Oliver O'Halloran <ooh...@gmail.com> writes:
> When adding and removing a CPU from the system the per-cpu masks that
> are used by the scheduler to construct scheduler domains need to be updated
> to account for the cpu entering or exiting the system. Currently logic this
> is open-coded for the thread sibling mask and shared for the core mask.
"logic this is"
> This patch moves all the logic for rebuilding these masks into a single
> function and simplifies the logic which determines which CPUs are within
> a "core".
The diff is hard to read but I think it's OK. Other than ...
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index 1c531887ca51..3922cace927e 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -630,14 +630,20 @@ int cpu_first_thread_of_core(int core)
> }
> EXPORT_SYMBOL_GPL(cpu_first_thread_of_core);
>
> -static void traverse_siblings_chip_id(int cpu, bool add, int chipid)
> +static bool update_core_mask_by_chip_id(int cpu, bool add)
^
call it
onlining like below
> {
> const struct cpumask *mask = add ? cpu_online_mask : cpu_present_mask;
> + int chipid = cpu_to_chip_id(cpu);
> int i;
>
> + if (chipid == -1)
> + return false;
> +
> for_each_cpu(i, mask)
> if (cpu_to_chip_id(i) == chipid)
> set_cpus_related(cpu, i, add, cpu_core_mask);
> +
> + return true;
> }
>
> /* Must be called when no change can occur to cpu_present_mask,
> @@ -662,42 +668,72 @@ static struct device_node *cpu_to_l2cache(int cpu)
> return cache;
> }
>
> -static void traverse_core_siblings(int cpu, bool add)
> +static bool update_core_mask_by_l2(int cpu, bool onlining)
> {
> + const struct cpumask *mask = onlining ? cpu_online_mask :
> cpu_present_mask;
> struct device_node *l2_cache, *np;
> - const struct cpumask *mask;
> - int chip_id;
> int i;
>
> - /* threads that share a chip-id are considered siblings (same die) */
> - chip_id = cpu_to_chip_id(cpu);
> -
> - if (chip_id >= 0) {
> - traverse_siblings_chip_id(cpu, add, chip_id);
> - return;
> - }
> -
> - /* if the chip-id fails then group siblings by the L2 cache */
> l2_cache = cpu_to_l2cache(cpu);
> - mask = add ? cpu_online_mask : cpu_present_mask;
> + if (l2_cache == NULL)
> + return false;
> +
> for_each_cpu(i, mask) {
> np = cpu_to_l2cache(i);
> if (!np)
> continue;
>
> if (np == l2_cache)
> - set_cpus_related(cpu, i, add, cpu_core_mask);
> + set_cpus_related(cpu, i, onlining, cpu_core_mask);
>
> of_node_put(np);
> }
> of_node_put(l2_cache);
> +
> + return true;
> +}
> +
> +static void update_thread_mask(int cpu, bool onlining)
> +{
> + int base = cpu_first_thread_sibling(cpu);
> + int i;
> +
> + pr_info("CPUDEBUG: onlining cpu %d, base %d, thread_per_core %d",
> + cpu, base, threads_per_core);
That's too spammy for cpu hotplug. Make it pr_debug() at most.
cheers
