[PATCH 4/6] Topology: Add cluster on die macros and arm64 decoding

[Xiongfeng Wang]

Hi Jeremy,

On 2017/9/15 2:49, Jeremy Linton wrote:
> Many modern machines have cluster on die (COD) non-uniformity
> as well as the traditional multi-socket architectures. Reusing
> the multi-socket or NUMA on die concepts for these (as arm64 does)
> breaks down when presented with actual multi-socket/COD machines.
> Similar, problems are also visible on some x86 machines so it
> seems appropriate to start abstracting and making these topologies
> visible.
> 
> To start, a topology_cod_id() macro is added which defaults to returning
> the same information as topology_physical_package_id(). Moving forward
> we can start to spit out the differences.
> 
> For arm64, an additional package_id is added to the cpu_topology array.
> Initially this will be equal to the cluster_id as well.
> 
> Signed-off-by: Jeremy Linton <jeremy.linton at arm.com>
> ---
>  arch/arm64/include/asm/topology.h | 4 +++-
>  arch/arm64/kernel/topology.c      | 8 ++++++--
>  include/linux/topology.h          | 3 +++
>  3 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
> index 8b57339823e9..bd7517960d39 100644
> --- a/arch/arm64/include/asm/topology.h
> +++ b/arch/arm64/include/asm/topology.h
> @@ -7,13 +7,15 @@ struct cpu_topology {
>  	int thread_id;
>  	int core_id;
>  	int cluster_id;
> +	int package_id;
>  	cpumask_t thread_sibling;
>  	cpumask_t core_sibling;
>  };

'core_sibling' will be updated by 'update_siblings_masks()' to represent cores in a cluster;
Can we add a cpumask_t field to represent cores in a package? So that 'lstopo' can use this
cpumask_t to display the right information.

Thanks,
Xiongfeng Wang

>  
>  extern struct cpu_topology cpu_topology[NR_CPUS];
>  
> -#define topology_physical_package_id(cpu)	(cpu_topology[cpu].cluster_id)
> +#define topology_physical_package_id(cpu)	(cpu_topology[cpu].package_id)
> +#define topology_cod_id(cpu)		(cpu_topology[cpu].cluster_id)
>  #define topology_core_id(cpu)		(cpu_topology[cpu].core_id)
>  #define topology_core_cpumask(cpu)	(&cpu_topology[cpu].core_sibling)
>  #define topology_sibling_cpumask(cpu)	(&cpu_topology[cpu].thread_sibling)
> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index 8d48b233e6ce..9147e5b6326d 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
> @@ -67,6 +67,8 @@ static int __init parse_core(struct device_node *core, int cluster_id,
>  			leaf = false;
>  			cpu = get_cpu_for_node(t);
>  			if (cpu >= 0) {
> +				/* maintain DT cluster == package behavior */
> +				cpu_topology[cpu].package_id = cluster_id;
>  				cpu_topology[cpu].cluster_id = cluster_id;
>  				cpu_topology[cpu].core_id = core_id;
>  				cpu_topology[cpu].thread_id = i;
> @@ -88,7 +90,7 @@ static int __init parse_core(struct device_node *core, int cluster_id,
>  			       core);
>  			return -EINVAL;
>  		}
> -
> +		cpu_topology[cpu].package_id = cluster_id;
>  		cpu_topology[cpu].cluster_id = cluster_id;
>  		cpu_topology[cpu].core_id = core_id;
>  	} else if (leaf) {
> @@ -228,7 +230,7 @@ static void update_siblings_masks(unsigned int cpuid)
>  	for_each_possible_cpu(cpu) {
>  		cpu_topo = &cpu_topology[cpu];
>  
> -		if (cpuid_topo->cluster_id != cpu_topo->cluster_id)
> +		if (cpuid_topo->package_id != cpu_topo->package_id)
>  			continue;
>  
>  		cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
> @@ -273,6 +275,7 @@ void store_cpu_topology(unsigned int cpuid)
>  					 MPIDR_AFFINITY_LEVEL(mpidr, 2) << 8 |
>  					 MPIDR_AFFINITY_LEVEL(mpidr, 3) << 16;
>  	}
> +	cpuid_topo->package_id = cpuid_topo->cluster_id;
>  
>  	pr_debug("CPU%u: cluster %d core %d thread %d mpidr %#016llx\n",
>  		 cpuid, cpuid_topo->cluster_id, cpuid_topo->core_id,
> @@ -292,6 +295,7 @@ static void __init reset_cpu_topology(void)
>  		cpu_topo->thread_id = -1;
>  		cpu_topo->core_id = 0;
>  		cpu_topo->cluster_id = -1;
> +		cpu_topo->package_id = -1;
>  
>  		cpumask_clear(&cpu_topo->core_sibling);
>  		cpumask_set_cpu(cpu, &cpu_topo->core_sibling);
> diff --git a/include/linux/topology.h b/include/linux/topology.h
> index cb0775e1ee4b..4660749a7303 100644
> --- a/include/linux/topology.h
> +++ b/include/linux/topology.h
> @@ -184,6 +184,9 @@ static inline int cpu_to_mem(int cpu)
>  #ifndef topology_physical_package_id
>  #define topology_physical_package_id(cpu)	((void)(cpu), -1)
>  #endif
> +#ifndef topology_cod_id				/* cluster on die */
> +#define topology_cod_id(cpu)			topology_physical_package_id(cpu)
> +#endif
>  #ifndef topology_core_id
>  #define topology_core_id(cpu)			((void)(cpu), 0)
>  #endif
>