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Message-ID: <20080418161121.GO21637@solarflare.com>
Date: Fri, 18 Apr 2008 17:11:22 +0100
From: Ben Hutchings <bhutchings@...arflare.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>
Subject: [PATCH][RFC] Add default CPU topology information (try #2)
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
include/asm-generic/topology_cpu.h.
- Changes include/asm-*/topology.h to include <asm-generic/topology_cpu.h>
unless all 4 macros are defined.
- Changes drivers/base/topology.c to use the topology macros unconditionally
and to cope with definitions that aren't lvalues.
- Updates documentation accordingly.
Unlike the previous version of this patch, it does not add inclusion of
<asm-generic/topology.h>.
Signed-off-by: Ben Hutchings <bhutchings@...arflare.com>
diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
index b61cb95..fb9bbe4 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:
+If one architecture wants 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 +24,11 @@ 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.
-
+Any architecture or configuration that does not define all these
+macros must include <asm-generic/topology_cpu.h> which provides
+default definitions for any of the above macros that are not
+already defined:
+1) physical_package_id: -1
+2) core_id: 0
+3) thread_siblings: just the given CPU
+4) core_siblings: just the given CPU
diff --git a/drivers/base/topology.c b/drivers/base/topology.c
index e1d3ad4..dfcb2e2 100644
--- a/drivers/base/topology.c
+++ b/drivers/base/topology.c
@@ -45,47 +45,28 @@ static ssize_t show_##name(struct sys_device *dev, char *buf) \
{ \
ssize_t len = -1; \
unsigned int cpu = dev->id; \
- len = cpumask_scnprintf(buf, NR_CPUS+1, topology_##name(cpu)); \
+ cpumask_t siblings = topology_##name(cpu); \
+ len = cpumask_scnprintf(buf, NR_CPUS+1, siblings); \
return (len + sprintf(buf + len, "\n")); \
}
-#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 ref_thread_siblings_attr &attr_thread_siblings.attr,
-#else
-#define ref_thread_siblings_attr
-#endif
-#ifdef topology_core_siblings
define_siblings_show_func(core_siblings);
define_one_ro(core_siblings);
-#define ref_core_siblings_attr &attr_core_siblings.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_core_siblings.attr,
NULL
};
diff --git a/include/asm-alpha/topology.h b/include/asm-alpha/topology.h
index 420ccde..57ef8b1 100644
--- a/include/asm-alpha/topology.h
+++ b/include/asm-alpha/topology.h
@@ -41,6 +41,8 @@ static inline cpumask_t node_to_cpumask(int node)
#define pcibus_to_cpumask(bus) (cpu_online_map)
+#include <asm-generic/topology_cpu.h>
+
#else /* CONFIG_NUMA */
# include <asm-generic/topology.h>
#endif /* !CONFIG_NUMA */
diff --git a/include/asm-generic/topology.h b/include/asm-generic/topology.h
index 342a2a0..f784625 100644
--- a/include/asm-generic/topology.h
+++ b/include/asm-generic/topology.h
@@ -52,4 +52,6 @@
)
#endif
+#include <asm-generic/topology_cpu.h>
+
#endif /* _ASM_GENERIC_TOPOLOGY_H */
diff --git a/include/asm-generic/topology_cpu.h b/include/asm-generic/topology_cpu.h
new file mode 100644
index 0000000..fac1258
--- /dev/null
+++ b/include/asm-generic/topology_cpu.h
@@ -0,0 +1,19 @@
+#ifndef _ASM_GENERIC_TOPOLOGY_CPU_H
+#define _ASM_GENERIC_TOPOLOGY_CPU_H
+
+#include <linux/cpumask.h>
+
+#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 /* _ASM_GENERIC_TOPOLOGY_CPU_H */
diff --git a/include/asm-powerpc/topology.h b/include/asm-powerpc/topology.h
index ca23b68..abcfdf4 100644
--- a/include/asm-powerpc/topology.h
+++ b/include/asm-powerpc/topology.h
@@ -97,8 +97,6 @@ static inline void sysfs_remove_device_from_node(struct sys_device *dev,
}
-#include <asm-generic/topology.h>
-
#endif /* CONFIG_NUMA */
#ifdef CONFIG_SMP
@@ -112,5 +110,11 @@ static inline void sysfs_remove_device_from_node(struct sys_device *dev,
#endif
#endif
+#ifdef CONFIG_NUMA
+#include <asm-generic/topology_cpu.h>
+#else
+#include <asm-generic/topology.h>
+#endif
+
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_TOPOLOGY_H */
diff --git a/include/asm-x86/topology.h b/include/asm-x86/topology.h
index 8af05a9..49b1a73 100644
--- a/include/asm-x86/topology.h
+++ b/include/asm-x86/topology.h
@@ -178,6 +178,8 @@ extern cpumask_t cpu_coregroup_map(int cpu);
#define topology_core_id(cpu) (cpu_data(cpu).cpu_core_id)
#define topology_core_siblings(cpu) (per_cpu(cpu_core_map, cpu))
#define topology_thread_siblings(cpu) (per_cpu(cpu_sibling_map, cpu))
+#else
+#include <asm-generic/topology_cpu.h>
#endif
#ifdef CONFIG_SMP
--
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
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