On Tue, Jul 14, 2020 at 10:06:22AM +0530, Srikar Dronamraju wrote:
> Add percpu coregroup maps and masks to create coregroup domain.
> If a coregroup doesn't exist, the coregroup domain will be degenerated
> in favour of SMT/CACHE domain.
>
> Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
> Cc: Michael Ellerman <micha...@au1.ibm.com>
> Cc: Nick Piggin <npig...@au1.ibm.com>
> Cc: Oliver OHalloran <olive...@au1.ibm.com>
> Cc: Nathan Lynch <nath...@linux.ibm.com>
> Cc: Michael Neuling <mi...@linux.ibm.com>
> Cc: Anton Blanchard <an...@au1.ibm.com>
> Cc: Gautham R Shenoy <e...@linux.vnet.ibm.com>
> Cc: Vaidyanathan Srinivasan <sva...@linux.ibm.com>
> Signed-off-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
> ---
> arch/powerpc/include/asm/topology.h | 10 ++++++++
> arch/powerpc/kernel/smp.c | 37 +++++++++++++++++++++++++++++
> arch/powerpc/mm/numa.c | 5 ++++
> 3 files changed, 52 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/topology.h
> b/arch/powerpc/include/asm/topology.h
> index 2db7ba789720..34812c35018e 100644
> --- a/arch/powerpc/include/asm/topology.h
> +++ b/arch/powerpc/include/asm/topology.h
> @@ -98,6 +98,7 @@ extern int stop_topology_update(void);
> extern int prrn_is_enabled(void);
> extern int find_and_online_cpu_nid(int cpu);
> extern int timed_topology_update(int nsecs);
> +extern int cpu_to_coregroup_id(int cpu);
> #else
> static inline int start_topology_update(void)
> {
> @@ -120,6 +121,15 @@ static inline int timed_topology_update(int nsecs)
> return 0;
> }
>
> +static inline int cpu_to_coregroup_id(int cpu)
> +{
> +#ifdef CONFIG_SMP
> + return cpu_to_core_id(cpu);
> +#else
> + return 0;
> +#endif
> +}
> +
> #endif /* CONFIG_NUMA && CONFIG_PPC_SPLPAR */
>
> #include <asm-generic/topology.h>
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index ef19eeccd21e..bb25c13bbb79 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -80,6 +80,7 @@ DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
> DEFINE_PER_CPU(cpumask_var_t, cpu_smallcore_map);
> DEFINE_PER_CPU(cpumask_var_t, cpu_l2_cache_map);
> DEFINE_PER_CPU(cpumask_var_t, cpu_core_map);
> +DEFINE_PER_CPU(cpumask_var_t, cpu_coregroup_map);
>
> EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
> EXPORT_PER_CPU_SYMBOL(cpu_l2_cache_map);
> @@ -91,6 +92,7 @@ enum {
> smt_idx,
> #endif
> bigcore_idx,
> + mc_idx,
> die_idx,
> };
>
> @@ -869,6 +871,21 @@ static const struct cpumask *smallcore_smt_mask(int cpu)
> }
> #endif
>
> +static struct cpumask *cpu_coregroup_mask(int cpu)
> +{
> + return per_cpu(cpu_coregroup_map, cpu);
> +}
> +
> +static bool has_coregroup_support(void)
> +{
> + return coregroup_enabled;
> +}
> +
> +static const struct cpumask *cpu_mc_mask(int cpu)
> +{
> + return cpu_coregroup_mask(cpu);
> +}
> +
> static const struct cpumask *cpu_bigcore_mask(int cpu)
> {
> return cpu_core_mask(cpu);
> @@ -879,6 +896,7 @@ static struct sched_domain_topology_level
> powerpc_topology[] = {
> { cpu_smt_mask, powerpc_smt_flags, SD_INIT_NAME(SMT) },
> #endif
> { cpu_bigcore_mask, SD_INIT_NAME(BIGCORE) },
> + { cpu_mc_mask, SD_INIT_NAME(MC) },
> { cpu_cpu_mask, SD_INIT_NAME(DIE) },
> { NULL, },
> };
> @@ -933,6 +951,10 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> GFP_KERNEL, node);
> zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu),
> GFP_KERNEL, node);
> + if (has_coregroup_support())
> + zalloc_cpumask_var_node(&per_cpu(cpu_coregroup_map,
> cpu),
> + GFP_KERNEL, node);
> +
> #ifdef CONFIG_NEED_MULTIPLE_NODES
> /*
> * numa_node_id() works after this.
> @@ -950,6 +972,11 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> cpumask_set_cpu(boot_cpuid, cpu_l2_cache_mask(boot_cpuid));
> cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));
>
> + if (has_coregroup_support())
> + cpumask_set_cpu(boot_cpuid, cpu_coregroup_mask(boot_cpuid));
> + else
> + powerpc_topology[mc_idx].mask = cpu_bigcore_mask;
> +
The else part could be moved to the common function where we are
modifying the other attributes of the topology array.
> init_big_cores();
> if (has_big_cores) {
> cpumask_set_cpu(boot_cpuid,
> @@ -1241,6 +1268,8 @@ static void remove_cpu_from_masks(int cpu)
> set_cpus_unrelated(cpu, i, cpu_sibling_mask);
> if (has_big_cores)
> set_cpus_unrelated(cpu, i, cpu_smallcore_mask);
> + if (has_coregroup_support())
> + set_cpus_unrelated(cpu, i, cpu_coregroup_mask);
> }
> }
> #endif
> @@ -1301,6 +1330,14 @@ static void add_cpu_to_masks(int cpu)
> add_cpu_to_smallcore_masks(cpu);
> update_mask_by_l2(cpu, cpu_l2_cache_mask);
>
> + if (has_coregroup_support()) {
> + cpumask_set_cpu(cpu, cpu_coregroup_mask(cpu));
> + for_each_cpu(i, cpu_online_mask) {
> + if (cpu_to_coregroup_id(cpu) == cpu_to_coregroup_id(i))
> + set_cpus_related(cpu, i, cpu_coregroup_mask);
> + }
> + }
> +
> if (pkg_id == -1) {
> struct cpumask *(*mask)(int) = cpu_sibling_mask;
>
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index a43eab455be4..d9ab9da85eab 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -1695,6 +1695,11 @@ static const struct proc_ops topology_proc_ops = {
> .proc_release = single_release,
> };
>
> +int cpu_to_coregroup_id(int cpu)
> +{
> + return cpu_to_core_id(cpu);
> +}
So, if has_coregroup_support() returns true, then since the core_group
identification is currently done through the core-id, the
coregroup_mask is going to be the same as the
cpu_core_mask/cpu_cpu_mask. Thus, we will be degenerating the DIE
domain. Right ? Instead we could have kept the core-group to be a
single bigcore by default, so that those domains can get degenerated
preserving the legacy SMT, DIE, NUMA hierarchy.
> +
> static int topology_update_init(void)
> {
> start_topology_update();
> --
> 2.17.1
>
