[PATCH/RFC 4/5] [PATCH] topology/sysfs: provide book id and siblings attributes

Heiko Carstens
2010-08-12T17:24:52Z

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From: Heiko Carstens <heiko.carstens@de.ibm.com>

Create attributes
/sys/devices/system/cpu/cpuX/topology/book_id
/sys/devices/system/cpu/cpuX/topology/book_siblings
which show the book id and the book siblings of a cpu.

Unlike the attributes for SMT and MC these attributes are only present if
CONFIG_SCHED_BOOK is set. There is no reason to pollute sysfs for every
architecture with unused attributes.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
---

Documentation/cputopology.txt | 23 ++++++++++++++++++++---
drivers/base/topology.c | 16 +++++++++++++++-
2 files changed, 35 insertions(+), 4 deletions(-)

diff -urpN linux-2.6/Documentation/cputopology.txt linux-2.6-patched/Documentation/cputopology.txt
--- linux-2.6/Documentation/cputopology.txt 2010-08-02 00:11:14.000000000 +0200
+++ linux-2.6-patched/Documentation/cputopology.txt 2010-08-11 13:47:23.000000000 +0200
@@ -14,25 +14,39 @@ to /proc/cpuinfo.
identifier (rather than the kernel's). The actual value is
architecture and platform dependent.

-3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
+3) /sys/devices/system/cpu/cpuX/topology/book_id:
+
+ the book ID of cpuX. Typically it is the hardware platform's
+ identifier (rather than the kernel's). The actual value is
+ architecture and platform dependent.
+
+4) /sys/devices/system/cpu/cpuX/topology/thread_siblings:

internel kernel map of cpuX's hardware threads within the same
core as cpuX

-4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
+5) /sys/devices/system/cpu/cpuX/topology/core_siblings:

internal kernel map of cpuX's hardware threads within the same
physical_package_id.

+6) /sys/devices/system/cpu/cpuX/topology/book_siblings:
+
+ internal kernel map of cpuX's hardware threads within the same
+ book_id.
+
To implement it in an architecture-neutral way, a new source file,
-drivers/base/topology.c, is to export the 4 attributes.
+drivers/base/topology.c, is to export the 4 or 6 attributes. The two book
+related sysfs files will only be created if CONFIG_SCHED_BOOK is selected.

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_book_id(cpu)
#define topology_thread_cpumask(cpu)
#define topology_core_cpumask(cpu)
+#define topology_book_cpumask(cpu)

The type of **_id is int.
The type of siblings is (const) struct cpumask *.
@@ -45,6 +59,9 @@ not defined by include/asm-XXX/topology.
3) thread_siblings: just the given CPU
4) core_siblings: just the given CPU

+For architectures that don't support books (CONFIG_SCHED_BOOK) there are no
+default definitions for topology_book_id() and topology_book_cpumask().
+
Additionally, CPU topology information is provided under
/sys/devices/system/cpu and includes these files. The internal
source for the output is in brackets ("[]").
diff -urpN linux-2.6/drivers/base/topology.c linux-2.6-patched/drivers/base/topology.c
--- linux-2.6/drivers/base/topology.c 2010-08-02 00:11:14.000000000 +0200
+++ linux-2.6-patched/drivers/base/topology.c 2010-08-11 13:47:23.000000000 +0200
@@ -45,7 +45,8 @@ static ssize_t show_##name(struct sys_de
return sprintf(buf, "%d\n", topology_##name(cpu)); \
}

-#if defined(topology_thread_cpumask) || defined(topology_core_cpumask)
+#if defined(topology_thread_cpumask) || defined(topology_core_cpumask) || \
+ defined(topology_book_cpumask)
static ssize_t show_cpumap(int type, const struct cpumask *mask, char *buf)
{
ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf;
@@ -114,6 +115,14 @@ define_siblings_show_func(core_cpumask);
define_one_ro_named(core_siblings, show_core_cpumask);
define_one_ro_named(core_siblings_list, show_core_cpumask_list);

+#ifdef CONFIG_SCHED_BOOK
+define_id_show_func(book_id);
+define_one_ro(book_id);
+define_siblings_show_func(book_cpumask);
+define_one_ro_named(book_siblings, show_book_cpumask);
+define_one_ro_named(book_siblings_list, show_book_cpumask_list);
+#endif
+
static struct attribute *default_attrs[] = {
&attr_physical_package_id.attr,
&attr_core_id.attr,
@@ -121,6 +130,11 @@ static struct attribute *default_attrs[]
&attr_thread_siblings_list.attr,
&attr_core_siblings.attr,
&attr_core_siblings_list.attr,
+#ifdef CONFIG_SCHED_BOOK
+ &attr_book_id.attr,
+ &attr_book_siblings.attr,
+ &attr_book_siblings_list.attr,
+#endif
NULL
};