Subject: Re: [PATCH v4 09/10] Powerpc/smp: Create coregroup domain

From: Gautham R Shenoy <[email-masked]>
Date: Tue, 28 Jul 2020 00:22:49 +0530

Hi Srikar,

On Mon, Jul 27, 2020 at 11:02:29AM +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 <[email-masked]>
> Cc: LKML <[email-masked]>
> Cc: Michael Ellerman <[email-masked]>
> Cc: Nicholas Piggin <[email-masked]>
> Cc: Anton Blanchard <[email-masked]>
> Cc: Oliver O'Halloran <[email-masked]>
> Cc: Nathan Lynch <[email-masked]>
> Cc: Michael Neuling <[email-masked]>
> Cc: Gautham R Shenoy <[email-masked]>
> Cc: Ingo Molnar <[email-masked]>
> Cc: Peter Zijlstra <[email-masked]>
> Cc: Valentin Schneider <[email-masked]>
> Cc: Jordan Niethe <[email-masked]>
> Signed-off-by: Srikar Dronamraju <[email-masked]>

This version looks good to me.

Reviewed-by: Gautham R. Shenoy <[email-masked]>

> ---
> Changelog v3 ->v4:
> 	if coregroup_support doesn't exist, update MC mask to the next
> 	smaller domain mask.
> 
> Changelog v2 -> v3:
> 	Add optimization for mask updation under coregroup_support
> 
> Changelog v1 -> v2:
> 	Moved coregroup topology fixup to fixup_topology (Gautham)
> 
>  arch/powerpc/include/asm/topology.h | 10 +++++++
>  arch/powerpc/kernel/smp.c           | 44 +++++++++++++++++++++++++++++
>  arch/powerpc/mm/numa.c              |  5 ++++
>  3 files changed, 59 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
> index f0b6300e7dd3..6609174918ab 100644
> --- a/arch/powerpc/include/asm/topology.h
> +++ b/arch/powerpc/include/asm/topology.h
> @@ -88,12 +88,22 @@ static inline int cpu_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)
> 
>  #if defined(CONFIG_NUMA) && defined(CONFIG_PPC_SPLPAR)
>  extern int find_and_online_cpu_nid(int cpu);
> +extern int cpu_to_coregroup_id(int cpu);
>  #else
>  static inline int find_and_online_cpu_nid(int cpu)
>  {
>  	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 dab96a1203ec..95f0bf72e283 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 per_cpu(cpu_sibling_map, 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, },
>  };
> @@ -925,6 +943,10 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
>  					GFP_KERNEL, cpu_to_node(cpu));
>  		zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu),
>  					GFP_KERNEL, cpu_to_node(cpu));
> +		if (has_coregroup_support())
> +			zalloc_cpumask_var_node(&per_cpu(cpu_coregroup_map, cpu),
> +						GFP_KERNEL, cpu_to_node(cpu));
> +
>  #ifdef CONFIG_NEED_MULTIPLE_NODES
>  		/*
>  		 * numa_node_id() works after this.
> @@ -942,6 +964,9 @@ 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));
> +
>  	init_big_cores();
>  	if (has_big_cores) {
>  		cpumask_set_cpu(boot_cpuid,
> @@ -1233,6 +1258,8 @@ 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
> @@ -1293,6 +1320,20 @@ 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()) {
> +		int coregroup_id = cpu_to_coregroup_id(cpu);
> +
> +		cpumask_set_cpu(cpu, cpu_coregroup_mask(cpu));
> +		for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
> +			int fcpu = cpu_first_thread_sibling(i);
> +
> +			if (fcpu == first_thread)
> +				set_cpus_related(cpu, i, cpu_coregroup_mask);
> +			else if (coregroup_id == cpu_to_coregroup_id(i))
> +				set_cpus_related(cpu, i, cpu_coregroup_mask);
> +		}
> +	}
> +
>  	if (pkg_id == -1) {
>  		struct cpumask *(*mask)(int) = cpu_sibling_mask;
> 
> @@ -1398,6 +1439,9 @@ static void fixup_topology(void)
>  		powerpc_topology[bigcore_idx].name = "CACHE";
>  #endif
>  	}
> +
> +	if (!has_coregroup_support())
> +		powerpc_topology[mc_idx].mask = powerpc_topology[bigcore_idx].mask;
>  }
> 
>  void __init smp_cpus_done(unsigned int max_cpus)
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index 51cb672f113b..0d57779e7942 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -1216,6 +1216,11 @@ int find_and_online_cpu_nid(int cpu)
>  	return new_nid;
>  }
> 
> +int cpu_to_coregroup_id(int cpu)
> +{
> +	return cpu_to_core_id(cpu);
> +}
> +
>  static int topology_update_init(void)
>  {
>  	topology_inited = 1;
> -- 
> 2.17.1
>