issue #1404 / linux / phys CPUs count

determine CPUs from /sys/devices/system/cpu/cpu[0-9]/topology/core_id in
case /proc/cpuinfo does not provide this info

3 files changed, 21 insertions, 6 deletions

diff --git a/HISTORY.rst b/HISTORY.rst
index 9e2b5477..217effbd 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -5,6 +5,9 @@
 
 **Enhancements**
 
+- 1404_: [Linux] cpu_count(logical=False) uses a second method (read from
+  `/sys/devices/system/cpu/cpu[0-9]/topology/core_id`) in order to determine
+  the number of physical CPUs in case /proc/cpuinfo does not provide this info.
 - 1458_: provide coloured test output. Also show failures on KeyboardInterrupt.
 - 1464_: various docfixes (always point to python3 doc, fix links, etc.).
 
diff --git a/psutil/_pslinux.py b/psutil/_pslinux.py
index 41be6665..3502f1b1 100644
--- a/psutil/_pslinux.py
+++ b/psutil/_pslinux.py
@@ -627,6 +627,16 @@ def cpu_count_logical():
 
 def cpu_count_physical():
     """Return the number of physical cores in the system."""
+    # Method #1
+    core_ids = set()
+    for path in glob.glob("/sys/devices/system/cpu/cpu[0-9]/topology/core_id"):
+        with open_binary(path) as f:
+            core_ids.add(int(f.read()))
+    result = len(core_ids)
+    if result != 0:
+        return result
+
+    # Method #2
     mapping = {}
     current_info = {}
     with open_binary('%s/cpuinfo' % get_procfs_path()) as f:
@@ -646,8 +656,8 @@ def cpu_count_physical():
                     key, value = line.split(b'\t:', 1)
                     current_info[key] = int(value)
 
-    # mimic os.cpu_count()
-    return sum(mapping.values()) or None
+    result = sum(mapping.values())
+    return result or None  # mimic os.cpu_count()
 
 
 def cpu_stats():
diff --git a/psutil/tests/test_linux.py b/psutil/tests/test_linux.py
index 394ce654..66c50aa6 100755
--- a/psutil/tests/test_linux.py
+++ b/psutil/tests/test_linux.py
@@ -685,10 +685,12 @@ class TestSystemCPUCountPhysical(unittest.TestCase):
                 core_ids.add(fields[1])
         self.assertEqual(psutil.cpu_count(logical=False), len(core_ids))
 
-    def test_emulate_empty_cpuinfo(self):
-        with mock.patch('psutil._common.open', create=True) as m:
-            self.assertIsNone(psutil._pslinux.cpu_count_physical())
-            assert m.called
+    def test_emulate_none(self):
+        with mock.patch('glob.glob', return_value=[]) as m1:
+            with mock.patch('psutil._common.open', create=True) as m2:
+                self.assertIsNone(psutil._pslinux.cpu_count_physical())
+        assert m1.called
+        assert m2.called
 
 
 @unittest.skipIf(not LINUX, "LINUX only")