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authorIngo Molnar <mingo@elte.hu>2008-07-18 19:53:16 +0200
committerIngo Molnar <mingo@elte.hu>2008-07-18 19:53:16 +0200
commit9b610fda0df5d0f0b0c64242e37441ad1b384aac (patch)
tree0ea14b15f2e6546f37fe18d8ac3dc83077ec0e55 /Documentation/cputopology.txt
parentb8f8c3cf0a4ac0632ec3f0e15e9dc0c29de917af (diff)
parent5b664cb235e97afbf34db9c4d77f08ebd725335e (diff)
downloadtalos-op-linux-9b610fda0df5d0f0b0c64242e37441ad1b384aac.tar.gz
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Merge branch 'linus' into timers/nohz
Diffstat (limited to 'Documentation/cputopology.txt')
-rw-r--r--Documentation/cputopology.txt26
1 files changed, 9 insertions, 17 deletions
diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
index b61cb9564023..bd699da24666 100644
--- a/Documentation/cputopology.txt
+++ b/Documentation/cputopology.txt
@@ -14,9 +14,8 @@ represent the thread siblings to cpu X in the same physical package;
To implement it in an architecture-neutral way, a new source file,
drivers/base/topology.c, is to export the 4 attributes.
-If one architecture wants to support this feature, it just needs to
-implement 4 defines, typically in file include/asm-XXX/topology.h.
-The 4 defines are:
+For an architecture to support this feature, it must define some of
+these macros in include/asm-XXX/topology.h:
#define topology_physical_package_id(cpu)
#define topology_core_id(cpu)
#define topology_thread_siblings(cpu)
@@ -25,17 +24,10 @@ The 4 defines are:
The type of **_id is int.
The type of siblings is cpumask_t.
-To be consistent on all architectures, the 4 attributes should have
-default values if their values are unavailable. Below is the rule.
-1) physical_package_id: If cpu has no physical package id, -1 is the
-default value.
-2) core_id: If cpu doesn't support multi-core, its core id is 0.
-3) thread_siblings: Just include itself, if the cpu doesn't support
-HT/multi-thread.
-4) core_siblings: Just include itself, if the cpu doesn't support
-multi-core and HT/Multi-thread.
-
-So be careful when declaring the 4 defines in include/asm-XXX/topology.h.
-
-If an attribute isn't defined on an architecture, it won't be exported.
-
+To be consistent on all architectures, include/linux/topology.h
+provides default definitions for any of the above macros that are
+not defined by include/asm-XXX/topology.h:
+1) physical_package_id: -1
+2) core_id: 0
+3) thread_siblings: just the given CPU
+4) core_siblings: just the given CPU
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