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

[Jeremy Linton]

Hi,


On 09/17/2017 08:50 PM, Xiongfeng Wang wrote:
> 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.

So, the change below modifies update_siblings_mask() to utilize the 
package_id. Per the ABI the ..cpuX/topology/physical_package_id is 
shared between the core_siblings/core_siblings_list. What 
physical_package_id means can vary per architecture, but the siblings 
list needs to be the cores with the same phyiscal_package (AFAIK, feel 
free to correct my understanding). That rule should be enforced by this 
patch set.

I suspect if your running these patches, and the lstopo output looks 
strange its because your on a machine where the thread_id has been 
assigned the cluster_id in the later patch set.


> 
> 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)

(note here that core_siblings now reflect the package_id rather than the 
cluster_id. This only matters if cluster_id!=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
>>
> 
> 
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