Fix cpu freq (#1496)

3 files changed, 42 insertions, 12 deletions

diff --git a/psutil/_pslinux.py b/psutil/_pslinux.py
index c8733e6f..02784602 100644
--- a/psutil/_pslinux.py
+++ b/psutil/_pslinux.py
@@ -708,13 +708,25 @@ elif os.path.exists("/proc/cpuinfo"):
         min and max frequencies are not available and are set to None.
         """
         ret = []
-        with open_binary('%s/cpuinfo' % get_procfs_path()) as f:
-            for line in f:
-                if line.lower().startswith(b'cpu mhz'):
-                    key, value = line.split(b'\t:', 1)
-                    ret.append(_common.scpufreq(float(value), 0.0, 0.0))
+        path = '%s/cpuinfo' % get_procfs_path()
+        if os.path.exists(path):
+            try:
+                with open_binary(path) as f:
+                    for line in f:
+                        if line.lower().startswith(b'cpu mhz'):
+                            key, value = line.split(b'\t:', 1)
+                            ret.append(_common.scpufreq(float(value), 0., 0.))
+            except IOError as err:
+                raise NotImplementedError(
+                    "%r for file %r" % (err, path))
         return ret
 
+else:
+    def cpu_freq():
+        """Dummy implementation when none of the above files are present.
+        """
+        return []
+
 
 # =====================================================================
 # --- network
diff --git a/psutil/tests/test_linux.py b/psutil/tests/test_linux.py
index 4cdc9cbf..a4b79e4f 100755
--- a/psutil/tests/test_linux.py
+++ b/psutil/tests/test_linux.py
@@ -760,6 +760,8 @@ class TestSystemCPUFrequency(unittest.TestCase):
             elif (name.endswith('/scaling_max_freq') and
                     name.startswith("/sys/devices/system/cpu/cpufreq/policy")):
                 return io.BytesIO(b"700000")
+            elif name == '/proc/cpuinfo':
+                return io.BytesIO(b"cpu MHz		: 500")
             else:
                 return orig_open(name, *args, **kwargs)
 
@@ -770,8 +772,12 @@ class TestSystemCPUFrequency(unittest.TestCase):
                     'os.path.exists', return_value=True):
                 freq = psutil.cpu_freq()
                 self.assertEqual(freq.current, 500.0)
-                self.assertEqual(freq.min, 600.0)
-                self.assertEqual(freq.max, 700.0)
+                # when /proc/cpuinfo is used min and max frequencies are not
+                # available and are set to 0.
+                if freq.min != 0.0:
+                    self.assertEqual(freq.min, 600.0)
+                if freq.max != 0.0:
+                    self.assertEqual(freq.max, 700.0)
 
     @unittest.skipIf(not HAS_CPU_FREQ, "not supported")
     def test_emulate_multi_cpu(self):
@@ -795,6 +801,9 @@ class TestSystemCPUFrequency(unittest.TestCase):
             elif (n.endswith('/scaling_max_freq') and
                     n.startswith("/sys/devices/system/cpu/cpufreq/policy1")):
                 return io.BytesIO(b"600000")
+            elif name == '/proc/cpuinfo':
+                return io.BytesIO(b"cpu MHz		: 100\n"
+                                  b"cpu MHz		: 400")
             else:
                 return orig_open(name, *args, **kwargs)
 
@@ -806,11 +815,15 @@ class TestSystemCPUFrequency(unittest.TestCase):
                                 return_value=2):
                     freq = psutil.cpu_freq(percpu=True)
                     self.assertEqual(freq[0].current, 100.0)
-                    self.assertEqual(freq[0].min, 200.0)
-                    self.assertEqual(freq[0].max, 300.0)
+                    if freq[0].min != 0.0:
+                        self.assertEqual(freq[0].min, 200.0)
+                    if freq[0].max != 0.0:
+                        self.assertEqual(freq[0].max, 300.0)
                     self.assertEqual(freq[1].current, 400.0)
-                    self.assertEqual(freq[1].min, 500.0)
-                    self.assertEqual(freq[1].max, 600.0)
+                    if freq[1].min != 0.0:
+                        self.assertEqual(freq[1].min, 500.0)
+                    if freq[1].max != 0.0:
+                        self.assertEqual(freq[1].max, 600.0)
 
     @unittest.skipIf(TRAVIS, "fails on Travis")
     @unittest.skipIf(not HAS_CPU_FREQ, "not supported")
@@ -821,6 +834,8 @@ class TestSystemCPUFrequency(unittest.TestCase):
                 raise IOError(errno.ENOENT, "")
             elif name.endswith('/cpuinfo_cur_freq'):
                 return io.BytesIO(b"200000")
+            elif name == '/proc/cpuinfo':
+                return io.BytesIO(b"cpu MHz		: 200")
             else:
                 return orig_open(name, *args, **kwargs)
 
@@ -841,6 +856,8 @@ class TestSystemCPUFrequency(unittest.TestCase):
                 raise IOError(errno.ENOENT, "")
             elif name.endswith('/cpuinfo_cur_freq'):
                 raise IOError(errno.ENOENT, "")
+            elif name == '/proc/cpuinfo':
+                raise IOError(errno.ENOENT, "")
             else:
                 return orig_open(name, *args, **kwargs)
 
diff --git a/psutil/tests/test_system.py b/psutil/tests/test_system.py
index c4c503a2..eb9016f0 100755
--- a/psutil/tests/test_system.py
+++ b/psutil/tests/test_system.py
@@ -761,7 +761,8 @@ class TestSystemAPIs(unittest.TestCase):
         def check_ls(ls):
             for nt in ls:
                 self.assertEqual(nt._fields, ('current', 'min', 'max'))
-                self.assertLessEqual(nt.current, nt.max)
+                if nt.max != 0.0:
+                    self.assertLessEqual(nt.current, nt.max)
                 for name in nt._fields:
                     value = getattr(nt, name)
                     self.assertIsInstance(value, (int, long, float))