opaque, QemuOpts *opts, Error **errp)
goto end;
if (!object->u.cpu.has_node_id) {
error_setg(&err, "Missing mandatory node-id property");
goto end;
if (!numa_info[object->u.cpu.node_id].present) {
error_setg(&err, "Invalid node-id=%" PRId64 ", NUMA node must be "
"defined with -numa node,nodeid=ID before it's used with "
"-numa cpu,node-id=ID", object->u.cpu.node_id);
goto end;
machine_set_cpu_numa_node(ms, qapi_NumaCpuOptions_base(&object->u.cpu),
......@@ -5690,10 +5690,12 @@
# @dist: NUMA distance configuration (since 2.10)
# @cpu: property based CPU(s) to node mapping (Since: 2.10)
# Since: 2.1
{ 'enum': 'NumaOptionsType',
'data': [ 'node', 'dist' ] }
'data': [ 'node', 'dist', 'cpu' ] }
# @NumaOptions:
......@@ -5707,7 +5709,8 @@
'discriminator': 'type',
'data': {
'node': 'NumaNodeOptions',
'dist': 'NumaDistOptions' }}
'dist': 'NumaDistOptions',
'cpu': 'NumaCpuOptions' }}
# @NumaNodeOptions:
......@@ -5756,6 +5759,20 @@
'dst': 'uint16',
'val': 'uint8' }}
# @NumaCpuOptions:
# Option "-numa cpu" overrides default cpu to node mapping.
# It accepts the same set of cpu properties as returned by
# query-hotpluggable-cpus[].props, where node-id could be used to
# override default node mapping.
# Since: 2.10
{ 'struct': 'NumaCpuOptions',
'base': 'CpuInstanceProperties',
'data' : {} }
# @HostMemPolicy:
......@@ -145,10 +145,12 @@ STEXI
@item -numa node[,mem=@var{size}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}]
@itemx -numa node[,memdev=@var{id}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}]
@itemx -numa dist,src=@var{source},dst=@var{destination},val=@var{distance}
@itemx -numa cpu,node-id=@var{node}[,socket-id=@var{x}][,core-id=@var{y}][,thread-id=@var{z}]
@findex -numa
Define a NUMA node and assign RAM and VCPUs to it.
Set the NUMA distance from a source node to a destination node.
Legacy VCPU assignment uses @samp{cpus} option where
@var{firstcpu} and @var{lastcpu} are CPU indexes. Each
@samp{cpus} option represent a contiguous range of CPU indexes
(or a single VCPU if @var{lastcpu} is omitted). A non-contiguous
......@@ -162,6 +164,24 @@ a NUMA node:
-numa node,cpus=0-2,cpus=5
@end example
@samp{cpu} option is a new alternative to @samp{cpus} option
which uses @samp{socket-id|core-id|thread-id} properties to assign
CPU objects to a @var{node} using topology layout properties of CPU.
The set of properties is machine specific, and depends on used
machine type/@samp{smp} options. It could be queried with
@samp{hotpluggable-cpus} monitor command.
@samp{node-id} property specifies @var{node} to which CPU object
will be assigned, it's required for @var{node} to be declared
with @samp{node} option before it's used with @samp{cpu} option.
For example:
-M pc \
-smp 1,sockets=2,maxcpus=2 \
-numa node,nodeid=0 -numa node,nodeid=1 \
-numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
@end example
@samp{mem} assigns a given RAM amount to a node. @samp{memdev}
assigns RAM from a given memory backend device to a node. If
@samp{mem} and @samp{memdev} are omitted in all nodes, RAM is
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