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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The documentation on cpu topology seems to be a bit out-of-date.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>
hifive-unleashed-5.1
Bartosz Golaszewski 2015-05-26 15:11:29 +02:00 committed by Ingo Molnar
parent 06931e6224
commit 54a5369487
1 changed files with 26 additions and 9 deletions

View File

@ -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().