On Fri, Jul 08, 2016 at 13:54:58 +0200, Igor Mammedov wrote:
> On Thu, 7 Jul 2016 17:17:14 +0200
> Peter Krempa <pkre...@redhat.com> wrote:
>
> > Add a helper that looks up the NUMA node for a given CPU and use it to
> > fill the node_id in the PPC and X86 impls of query-hotpluggable-cpus.
> >
> > Signed-off-by: Peter Krempa <pkre...@redhat.com>
> > ---
> > hw/i386/pc.c | 7 +++++++
> > hw/ppc/spapr.c | 8 ++++++--
> > include/sysemu/numa.h | 1 +
> > numa.c | 13 +++++++++++++
> > 4 files changed, 27 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index 4ba02c4..a0b9507 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -2115,6 +2115,7 @@ static HotpluggableCPUList
> > *pc_query_hotpluggable_cpus(MachineState *machine)
> > HotpluggableCPUList *head = NULL;
> > PCMachineState *pcms = PC_MACHINE(machine);
> > const char *cpu_type;
> > + int node_id;
> >
> > cpu = pcms->possible_cpus->cpus[0].cpu;
> > assert(cpu); /* BSP is always present */
> > @@ -2138,6 +2139,12 @@ static HotpluggableCPUList
> > *pc_query_hotpluggable_cpus(MachineState *machine)
> > cpu_props->core_id = topo.core_id;
> > cpu_props->has_thread_id = true;
> > cpu_props->thread_id = topo.smt_id;
> > +
> > + if ((node_id = numa_node_get_by_cpu_index(i)) >= 0) {
> > + cpu_props->has_node_id = true;
> > + cpu_props->node_id = node_id;
> > + }
> I've not included node_id for a reason,
> "-numa cpus=1,2,3..." looks to me hopelessly broken now but
> I've not came up with an idea how to redo it in nice and clean way yet.
>
> Alternative could be CLI-less numa configuration, where QEMU is started
> without "-numa cpus" but with "-S" then mgmt could call
> query_hotpluggable_cpus() to get possible CPUs and then
> map them to numa nodes with a new QMP command using attributes
> it got from query_hotpluggable_cpus().
I think this could work for libvirt. The CPU index we currently expose
in the XML would become just a libvirt internal detail and the new QMP
command would be used to do the setup. Adding some QMP calls during VM
startup is okay.
> it's along the way start QEMU -smp 1,maxcpus=X and then add
> remaining CPUs with device_add after getting properties from
> query_hotpluggable_cpus().
I'm going to use a similar approach even for the hotpluggable cpus so I
can query the data for a new VM. On the other hand I can't make libvirt
use the approach with -smp 1,... all the time since we guarantee that a
XML that worked on a older version will be migratable back to the older
version.
> then at machine_done time we can adjust DT/ACPI data to reflect
> configured mapping.
In such case this series can be dropped since it provides what I need
differently.
Thanks,
Peter
