[Telemetry] Add power usage metric

[Telemetry] Add power usage metric

* Add a power usage metric and add sample usage in startup test.
* OS X: Only print power metrics stderr output when passing -v to Telemetry due to console spew.

BUG=336565, 336672, 336555
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=247100

[tonyg, 2014-01-23 18:23:40]

https://codereview.chromium.org/144543007/diff/1/tools/perf/measurements/star...
File tools/perf/measurements/startup.py (right):

https://codereview.chromium.org/144543007/diff/1/tools/perf/measurements/star...
tools/perf/measurements/startup.py:21: self._power_metric = None
startup represents such a fleeting period that it isn't clear to me whether
there is value in measuring our efficiency during startup.

I suggested some metrics which I do think benefit from power measurement here:
https://code.google.com/p/chromium/issues/detail?id=336672

But perhaps we want to use the metric in a follow-up CL just in case something
breaks, then we don't have to worry about reverting the Metric itself.

https://codereview.chromium.org/144543007/diff/1/tools/perf/metrics/power.py
File tools/perf/metrics/power.py (right):

https://codereview.chromium.org/144543007/diff/1/tools/perf/metrics/power.py#...
tools/perf/metrics/power.py:23: self._backend =
platform.CreatePlatformBackendForCurrentOS()
We should access this via tab.browser.platform and not store a reference to it.

https://codereview.chromium.org/144543007/diff/1/tools/perf/metrics/power.py#...
tools/perf/metrics/power.py:27: "Reusing a power profiler is not supported")
Why? Shouldn't we just clear self._results in AddResults()?

https://codereview.chromium.org/144543007/diff/1/tools/perf/metrics/power.py#...
tools/perf/metrics/power.py:47: results.Add('energy_consumption_mwh', 'mwh',
energy_consumption_mwh)
For the unit display string, let's use the correct capitalization: mWh.

Also, we'll need to add mWh to tools/perf/unit-info.json in order for the
dashboard to know that lower is better.

https://codereview.chromium.org/144543007/diff/1/tools/telemetry/telemetry/co...
File tools/telemetry/telemetry/core/platform/mac_platform_backend.py (right):

https://codereview.chromium.org/144543007/diff/1/tools/telemetry/telemetry/co...
tools/telemetry/telemetry/core/platform/mac_platform_backend.py:43: if
logging.getLogger().getEffectiveLevel() > logging.INFO:
Nice! Thanks for adding this. In other places, we've coded it as:

if logging.getLogger().isEnabledFor(logging.DEBUG):
  ...

[jeremy, 2014-01-23 18:58:41]

https://codereview.chromium.org/144543007/diff/1/tools/perf/measurements/star...
File tools/perf/measurements/startup.py (right):

https://codereview.chromium.org/144543007/diff/1/tools/perf/measurements/star...
tools/perf/measurements/startup.py:21: self._power_metric = None
On 2014/01/23 18:23:40, tonyg wrote:
> startup represents such a fleeting period that it isn't clear to me whether
> there is value in measuring our efficiency during startup.
> 
> I suggested some metrics which I do think benefit from power measurement here:
> https://code.google.com/p/chromium/issues/detail?id=336672
> 
> But perhaps we want to use the metric in a follow-up CL just in case something
> breaks, then we don't have to worry about reverting the Metric itself.

Done.

https://codereview.chromium.org/144543007/diff/1/tools/perf/metrics/power.py
File tools/perf/metrics/power.py (right):

https://codereview.chromium.org/144543007/diff/1/tools/perf/metrics/power.py#...
tools/perf/metrics/power.py:23: self._backend =
platform.CreatePlatformBackendForCurrentOS()
On 2014/01/23 18:23:40, tonyg wrote:
> We should access this via tab.browser.platform and not store a reference to
it.

Done.

https://codereview.chromium.org/144543007/diff/1/tools/perf/metrics/power.py#...
tools/perf/metrics/power.py:27: "Reusing a power profiler is not supported")
On 2014/01/23 18:23:40, tonyg wrote:
> Why? Shouldn't we just clear self._results in AddResults()?

Done.

https://codereview.chromium.org/144543007/diff/1/tools/perf/metrics/power.py#...
tools/perf/metrics/power.py:47: results.Add('energy_consumption_mwh', 'mwh',
energy_consumption_mwh)
On 2014/01/23 18:23:40, tonyg wrote:
> For the unit display string, let's use the correct capitalization: mWh.
> 
> Also, we'll need to add mWh to tools/perf/unit-info.json in order for the
> dashboard to know that lower is better.

Done.

https://codereview.chromium.org/144543007/diff/1/tools/telemetry/telemetry/co...
File tools/telemetry/telemetry/core/platform/mac_platform_backend.py (right):

https://codereview.chromium.org/144543007/diff/1/tools/telemetry/telemetry/co...
tools/telemetry/telemetry/core/platform/mac_platform_backend.py:43: if
logging.getLogger().getEffectiveLevel() > logging.INFO:
On 2014/01/23 18:23:40, tonyg wrote:
> Nice! Thanks for adding this. In other places, we've coded it as:
> 
> if logging.getLogger().isEnabledFor(logging.DEBUG):
>   ...

Done.

[tonyg, 2014-01-23 19:11:24]

lgtm

https://codereview.chromium.org/144543007/diff/80001/tools/perf/unit-info.json
File tools/perf/unit-info.json (right):

https://codereview.chromium.org/144543007/diff/80001/tools/perf/unit-info.jso...
tools/perf/unit-info.json:73: "why": "Fewer mWh means less power."
Let's say: "Fewer milliwatt-hours means less energy consumed."

https://codereview.chromium.org/144543007/diff/80001/tools/telemetry/telemetr...
File tools/telemetry/telemetry/core/platform/mac_platform_backend.py (right):

https://codereview.chromium.org/144543007/diff/80001/tools/telemetry/telemetr...
tools/telemetry/telemetry/core/platform/mac_platform_backend.py:43: if
logging.getLogger().isEnabledFor(logging.INFO):
The bots enable INFO, and we probably don't want the spam there, right? Should
this be DEBUG instead?

[tonyg, 2014-01-23 21:32:46]

lgtm

per offline discussion, --report-root-metrics.

[commit-bot: I haz the power, 2014-01-24 22:48:44]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jeremy@chromium.org/144543007/250001

[commit-bot: I haz the power, 2014-01-25 07:59:45]

Change committed as 247100