> >
> > While here, fix a problem where of_node_put could be called even when
> > of_get_cpu_node was not successful.
>
> of_node_put() handles NULL arguments, so this should not be necessary.
>
Ok
> > @@ -875,7 +908,7 @@ void __init mem_topology_setup(void)
> > reset_numa_cpu_lookup_table();
> >
> > for_each_present_cpu(cpu)
> > - numa_setup_cpu(cpu);
> > + numa_setup_cpu(cpu, false);
> > }
>
> I'm open to other points of view here, but I would prefer two separate
> functions, something like vphn_get_nid() for runtime and
> vphn_get_nid_early() (which could be __init) for boot-time
> initialization. Propagating a somewhat unexpressive boolean flag through
> two levels of function calls in this code is unappealing...
>
Somehow not convinced that we need to duplicate function just to avoid
passing a bool.
If propagating a boolean flag in two levels of function calls is an issue,
we could decipher the logic in numa_setup_cpu itself
Something like this
static int numa_setup_cpu(unsigned long lcpu, bool get_hwid)
{
....
if (firmware_has_feature(FW_FEATURE_VPHN)) {
long hwid;
if (get_hwid)
hwid = get_hard_smp_processor_id(cpu);
else
hwid = cpu_to_phys_id[cpu];
nid = vphn_get_nid(lcpu, hwid);
}
....
Would this help?
> Regardless, I have an annoying question :-) Isn't it possible that,
> while Linux is calling vphn_get_nid() for each logical cpu in sequence,
> the platform could change a virtual processor's node assignment,
> potentially causing sibling threads to get different node assignments
> and producing an incoherent topology (which then leads to sched domain
> assertions etc)?
>
Right, its certainly possible for node assignment to change while we iterate
through the siblings. Do you have an recommendations?
> If so, I think more care is needed. The algorithm should make the vphn
> call only once per cpu node, I think?
I didn't get "once per cpu node", How do we know which all cpus are part of
that cpu node? Or did you mean once per cpu core?
--
Thanks and Regards
Srikar Dronamraju
