#941: implement cpu_freq() for Linux

psutil/__init__.py

@@ -1846,6 +1846,19 @@ def cpu_stats():
     return _psplatform.cpu_stats()
 
 
+if hasattr(_psplatform, "cpu_freq"):
+
+    def cpu_freq():
+        """Return CPU frequencies as a list of nameduples including
+        current, min and max CPU frequency.
+        The CPUs order is supposed to be consistent with other CPU
+        functions having a 'percpu' argument and returning results for
+        multiple CPUs (cpu_times(), cpu_percent(), cpu_times_percent()).
+        Values are expressed in Mhz.
+        """
+        return _psplatform.cpu_freq()
+
+
 # =====================================================================
 # --- system memory related functions
 # =====================================================================

psutil/_common.py

@@ -156,6 +156,8 @@ class NicDuplex(enum.IntEnum):
 # psutil.cpu_stats()
 scpustats = namedtuple(
     'scpustats', ['ctx_switches', 'interrupts', 'soft_interrupts', 'syscalls'])
+# psutil.cpu_freq()
+scpufreq = namedtuple('scpufreq', ['curr', 'min', 'max'])
 
 # --- for Process methods
 

psutil/_pslinux.py

@@ -9,6 +9,7 @@
 import base64
 import errno
 import functools
+import glob
 import os
 import re
 import socket
@@ -133,6 +134,8 @@ class IOPriority(enum.IntEnum):
     "0B": _common.CONN_CLOSING
 }
 
+_DEFAULT = object()
+
 
 # =====================================================================
 # -- exceptions
@@ -276,6 +279,18 @@ def set_scputimes_ntuple(procfs_path):
     return scputimes
 
 
+def cat(fname, fallback=_DEFAULT, binary=True):
+    """Return file content."""
+    try:
+        with open_binary(fname) if binary else open_text(fname) as f:
+            return f.read()
+    except IOError:
+        if fallback != _DEFAULT:
+            return fallback
+        else:
+            raise
+
+
 try:
     scputimes = set_scputimes_ntuple("/proc")
 except Exception:
@@ -607,6 +622,26 @@ def cpu_stats():
         ctx_switches, interrupts, soft_interrupts, syscalls)
 
 
+if os.path.exists("/sys/devices/system/cpu/cpufreq"):
+
+    def cpu_freq():
+        # scaling_* files seem preferable to cpuinfo_*, see:
+        # http://unix.stackexchange.com/a/87537/168884
+        ret = []
+        ls = glob.glob("/sys/devices/system/cpu/cpufreq/policy[0-9]*")
+        # Sort the list so that '10' comes after '2'. This should
+        # ensure the CPU order is consistent with other CPU functions
+        # having a 'percpu' argument and returning results for multiple
+        # CPUs (cpu_times(), cpu_percent(), cpu_times_percent()).
+        ls.sort(key=lambda x: int(os.path.basename(x)[6:]))
+        for path in ls:
+            curr = int(cat(os.path.join(path, "scaling_cur_freq"))) / 1000
+            max_ = int(cat(os.path.join(path, "scaling_max_freq"))) / 1000
+            min_ = int(cat(os.path.join(path, "scaling_min_freq"))) / 1000
+            ret.append(_common.scpufreq(curr, min_, max_))
+        return ret
+
+
 # =====================================================================
 # --- network
 # =====================================================================

psutil/tests/test_system.py

@@ -697,6 +697,16 @@ def test_cpu_stats(self):
             if name in ('ctx_switches', 'interrupts'):
                 self.assertGreater(value, 0)
 
+    @unittest.skipUnless(hasattr(psutil, "cpu_freq"),
+                         "platform not suported")
+    def test_cpu_freq(self):
+        ls = psutil.cpu_freq()
+        assert ls, ls
+        for nt in ls:
+            for name in nt._fields:
+                value = getattr(nt, name)
+                self.assertGreaterEqual(value, 0)
+
     def test_os_constants(self):
         names = ["POSIX", "WINDOWS", "LINUX", "OSX", "FREEBSD", "OPENBSD",
                  "NETBSD", "BSD", "SUNOS"]