This paladin run failed:
    https://luci-milo.appspot.com/buildbot/chromeos/nyan_big-paladin/3880

The failure was because of this test:
    http://cautotest-prod.corp.google.com/afe/#tab_id=view_job&object_id=163699290

That test failed because of this:
Traceback (most recent call last):
  File "/usr/local/autotest/common_lib/test.py", line 831, in _call_test_function
    return func(*args, **dargs)
  File "/usr/local/autotest/common_lib/test.py", line 495, in execute
    dargs)
  File "/usr/local/autotest/common_lib/test.py", line 362, in _call_run_once_with_retry
    postprocess_profiled_run, args, dargs)
  File "/usr/local/autotest/common_lib/test.py", line 400, in _call_run_once
    self.run_once(*args, **dargs)
  File "/usr/local/autotest/tests/graphics_Idle/graphics_Idle.py", line 48, in run_once
    if not utils.wait_for_idle_cpu(20.0, 0.1):
  File "/usr/local/autotest/bin/utils.py", line 1640, in wait_for_idle_cpu
    compute_active_cpu_time(cpu_usage_start, cpu_usage_end)
  File "/usr/local/autotest/bin/utils.py", line 1612, in compute_active_cpu_time
    (total_time_end - total_time_start))
ZeroDivisionError: float division by zero

Here's the source code around the failure:
    def compute_active_cpu_time(cpu_usage_start, cpu_usage_end):
        idle_cols = ('idle', 'iowait')  # All other cols are calculated as active.    
        time_active_start = sum([x[1] for x in cpu_usage_start.iteritems()
                                 if x[0] not in idle_cols])
        time_active_end = sum([x[1] for x in cpu_usage_end.iteritems()
                               if x[0] not in idle_cols])
        total_time_start = sum(cpu_usage_start.values())
        total_time_end = sum(cpu_usage_end.values())
        return ((float(time_active_end) - time_active_start) /
                (total_time_end - total_time_start))

So, the error happened because the routine's estimate of "time
elapsed" was calculated to be 0.

Assigning to a sheriff to figure out who owns this test.  There's a
good chance that ihf@ knows the answer...