Description of problem:
When using mom on a ovirt managed host, and when it runs ksm because of mom policy, vdsClient getVdsStats returns every growing value for ksmCpu, which is supposed to be a cpu percentage, and eventually breaks ovirt-engine-dwhd because it becomes greater than an int.

Version-Release number of selected component (if applicable):
ovirt engine 3.2.2 - 1.1.fc18
vdsm 4.10.3 - 17.fc18
mom  0.3.0 - 1.fc18

How reproducible:

run an ovirt managed host with memory pressure to start ksm. Run vdsClient -s 0 getVdsStats repeatedly to watch the ksmCpu value increase over time.


Steps to Reproduce:
1.
2.
3.

Actual results:
should be percentage of cpu, but grows unbounded

Expected results:


Additional info:

It looks like a bug in mom's HostKSM.py where last_jiff used to calculate difference in jiffies is never reset.
A change to set last_jiff to curr_jiff in get_ksmd_cpu_usage fixes it for me

[root@vm7 Collectors]# diff -C 4 HostKSM.py~ HostKSM.py
*** HostKSM.py~ 2012-10-05 13:37:16.000000000 -0400
--- HostKSM.py  2013-08-21 13:09:49.782064019 -0400
***************
*** 71,78 ****
--- 71,79 ----
          # wrap-around into account.
          interval_jiffs = (cur_jiff - self.last_jiff) % 2**32
          total_jiffs = os.sysconf('SC_CLK_TCK') * self.interval
          # Calculate percentage of total jiffies during this interval.
+         self.last_jiff = cur_jiff
          return 100 * interval_jiffs / total_jiffs

      def get_shareable_mem(self):
          """