diff mbox

[RFC,2/2] ARM64: introduce cluster id and make a difference between socket id

Message ID 1374921728-9007-2-git-send-email-hanjun.guo@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Hanjun Guo July 27, 2013, 10:42 a.m. UTC
In the cpu topology information, we define topology_physical_package_id()
as cpu socket id, which means that the socket id is the idenfication for
physical processor, not for a cluster in a cpu die.

On ARM64 platform, multi cluster in a cpu die will be normal, here is a
example with 2 cores in a cluster and 2 cluster in a socket:

|--------------------------------------|
|                socket                |
|                                      |
| |---------------|  |---------------| |
| |    cluster    |  |    cluster    | |
| |               |  |               | |
| | |----| |----| |  | |----| |----| | |
| | |core| |core| |  | |core| |core| | |
| | |----| |----| |  | |----| |----| | |
| |               |  |               | |
| |---------------|  |---------------| |
|                                      |
|--------------------------------------|

ARM64 extended the MPIDR into 64 bit and introduce another affinity level,
we can use this affinity level for socket id and use the third highest level
affinity for cluster id, which  make the socket id behavior in its original
way.

Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
---
 arch/arm64/include/asm/topology.h |    1 +
 arch/arm64/kernel/topology.c      |    8 ++++++--
 2 files changed, 7 insertions(+), 2 deletions(-)

Comments

Vincent Guittot July 29, 2013, 9:38 a.m. UTC | #1
On 27 July 2013 12:42, Hanjun Guo <hanjun.guo@linaro.org> wrote:
> In the cpu topology information, we define topology_physical_package_id()
> as cpu socket id, which means that the socket id is the idenfication for
> physical processor, not for a cluster in a cpu die.
>
> On ARM64 platform, multi cluster in a cpu die will be normal, here is a
> example with 2 cores in a cluster and 2 cluster in a socket:
>
> |--------------------------------------|
> |                socket                |
> |                                      |
> | |---------------|  |---------------| |
> | |    cluster    |  |    cluster    | |
> | |               |  |               | |
> | | |----| |----| |  | |----| |----| | |
> | | |core| |core| |  | |core| |core| | |
> | | |----| |----| |  | |----| |----| | |
> | |               |  |               | |
> | |---------------|  |---------------| |
> |                                      |
> |--------------------------------------|
>
> ARM64 extended the MPIDR into 64 bit and introduce another affinity level,
> we can use this affinity level for socket id and use the third highest level
> affinity for cluster id, which  make the socket id behavior in its original
> way.
>
> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> ---
>  arch/arm64/include/asm/topology.h |    1 +
>  arch/arm64/kernel/topology.c      |    8 ++++++--
>  2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
> index 8631808..ff68ecc 100644
> --- a/arch/arm64/include/asm/topology.h
> +++ b/arch/arm64/include/asm/topology.h
> @@ -8,6 +8,7 @@
>  struct cputopo_arm64 {
>         int thread_id;
>         int core_id;
> +       int cluster_id;
>         int socket_id;
>         cpumask_t thread_sibling;
>         cpumask_t core_sibling;
> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index 1eb0435..6d1e5a6 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
> @@ -80,12 +80,14 @@ void store_cpu_topology(unsigned int cpuid)
>                         /* core performance interdependency */
>                         cpuid_topo->thread_id = MPIDR_AFFINITY_LEVEL_0(mpidr);
>                         cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL_1(mpidr);
> -                       cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL_2(mpidr);
> +                       cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL_2(mpidr);
> +                       cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL_3(mpidr);

socket_id is currently used by update_siblings_masks to update the
core_sibling mask. This mask defines which CPUs share their cache and
AFAICT, the cache are shared at the cluster level so cluster_id should
be used instead socket_id.

Have you got more information about the goal of this new level_3 ?

Vincent

>                 } else {
>                         /* largely independent cores */
>                         cpuid_topo->thread_id = -1;
>                         cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL_0(mpidr);
> -                       cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL_1(mpidr);
> +                       cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL_1(mpidr);
> +                       cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL_2(mpidr);
>                 }
>         } else {
>                 /*
> @@ -95,6 +97,7 @@ void store_cpu_topology(unsigned int cpuid)
>                  */
>                 cpuid_topo->thread_id = -1;
>                 cpuid_topo->core_id = 0;
> +               cpuid_topo->cluster_id = -1;
>                 cpuid_topo->socket_id = -1;
>         }
>
> @@ -120,6 +123,7 @@ void __init init_cpu_topology(void)
>
>                 topo->thread_id = -1;
>                 topo->core_id =  -1;
> +               topo->cluster_id = -1;
>                 topo->socket_id = -1;
>                 cpumask_clear(&topo->core_sibling);
>                 cpumask_clear(&topo->thread_sibling);
> --
> 1.7.9.5
>
Hanjun Guo July 30, 2013, 7:46 a.m. UTC | #2
On 2013-7-29 17:38, Vincent Guittot wrote:
> On 27 July 2013 12:42, Hanjun Guo <hanjun.guo@linaro.org> wrote:
>> In the cpu topology information, we define topology_physical_package_id()
>> as cpu socket id, which means that the socket id is the idenfication for
>> physical processor, not for a cluster in a cpu die.
>>
>> On ARM64 platform, multi cluster in a cpu die will be normal, here is a
>> example with 2 cores in a cluster and 2 cluster in a socket:
>>
>> |--------------------------------------|
>> |                socket                |
>> |                                      |
>> | |---------------|  |---------------| |
>> | |    cluster    |  |    cluster    | |
>> | |               |  |               | |
>> | | |----| |----| |  | |----| |----| | |
>> | | |core| |core| |  | |core| |core| | |
>> | | |----| |----| |  | |----| |----| | |
>> | |               |  |               | |
>> | |---------------|  |---------------| |
>> |                                      |
>> |--------------------------------------|
>>
>> ARM64 extended the MPIDR into 64 bit and introduce another affinity level,
>> we can use this affinity level for socket id and use the third highest level
>> affinity for cluster id, which  make the socket id behavior in its original
>> way.
>>
>> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
>> ---
>>  arch/arm64/include/asm/topology.h |    1 +
>>  arch/arm64/kernel/topology.c      |    8 ++++++--
>>  2 files changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
>> index 8631808..ff68ecc 100644
>> --- a/arch/arm64/include/asm/topology.h
>> +++ b/arch/arm64/include/asm/topology.h
>> @@ -8,6 +8,7 @@
>>  struct cputopo_arm64 {
>>         int thread_id;
>>         int core_id;
>> +       int cluster_id;
>>         int socket_id;
>>         cpumask_t thread_sibling;
>>         cpumask_t core_sibling;
>> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
>> index 1eb0435..6d1e5a6 100644
>> --- a/arch/arm64/kernel/topology.c
>> +++ b/arch/arm64/kernel/topology.c
>> @@ -80,12 +80,14 @@ void store_cpu_topology(unsigned int cpuid)
>>                         /* core performance interdependency */
>>                         cpuid_topo->thread_id = MPIDR_AFFINITY_LEVEL_0(mpidr);
>>                         cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL_1(mpidr);
>> -                       cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL_2(mpidr);
>> +                       cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL_2(mpidr);
>> +                       cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL_3(mpidr);
> 
> socket_id is currently used by update_siblings_masks to update the
> core_sibling mask. This mask defines which CPUs share their cache and
> AFAICT, the cache are shared at the cluster level so cluster_id should
> be used instead socket_id.

For some architecture, cpu cores in a cluster share L2 cache, and clusters
in the cpu die share L3 cache, so I think we can make a difference between
socket id and cluster id.

> 
> Have you got more information about the goal of this new level_3 ?

Actually not, I think ARM should give some recommendations as ARMv7 did.

Thanks
Hanjun
diff mbox

Patch

diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
index 8631808..ff68ecc 100644
--- a/arch/arm64/include/asm/topology.h
+++ b/arch/arm64/include/asm/topology.h
@@ -8,6 +8,7 @@ 
 struct cputopo_arm64 {
 	int thread_id;
 	int core_id;
+	int cluster_id;
 	int socket_id;
 	cpumask_t thread_sibling;
 	cpumask_t core_sibling;
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 1eb0435..6d1e5a6 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -80,12 +80,14 @@  void store_cpu_topology(unsigned int cpuid)
 			/* core performance interdependency */
 			cpuid_topo->thread_id = MPIDR_AFFINITY_LEVEL_0(mpidr);
 			cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL_1(mpidr);
-			cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL_2(mpidr);
+			cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL_2(mpidr);
+			cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL_3(mpidr);
 		} else {
 			/* largely independent cores */
 			cpuid_topo->thread_id = -1;
 			cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL_0(mpidr);
-			cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL_1(mpidr);
+			cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL_1(mpidr);
+			cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL_2(mpidr);
 		}
 	} else {
 		/*
@@ -95,6 +97,7 @@  void store_cpu_topology(unsigned int cpuid)
 		 */
 		cpuid_topo->thread_id = -1;
 		cpuid_topo->core_id = 0;
+		cpuid_topo->cluster_id = -1;
 		cpuid_topo->socket_id = -1;
 	}
 
@@ -120,6 +123,7 @@  void __init init_cpu_topology(void)
 
 		topo->thread_id = -1;
 		topo->core_id =  -1;
+		topo->cluster_id = -1;
 		topo->socket_id = -1;
 		cpumask_clear(&topo->core_sibling);
 		cpumask_clear(&topo->thread_sibling);