[PATCH 8/8] topology: Update CPU topology documentation

Andreas Herrmann
2009-08-07T13:07:05Z

Mention new attributes introduced for multi-node processor support.

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
---
Documentation/cputopology.txt | 35 +++++++++++++++++++++++++++++------
1 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
index b41f3e5..48914b1 100644
--- a/Documentation/cputopology.txt
+++ b/Documentation/cputopology.txt
@@ -3,13 +3,32 @@ Export cpu topology info via sysfs. Items (attributes) are similar
to /proc/cpuinfo.

1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
-represent the physical package id of cpu X;
+ represents the physical package id of cpu X;
2) /sys/devices/system/cpu/cpuX/topology/core_id:
-represent the cpu core id to cpu X;
-3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
-represent the thread siblings to cpu X in the same core;
-4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
-represent the thread siblings to cpu X in the same physical package;
+ represents the cpu core id of cpu X;
+3) /sys/devices/system/cpu/cpuX/topology/cpu_node_id:
+ represents the processor internal node_id of cpu X;
+4) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
+ represents the thread siblings of cpu X in the same core;
+5) /sys/devices/system/cpu/cpuX/topology/core_siblings:
+ represents the thread siblings of cpu X in the same processor
+ internal node;
+6) /sys/devices/system/cpu/cpuX/topology/cpu_node_siblings:
+ represents the thread siblings of cpu X in the same physical
+ package;
+
+Note: cpu_node_siblings and core_siblings differ only on
+ multi-node processors. On all other processors they are
+ identical and then cpu_node_id is always 0.
+
+With that CPU topology is mapped into following hierarchy:
+
+ Level | Set of CPUs
+ --------------|---------------
+ phys_package | cpu_node_siblings
+ cpu_node | core_siblings
+ core | thread_siblings
+ thread | one CPU

To implement it in an architecture-neutral way, a new source file,
drivers/base/topology.c, is to export the 4 attributes.
@@ -20,6 +39,8 @@ these macros in include/asm-XXX/topology.h:
#define topology_core_id(cpu)
#define topology_thread_cpumask(cpu)
#define topology_core_cpumask(cpu)
+#define topology_cpu_node_id(cpu)
+#define topology_cpu_node_siblings(cpu)

The type of **_id is int.
The type of siblings is (const) struct cpumask *.
@@ -31,6 +52,8 @@ not defined by include/asm-XXX/topology.h:
2) core_id: 0
3) thread_siblings: just the given CPU
4) core_siblings: just the given CPU
+5) cpu_node_id: 0
+6) cpu_node_siblings: identical to core_siblings

Additionally, cpu topology information is provided under
/sys/devices/system/cpu and includes these files. The internal
--
1.6.3.3