зеркало из https://github.com/mozilla/gecko-dev.git
57 строки
2.8 KiB
Markdown
57 строки
2.8 KiB
Markdown
# Intel Power Gadget
|
|
|
|
[Intel Power Gadget](https://software.intel.com/en-us/articles/intel-power-gadget/)
|
|
provides real-time graphs of various power-related measures and
|
|
estimates, all taken from the Intel RAPL MSRs. This article provides a
|
|
basic introduction.
|
|
|
|
**Note**: The [power profiling
|
|
overview](power_profiling_overview.md) is
|
|
worth reading at this point if you haven\'t already. It may make parts
|
|
of this document easier to understand.
|
|
|
|
The main strengths of this tool are (a) it works on Windows, unlike most
|
|
other power-related tools, and (b) it shows this data in graph form,
|
|
which is occasionally useful. On Mac and Linux, `tools/power/rapl`
|
|
[](tools_power_rapl.md) is probably a better tool
|
|
to use.
|
|
|
|
## Understanding the Power Gadget output
|
|
|
|
The following screenshot (from the Mac version) demonstrates the
|
|
available measurements.
|
|
|
|
|
|
|
|
The three panes display the following information:
|
|
|
|
- **Power**: Shows power estimates for the package and the cores
|
|
(\"IA\"). These are reasonably useful for power profiling purposes,
|
|
but Mozilla\'s `rapl` utility provides these along with GPU and RAM
|
|
estimates, and in a command-line format that is often easier to use.
|
|
- **Frequency**: Shows operating frequency measurements for the cores
|
|
(\"IA\") and the GPU (\"GT\"). These measurements aren\'t
|
|
particularly useful for power profiling purposes.
|
|
- **Temperature**: Shows the package temperature. This is interesting,
|
|
but again not useful for power profiling purposes. Specifically,
|
|
the temperature is a proxy measurement that is *affected by*
|
|
processor power consumption, rather than one that *affects* it,
|
|
which makes it even less useful than most proxy measurements.
|
|
|
|
Intel Power Gadget can also log these results to a file. This feature
|
|
has been used in [energia](https://github.com/mozilla/energia), Roberto
|
|
Vitillo\'s tool for systematically measuring differential power usage
|
|
between different browsers. (An energia dashboard can be seen
|
|
[here](http://people.mozilla.org/~rvitillo/dashboard/); please note that
|
|
the data has not been updated since early 2014.)
|
|
|
|
Version 3.0 (available on Mac and Windows, but not on Linux) also
|
|
exposes an API from which the same measurements can be extracted
|
|
programmatically. At one point the Gecko Profiler [used this
|
|
API](https://benoitgirard.wordpress.com/2012/06/29/correlating-power-usage-with-performance-data-using-the-gecko-profiler-and-intel-sandy-bridge/)
|
|
on Windows to implement experimental package power estimates.
|
|
Unfortunately, the Gecko profiler takes 1000 samples per second on
|
|
desktop and is CPU intensive and so is likely to skew the RAPL estimates
|
|
significantly, so the API integration was removed. The API is otherwise
|
|
unlikely to be of interest to Mozilla developers.
|