From dc87e4b88551f64cb4053d8ea72dffc0c3675413 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Charles-Fran=C3=A7ois=20Natali?= <cf.natali@gmail.com>
Date: Mon, 13 Jul 2015 21:01:39 +0100
Subject: [PATCH] Issue #23530: Improve os.cpu_count() description. Patch by
 Julian Taylor.

---
 Doc/library/multiprocessing.rst | 9 +++++++--
 Doc/library/os.rst              | 5 +++++
 Misc/ACKS                       | 1 +
 Modules/posixmodule.c           | 6 ++++--
 4 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/Doc/library/multiprocessing.rst b/Doc/library/multiprocessing.rst
index 8703f8f5eca..e74430df7e1 100644
--- a/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@ -869,8 +869,13 @@ Miscellaneous
 
 .. function:: cpu_count()
 
-   Return the number of CPUs in the system.  May raise
-   :exc:`NotImplementedError`.
+   Return the number of CPUs in the system.
+
+   This number is not equivalent to the number of CPUs the current process can
+   use.  The number of usable CPUs can be obtained with
+   ``len(os.sched_getaffinity(0))``
+
+   May raise :exc:`NotImplementedError`.
 
    .. seealso::
       :func:`os.cpu_count`
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 16e5019f862..0acb8a570f7 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -3596,6 +3596,11 @@ Miscellaneous System Information
 
    Return the number of CPUs in the system. Returns None if undetermined.
 
+   This number is not equivalent to the number of CPUs the current process can
+   use.  The number of usable CPUs can be obtained with
+   ``len(os.sched_getaffinity(0))``
+
+
    .. versionadded:: 3.4
 
 
diff --git a/Misc/ACKS b/Misc/ACKS
index 8a007ea9dcb..e4ba783953f 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1385,6 +1385,7 @@ William Tanksley
 Christian Tanzer
 Steven Taschuk
 Amy Taylor
+Julian Taylor
 Monty Taylor
 Anatoly Techtonik
 Gustavo Temple
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index ec8c526c0aa..23d74a3e0e2 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -5760,7 +5760,7 @@ os.sched_getaffinity
     pid: pid_t
     /
 
-Return the affinity of the process identified by pid.
+Return the affinity of the process identified by pid (or the current process if zero).
 
 The affinity is returned as a set of CPU identifiers.
 [clinic start generated code]*/
@@ -11201,7 +11201,9 @@ get_terminal_size(PyObject *self, PyObject *args)
 /*[clinic input]
 os.cpu_count
 
-Return the number of CPUs in the system; return None if indeterminable.
+Return the number of CPUs in the system; return None if indeterminable.  This
+number is not equivalent to the number of CPUs the current process can use.
+The number of usable CPUs can be obtained with ``len(os.sched_getaffinity(0))``
 [clinic start generated code]*/
 
 static PyObject *