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authorBartosz Golaszewski <bgolaszewski@baylibre.com>2015-05-26 15:11:29 +0200
committerIngo Molnar <mingo@kernel.org>2015-05-27 15:22:15 +0200
commit54a5369487fc0a9506bbf31ab2e00e5dc5d6d4cd (patch)
treeac6d376cfb4f9dd308c21252c4e894c80e38b05f
parent06931e62246844c73fba24d7aeb4a5dc897a2739 (diff)
Documentation: Update cputopology.txt
The documentation on cpu topology seems to be a bit out-of-date. It doesn't mention the **_siblings_list attributes and uses old names for topology_**_cpumask() macros. Add information on missing attributes plus some additional clarifications. Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> Cc: Benoit Cousson <bcousson@baylibre.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Jean Delvare <jdelvare@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Drokin <oleg.drokin@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Cc: Russell King <linux@arm.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Link: http://lkml.kernel.org/r/1432645896-12588-3-git-send-email-bgolaszewski@baylibre.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--Documentation/cputopology.txt35
1 files changed, 26 insertions, 9 deletions
diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
index 428a961ff063..12b1b25b4da9 100644
--- a/Documentation/cputopology.txt
+++ b/Documentation/cputopology.txt
@@ -1,6 +1,6 @@
Export CPU topology info via sysfs. Items (attributes) are similar
-to /proc/cpuinfo.
+to /proc/cpuinfo output of some architectures:
1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
@@ -23,20 +23,35 @@ to /proc/cpuinfo.
4) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
internal kernel map of cpuX's hardware threads within the same
- core as cpuX
+ core as cpuX.
-5) /sys/devices/system/cpu/cpuX/topology/core_siblings:
+5) /sys/devices/system/cpu/cpuX/topology/thread_siblings_list:
+
+ human-readable list of cpuX's hardware threads within the same
+ core as cpuX.
+
+6) /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:
+7) /sys/devices/system/cpu/cpuX/topology/core_siblings_list:
+
+ human-readable list of cpuX's hardware threads within the same
+ physical_package_id.
+
+8) /sys/devices/system/cpu/cpuX/topology/book_siblings:
internal kernel map of cpuX's hardware threads within the same
book_id.
+9) /sys/devices/system/cpu/cpuX/topology/book_siblings_list:
+
+ human-readable list 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 or 6 attributes. The two book
+drivers/base/topology.c, is to export the 6 or 9 attributes. The three 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
@@ -48,16 +63,18 @@ these macros in include/asm-XXX/topology.h:
#define topology_core_cpumask(cpu)
#define topology_book_cpumask(cpu)
-The type of **_id is int.
-The type of siblings is (const) struct cpumask *.
+The type of **_id macros is int.
+The type of **_cpumask macros is (const) struct cpumask *. The latter
+correspond with appropriate **_siblings sysfs attributes (except for
+topology_sibling_cpumask() which corresponds with thread_siblings).
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
+3) sibling_cpumask: just the given CPU
+4) core_cpumask: 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().