From 96e339369f7ee071fe76ae72ad2a7df9df249f84 Mon Sep 17 00:00:00 2001
From: Guillaume Chazarain <guichaz@gmail.com>
Date: Sun, 23 Aug 2009 17:20:16 +0200
Subject: [PATCH] Added a heuristic to detect kernels without
 CONFIG_TASK_DELAY_ACCT

---
 NEWS          |  1 +
 iotop/data.py |  7 +++++++
 iotop/ui.py   | 12 ++++++++++--
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index 24bc1f7..ed304d1 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,7 @@
 0.3.2
 ~~~~~
 o Split long command lines in the middle instead of cutting them at the end.
+o Added a heuristic to detect kernels without CONFIG_TASK_DELAY_ACCT
 
 0.3.1
 ~~~~~
diff --git a/iotop/data.py b/iotop/data.py
index 0c71315..91bea54 100644
--- a/iotop/data.py
+++ b/iotop/data.py
@@ -56,11 +56,18 @@ class Stats(DumpableObject):
         ('cancelled_write_bytes', 264)
     ]
 
+    has_blkio_delay_total = False
+
     def __init__(self, task_stats_buffer):
         for name, offset in Stats.members_offsets:
             data = task_stats_buffer[offset:offset + 8]
             setattr(self, name, struct.unpack('Q', data)[0])
 
+        # This is a heuristic to detect if CONFIG_TASK_DELAY_ACCT is enabled in
+        # the kernel.
+        if not Stats.has_blkio_delay_total:
+            Stats.has_blkio_delay_total = self.blkio_delay_total != 0
+
     def accumulate(self, other_stats, operator=sum):
         """Returns a new Stats object built from operator(self, other_stats)"""
         delta_stats = Stats.__new__(Stats)
diff --git a/iotop/ui.py b/iotop/ui.py
index 093dc8e..41cfd04 100644
--- a/iotop/ui.py
+++ b/iotop/ui.py
@@ -9,7 +9,7 @@ import struct
 import sys
 import time
 
-from iotop.data import find_uids, TaskStatsNetlink, ProcessList
+from iotop.data import find_uids, TaskStatsNetlink, ProcessList, Stats
 from iotop.version import VERSION
 
 #
@@ -257,7 +257,13 @@ class IOTopUI(object):
                 title = title[:remaining_cols]
                 remaining_cols -= len(title)
                 self.win.addstr(title, attr)
-            for i in xrange(len(lines)):
+            if Stats.has_blkio_delay_total:
+                status_msg = None
+            else:
+                status_msg = ('CONFIG_TASK_DELAY_ACCT not enabled in kernel, '
+                              'cannot determine IO %')
+            num_lines = min(len(lines), self.height - 2 - int(bool(status_msg)))
+            for i in xrange(num_lines):
                 try:
                     self.win.insstr(i + 2, 0, lines[i].encode('utf-8'))
                 except curses.error:
@@ -266,6 +272,8 @@ class IOTopUI(object):
                                        (value, self.win.getmaxyx(), i, lines[i])
                     value = str(value).encode('string_escape')
                     raise exc_type, value, traceback
+            if status_msg:
+                self.win.insstr(self.height - 1, 0, status_msg, curses.A_BOLD)
             self.win.refresh()
 
 def run_iotop_window(win, options):
-- 
2.11.4.GIT