Issue #12655: Mention multiprocessing.cpu_count() in os.sched_getaffinity() doc
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 59ff3eb..40c2887 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -3153,6 +3153,10 @@
    Return the set of CPUs the process with PID *pid* (or the current process
    if zero) is restricted to.
 
+   .. seealso::
+      :func:`multiprocessing.cpu_count` returns the number of CPUs in the
+      system.
+
 
 .. _os-path: