Add function for dropping caches.

1 files changed, 15 insertions, 1 deletions

diff --git a/seivot b/seivot
index 4709c1d..66c696c 100755
--- a/seivot
+++ b/seivot
@@ -47,11 +47,25 @@ def runcmd(argv, **kwargs):
     data = os.read(fd, 1024**2)
     os.close(fd)
     if p.returncode != 0:
-        raise Exception('command failed: %s\n%s' % (argv, err))
+        raise cliapp.AppException('command failed: %s\n%s' % (argv, err))
 
     return Measurement(data), out
 
 
+def drop_caches():
+    def sudo_tee(status):
+        p = subprocess.Popen(['sudo', '-p', 'Password (for clearing cache): ',
+                              'tee', '/proc/sys/vm/drop_caches'],
+                             stdin=subprocess.PIPE, stdout=subprocess.PIPE)
+        out, err = p.communicate('%s\n' % status)
+        if p.returncode != 0:
+            raise cliapp.AppException('failed to clear cache')
+
+    logging.debug('clearing Linux kernel cache')
+    sudo_tee(3)
+    sudo_tee(0)
+
+
 class BackupProgram(object):
 
     name = None