Re: [Qemu-devel] [PATCH v3 17/18] numa: add '-numa cpu, ...' option for property based node mapping

[David Gibson]

On Wed, May 10, 2017 at 01:30:01PM +0200, Igor Mammedov wrote:
> 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
> (socket-id/core-id/thread-id/node-id).
> 
> 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: Igor Mammedov <address@hidden>

Reviewed-by: David Gibson <address@hidden>

> ---
> v3:
>   - use qapi_NumaCpuOptions_base() instead of copying fields manually
>     (Eduardo)
> v2:
>   - use new NumaCpuOptions instead of CpuInstanceProperties in
>     NumaOptions, so that in future we could decouple both
>     if needed. (Eduardo Habkost <address@hidden>)
>   - clarify effect of NumaCpuOptions.node-id in qapi-schema.json
> ---
>  numa.c           | 15 +++++++++++++++
>  qapi-schema.json | 21 +++++++++++++++++++--
>  qemu-options.hx  | 20 ++++++++++++++++++++
>  3 files changed, 54 insertions(+), 2 deletions(-)
> 
> diff --git a/numa.c b/numa.c
> index ca122cc..84ce2af 100644
> --- a/numa.c
> +++ b/numa.c
> @@ -290,6 +290,21 @@ static int parse_numa(void *opaque, QemuOpts *opts, 
> Error **errp)
>              goto end;
>          }
>          break;
> +    case NUMA_OPTIONS_TYPE_CPU:
> +        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),
> +                                  &err);
> +        break;
>      default:
>          abort();
>      }
> diff --git a/qapi-schema.json b/qapi-schema.json
> index f1bcebe..c9fdbc3 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -5684,10 +5684,12 @@
>  #
>  # @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:
> @@ -5701,7 +5703,8 @@
>    'discriminator': 'type',
>    'data': {
>      'node': 'NumaNodeOptions',
> -    'dist': 'NumaDistOptions' }}
> +    'dist': 'NumaDistOptions',
> +    'cpu': 'NumaCpuOptions' }}
>  
>  ##
>  # @NumaNodeOptions:
> @@ -5751,6 +5754,20 @@
>     '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:
>  #
>  # Host memory policy types
> diff --git a/qemu-options.hx b/qemu-options.hx
> index cfe4dc3..731f1bd 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -145,10 +145,12 @@ STEXI
>  @item -numa 
> node[,address@hidden,address@hidden@var{lastcpu}]][,address@hidden
>  @itemx -numa 
> node[,address@hidden,address@hidden@var{lastcpu}]][,address@hidden
>  @itemx -numa dist,address@hidden,address@hidden,address@hidden
> address@hidden -numa 
> cpu,address@hidden,address@hidden,address@hidden,address@hidden
>  @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
>  
> address@hidden 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
> address@hidden monitor command.
> address@hidden 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:
> address@hidden
> +-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
> address@hidden 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

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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