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Re: [Qemu-devel] [RFC 08/13] pc: add writeonly 'cpu' property to PCMachi
From: |
Igor Mammedov |
Subject: |
Re: [Qemu-devel] [RFC 08/13] pc: add writeonly 'cpu' property to PCMachine |
Date: |
Tue, 24 Jan 2017 11:07:38 +0100 |
On Mon, 23 Jan 2017 13:03:50 -0200
Eduardo Habkost <address@hidden> wrote:
> On Mon, Jan 23, 2017 at 12:20:33PM +0530, Bharata B Rao wrote:
> > On Thu, Jan 19, 2017 at 04:04:23PM +0100, Igor Mammedov wrote:
> > > On Wed, 18 Jan 2017 16:57:13 -0200
> > > Eduardo Habkost <address@hidden> wrote:
> > >
> > > > On Wed, Jan 18, 2017 at 06:13:24PM +0100, Igor Mammedov wrote:
> > > > > it will allow generic numa code to set cpu to numa node mapping
> > > > > in target independent manner in the next patch.
> > > > >
> > > > > Signed-off-by: Igor Mammedov <address@hidden>
> > > > > ---
> > > > > hw/i386/pc.c | 56
> > > > > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > > > > 1 file changed, 56 insertions(+)
> > > > >
> > > > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > > > > index f8ea635..1d33a5e 100644
> > > > > --- a/hw/i386/pc.c
> > > > > +++ b/hw/i386/pc.c
> > > > > @@ -2201,6 +2201,56 @@ static void pc_machine_set_pit(Object *obj,
> > > > > bool value, Error **errp)
> > > > > pcms->pit = value;
> > > > > }
> > > > >
> > > > > +static void pc_machine_set_cpu(Object *obj, Visitor *v, const char
> > > > > *name,
> > > > > + void *opaque, Error **errp)
> > > > > +{
> > > > > + uint32_t apic_id;
> > > > > + X86CPUTopoInfo topo;
> > > > > + CPUArchId *cpu_slot;
> > > > > + Error *local_err = NULL;
> > > > > + CpuInstanceProperties *cpu_props = NULL;
> > > > > + PCMachineState *pcms = PC_MACHINE(obj);
> > > > > + MachineClass *mc = MACHINE_GET_CLASS(obj);
> > > > > +
> > > > > + visit_type_CpuInstanceProperties(v, name, &cpu_props,
> > > > > &local_err);
> > > > > + if (local_err) {
> > > > > + goto out;
> > > > > + }
> > > > > +
> > > > > + if (!cpu_props->has_node_id) {
> > > > > + error_setg(&local_err, "node-id property is not specified");
> > > > > + goto out;
> > > > > + }
> > > > > +
> > > > > + /*
> > > > > + * make sure that possible_cpus is initialized
> > > > > + * as property setter might be called before machine init is
> > > > > called
> > > > > + */
> > > > > + mc->possible_cpu_arch_ids(MACHINE(obj));
> > > > > +
> > > > > + topo.pkg_id = cpu_props->socket_id;
> > > > > + topo.core_id = cpu_props->core_id;
> > > > > + topo.smt_id = cpu_props->thread_id;
> > > > > + apic_id = apicid_from_topo_ids(smp_cores, smp_threads, &topo);
> > > > > + cpu_slot = pc_find_cpu_slot(pcms, apic_id, NULL);
> > > >
> > > > If we make TYPE_MACHINE provide an API to query CPU slots, e.g.:
> > > > CPUArchId *machine_find_cpu_slot(MachineState *m,
> > > > CpuInstanceProperties *props)
> > > so if there is no objections,
> > > I'll move possible_cpus to MachineState
> > > and add to MachineClass above callback so target machine
> > > would be able to provide arch specific lookup function.
> > > it should work for both x86 and ARM.
> >
> > The need for possible_cpus in MachineState for sPAPR isn't immediately
> > apparent to me. In the context of this new numa "cpu" property, PC target
> > seems to use possible_cpus to store and later lookup the numa node id for
> > a given CPU. Wondering if that could be achieved w/o needing possible_cpus
> > in MachineState ?
>
> We need to save the node ID for not-yet-plugged CPUs somewhere,
> and the existing numa_info[].node_cpu field is cpu_index-based so
> it needs to be replaced. A MachineState field would allow us to
> do that in a generic way.
I'm trying to quickly hack SPAPR code to use possible_cpus
to show how it would be used. But using the same possible_cpus
across targets have as minimum a benefit of uniform approach
and possibly more code sharing.
- Re: [Qemu-devel] [RFC 05/13] pc: move pcms->possible_cpus init out of pc_cpus_init(), (continued)
[Qemu-devel] [RFC 07/13] pc: pass apic_id to pc_find_cpu_slot() directly so lookup could be done without CPU object, Igor Mammedov, 2017/01/18
[Qemu-devel] [RFC 09/13] numa: introduce '-numa cpu' cpu option, Igor Mammedov, 2017/01/18
[Qemu-devel] [RFC 10/13] numa: replace cpu_index_to_socket_id() with cpu_index_to_instance_props(), Igor Mammedov, 2017/01/18
[Qemu-devel] [RFC 11/13] numa: use new machine.cpu property with -numa cpus=... CLI, Igor Mammedov, 2017/01/18