redirect subprocess output to /dev/null rather than 'PIPE' (#153)

Author: GLEF1X

pyperf/_system.py

@@ -37,10 +37,9 @@ def write_text(filename, content):
 def run_cmd(cmd):
     try:
         # ignore stdout and stderr
-        # FIXME: redirect output to /dev/null
         proc = subprocess.Popen(cmd,
-                                stdout=subprocess.PIPE,
-                                stderr=subprocess.PIPE)
+                                stdout=subprocess.DEVNULL,
+                                stderr=subprocess.DEVNULL)
     except OSError as exc:
         if exc.errno == errno.ENOENT:
             return 127