On Mon, 8 May 2017 15:40:04 +1000
David Gibson <da...@gibson.dropbear.id.au> wrote:
> On Wed, May 03, 2017 at 02:57:17PM +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 <imamm...@redhat.com>
> > ---
> > v2:
> > - use new NumaCpuOptions instead of CpuInstanceProperties in
> > NumaOptions, so that in future we could decouple both
> > if needed. (Eduardo Habkost <ehabk...@redhat.com>)
> > - clarify effect of NumaCpuOptions.node-id in qapi-schema.json
> > ---
> > numa.c | 25 +++++++++++++++++++++++++
> > qapi-schema.json | 21 +++++++++++++++++++--
> > qemu-options.hx | 23 ++++++++++++++++++++++-
> > 3 files changed, 66 insertions(+), 3 deletions(-)
> >
> > diff --git a/numa.c b/numa.c
> > index 40e9f44..61521f5 100644
> > --- a/numa.c
> > +++ b/numa.c
> > @@ -227,6 +227,7 @@ static int parse_numa(void *opaque, QemuOpts *opts,
> > Error **errp)
> > NumaOptions *object = NULL;
> > MachineState *ms = opaque;
> > Error *err = NULL;
> > + CpuInstanceProperties cpu;
> >
> > {
> > Visitor *v = opts_visitor_new(opts);
> > @@ -246,6 +247,30 @@ static int parse_numa(void *opaque, QemuOpts *opts,
> > Error **errp)
> > }
> > nb_numa_nodes++;
> > 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;
> > + }
> > +
> > + memset(&cpu, 0, sizeof(cpu));
> > + cpu.has_node_id = object->u.cpu.has_node_id;
> > + cpu.node_id = object->u.cpu.node_id;
> > + cpu.has_socket_id = object->u.cpu.has_socket_id;
> > + cpu.socket_id = object->u.cpu.socket_id;
> > + cpu.has_core_id = object->u.cpu.has_core_id;
> > + cpu.core_id = object->u.cpu.core_id;
> > + cpu.has_thread_id = object->u.cpu.has_thread_id;
> > + cpu.thread_id = object->u.cpu.thread_id;
> > +
> > + machine_set_cpu_numa_node(ms, &cpu, &err);
>
> It's possible I've confused myself by not looking at this whole series
> at once.
>
> But, would it be possible to make a single machine hook which maps a
> constructed cpu property set to a "canonical" cpu property set from
> the table of CPU slots (or errors, of course). That would let you do
> what you need here, and I suspect in other places, without multiple
> hooks.
Not sure that get question.
if it's about machine_set_cpu_numa_node() than it's a single generic
setter of MachineState::possible_cpus(node-id) from non machine code
and the only place it's supposed to be used is from numa configuration
code. I don't see any need to reuse it for something/somewhere else
so far.
More over it's not 1:1 mapping wrt input:affected slots,
it's 1:[1-n] where input could affect multiple slots.
I think I've tried to get machine return a list of cpu slots
and then deal with them in numa.c but result looked messy and
not to my liking.
Eventually I stopped on machine_set_cpu_numa_node() variant
as the cleanest for now.
