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Re: [Qemu-ppc] [Qemu-devel] [PATCH v2 03/24] hw/arm/virt: use machine->p
From: |
Igor Mammedov |
Subject: |
Re: [Qemu-ppc] [Qemu-devel] [PATCH v2 03/24] hw/arm/virt: use machine->possible_cpus for storing possible topology info |
Date: |
Thu, 4 May 2017 14:55:09 +0200 |
On Thu, 4 May 2017 11:38:22 +0200
Andrew Jones <address@hidden> wrote:
> On Wed, May 03, 2017 at 02:56:57PM +0200, Igor Mammedov wrote:
> > for now precalculate and store mp_afinity in possible_cpus
> > as ARM cpus don't have socket/core/thread-id properties yet.
> > In follow patches possible_cpus will be used for storing
> > and setting NUMA node mapping and replace legacy bitmap
> > based numa_info[node_id].node_cpu/numa_get_node_for_cpu()
> >
> > For the lack of better idea, this patch cannibalizes
> > possible_cpus.cpus[x].props.thread_id so that
> > *_cpu_index_to_props() callback could return addressable
> > by props CPU which will be used by machine_set_cpu_numa_node()
> > in follow up patches to assign a CPU to node. But
> > cannibalizing is fine for now as that thread_id isn't exposed
> > to users (no hotpluggable_cpus callback support for ARM yet)
> > and it will be used only internally until 'device_add cpu'
> > is supported where we can decide on which properties to use.
> >
> > Signed-off-by: Igor Mammedov <address@hidden>
> > ---
> > v2:
> > (Drew)
> > - discarding result of possible_cpu_arch_ids() makes
> > call not obvious and is confusing. Instead assign
> > possible_cpu_arch_ids() result to local var and use
> > it instead of direct access to machine->possible_cpus
> > field, as it's done in pc.c
> > ---
> > hw/arm/virt.c | 40 +++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 37 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> > index 61ae437..e2c5626 100644
> > --- a/hw/arm/virt.c
> > +++ b/hw/arm/virt.c
> > @@ -1221,6 +1221,8 @@ static void machvirt_init(MachineState *machine)
> > {
> > VirtMachineState *vms = VIRT_MACHINE(machine);
> > VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(machine);
> > + MachineClass *mc = MACHINE_GET_CLASS(machine);
> > + const CPUArchIdList *possible_cpus;
> > qemu_irq pic[NUM_IRQS];
> > MemoryRegion *sysmem = get_system_memory();
> > MemoryRegion *secure_sysmem = NULL;
> > @@ -1344,10 +1346,16 @@ static void machvirt_init(MachineState *machine)
> > exit(1);
> > }
> >
> > - for (n = 0; n < smp_cpus; n++) {
> > - Object *cpuobj = object_new(typename);
> > + possible_cpus = mc->possible_cpu_arch_ids(machine);
> > + for (n = 0; n < possible_cpus->len; n++) {
> > + Object *cpuobj;
> >
> > - object_property_set_int(cpuobj, virt_cpu_mp_affinity(vms, n),
> > + if (n >= smp_cpus) {
> > + break;
> > + }
>
> Why the break instead of just looping 'n < smp_cpus' like x86 does? Is
> there some future work where looping up to possible_cpus->len (aka
> max_cpus) is what we'll eventually want? If so, then we need a TODO
> comment here. If not, then we should clean this up by removing the break.
There is no plans to loop here upto possible_cpus->len.
It seemed to me more consistent/safer to use index limited
by possible_cpus->len to index possible_cpus->cpus[n] array
than index limited by smp_cpus though the former currently is
always less than smp_cpus.
If you prefer 'n < smp_cpus' loop, then I can switch to it.
>
> Thanks,
> drew
>
> > +
> > + cpuobj = object_new(typename);
> > + object_property_set_int(cpuobj, possible_cpus->cpus[n].arch_id,
> > "mp-affinity", NULL);
> >
> > if (!vms->secure) {
> > @@ -1527,6 +1535,31 @@ static void virt_set_gic_version(Object *obj, const
> > char *value, Error **errp)
> > }
> > }
> >
> > +static const CPUArchIdList *virt_possible_cpu_arch_ids(MachineState *ms)
> > +{
> > + int n;
> > + VirtMachineState *vms = VIRT_MACHINE(ms);
> > +
> > + if (ms->possible_cpus) {
> > + assert(ms->possible_cpus->len == max_cpus);
> > + return ms->possible_cpus;
> > + }
> > +
> > + ms->possible_cpus = g_malloc0(sizeof(CPUArchIdList) +
> > + sizeof(CPUArchId) * max_cpus);
> > + ms->possible_cpus->len = max_cpus;
> > + for (n = 0; n < ms->possible_cpus->len; n++) {
> > + ms->possible_cpus->cpus[n].arch_id =
> > + virt_cpu_mp_affinity(vms, n);
> > + ms->possible_cpus->cpus[n].props.has_thread_id = true;
> > + ms->possible_cpus->cpus[n].props.thread_id = n;
> > +
> > + /* TODO: add 'has_node/node' here to describe
> > + to which node core belongs */
> > + }
> > + return ms->possible_cpus;
> > +}
> > +
> > static void virt_machine_class_init(ObjectClass *oc, void *data)
> > {
> > MachineClass *mc = MACHINE_CLASS(oc);
> > @@ -1543,6 +1576,7 @@ static void virt_machine_class_init(ObjectClass *oc,
> > void *data)
> > mc->pci_allow_0_address = true;
> > /* We know we will never create a pre-ARMv7 CPU which needs 1K pages */
> > mc->minimum_page_bits = 12;
> > + mc->possible_cpu_arch_ids = virt_possible_cpu_arch_ids;
> > }
> >
> > static const TypeInfo virt_machine_info = {
> > --
> > 2.7.4
> >
>
[Qemu-ppc] [PATCH v2 04/24] hw/arm/virt: explicitly allocate cpu_index for cpus, Igor Mammedov, 2017/05/03
[Qemu-ppc] [PATCH v2 05/24] numa: move source of default CPUs to NUMA node mapping into boards, Igor Mammedov, 2017/05/03
Re: [Qemu-ppc] [PATCH v2 05/24] numa: move source of default CPUs to NUMA node mapping into boards, Eduardo Habkost, 2017/05/03