The patch titled
cpu topology: always define CPU topology information
has been added to the -mm tree. Its filename is
cputopology-always-define-cpu-topology-information.patch
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------------------------------------------------------
Subject: cpu topology: always define CPU topology information
From: Ben Hutchings <bhutchings@xxxxxxxxxxxxxx>
Not all architectures and configurations define CPU topology information.
This can result in an empty topology directory in sysfs, and requires
in-kernel users to protect all uses with #ifdef - see
<http://marc.info/?l=linux-netdev&m=120639033904472&w=2>.
The documentation of CPU topology specifies what the defaults should be if
only partial information is available from the hardware. So we can
provide these defaults as a fallback.
This patch:
- Adds default definitions of the 4 topology macros to <linux/topology.h>
- Changes drivers/base/topology.c to use the topology macros unconditionally
and to cope with definitions that aren't lvalues
- Updates documentation accordingly
Signed-off-by: Ben Hutchings <bhutchings@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Cc: Chandra Seetharaman <sekharan@xxxxxxxxxx>
Cc: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
Cc: Mike Travis <travis@xxxxxxx>
Cc: Christoph Lameter <clameter@xxxxxxx>
Cc: John Hawkes <hawkes@xxxxxxx>
Cc: Zhang, Yanmin <yanmin.zhang@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/cputopology.txt | 26 +++++++--------------
drivers/base/topology.c | 38 ++++++++------------------------
include/linux/topology.h | 13 ++++++++++
3 files changed, 32 insertions(+), 45 deletions(-)
diff -puN Documentation/cputopology.txt~cputopology-always-define-cpu-topology-information Documentation/cputopology.txt
--- a/Documentation/cputopology.txt~cputopology-always-define-cpu-topology-information
+++ a/Documentation/cputopology.txt
@@ -14,9 +14,8 @@ represent the thread siblings to cpu X i
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
diff -puN drivers/base/topology.c~cputopology-always-define-cpu-topology-information drivers/base/topology.c
--- a/drivers/base/topology.c~cputopology-always-define-cpu-topology-information
+++ a/drivers/base/topology.c
@@ -62,14 +62,16 @@ static ssize_t show_cpumap(int type, cpu
static ssize_t show_##name(struct sys_device *dev, char *buf) \
{ \
unsigned int cpu = dev->id; \
- return show_cpumap(0, &(topology_##name(cpu)), buf); \
+ cpumask_t siblings = topology_##name(cpu); \
+ return show_cpumap(0, &siblings, buf); \
}
#define define_siblings_show_list(name) \
static ssize_t show_##name##_list(struct sys_device *dev, char *buf) \
{ \
unsigned int cpu = dev->id; \
- return show_cpumap(1, &(topology_##name(cpu)), buf); \
+ cpumask_t siblings = topology_##name(cpu); \
+ return show_cpumap(1, &siblings, buf); \
}
#else
@@ -93,47 +95,27 @@ static ssize_t show_##name##_list(struct
#define define_siblings_show_func(name) \
define_siblings_show_map(name); define_siblings_show_list(name)
-#ifdef topology_physical_package_id
define_id_show_func(physical_package_id);
define_one_ro(physical_package_id);
-#define ref_physical_package_id_attr &attr_physical_package_id.attr,
-#else
-#define ref_physical_package_id_attr
-#endif
-#ifdef topology_core_id
define_id_show_func(core_id);
define_one_ro(core_id);
-#define ref_core_id_attr &attr_core_id.attr,
-#else
-#define ref_core_id_attr
-#endif
-#ifdef topology_thread_siblings
define_siblings_show_func(thread_siblings);
define_one_ro(thread_siblings);
define_one_ro(thread_siblings_list);
-#define ref_thread_siblings_attr \
- &attr_thread_siblings.attr, &attr_thread_siblings_list.attr,
-#else
-#define ref_thread_siblings_attr
-#endif
-#ifdef topology_core_siblings
define_siblings_show_func(core_siblings);
define_one_ro(core_siblings);
define_one_ro(core_siblings_list);
-#define ref_core_siblings_attr \
- &attr_core_siblings.attr, &attr_core_siblings_list.attr,
-#else
-#define ref_core_siblings_attr
-#endif
static struct attribute *default_attrs[] = {
- ref_physical_package_id_attr
- ref_core_id_attr
- ref_thread_siblings_attr
- ref_core_siblings_attr
+ &attr_physical_package_id.attr,
+ &attr_core_id.attr,
+ &attr_thread_siblings.attr,
+ &attr_thread_siblings_list.attr,
+ &attr_core_siblings.attr,
+ &attr_core_siblings_list.attr,
NULL
};
diff -puN include/linux/topology.h~cputopology-always-define-cpu-topology-information include/linux/topology.h
--- a/include/linux/topology.h~cputopology-always-define-cpu-topology-information
+++ a/include/linux/topology.h
@@ -179,4 +179,17 @@ void arch_update_cpu_topology(void);
#endif
#endif /* CONFIG_NUMA */
+#ifndef topology_physical_package_id
+#define topology_physical_package_id(cpu) ((void)(cpu), -1)
+#endif
+#ifndef topology_core_id
+#define topology_core_id(cpu) ((void)(cpu), 0)
+#endif
+#ifndef topology_thread_siblings
+#define topology_thread_siblings(cpu) cpumask_of_cpu(cpu)
+#endif
+#ifndef topology_core_siblings
+#define topology_core_siblings(cpu) cpumask_of_cpu(cpu)
+#endif
+
#endif /* _LINUX_TOPOLOGY_H */
_
Patches currently in -mm which might be from bhutchings@xxxxxxxxxxxxxx are
cputopology-always-define-cpu-topology-information.patch
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