5 ms·

I could have sworn I read somewhere that Activity Monitor also included GPU usage in its measurements—naturally, using the GPU more uses more power/battery.

kitsunesoba 11y ago
I imagine that other things like WiFi usage, disk usage, and possibly even port usage could be factored in as well.
- bigiain 11y ago
  I'd also guess backlight.
  - untog 11y ago
    Can apps control backlight level? I can't recall using one that's ever tried.
    - astrange 11y ago
      They can't really on LEDs, though on OLED black is cheaper than other colors. But unnecessary animations (like blinking text cursors) cause the entire graphics hardware stack to wake up all the way to the display, which is a serious power cost.
      - nitrogen 11y ago
        The original CGA/EGA/VGA text modes had a hardware cursor blinking option; I find blinking cursors useful, so it'd be interesting if modern GPUs added a low-power animation loop feature.
        astrange 11y ago
        Their power cost is actually a pretty recent development. It used to be that it didn't matter because the display refreshed every frame no matter what, but in the last few years laptop displays added panel self-refresh. If the screen becomes static for a little while, the host side can stop driving it entirely and it'll keep the same picture up. I'd guess it wouldn't be hard to keep two frames in memory, so you could get one blink at a time.
    - hobs 11y ago
      What about f.lux?
      - nroach 11y ago
        color temperature, not backlight level.
        cbsmith 11y ago
        ...and ironically the way f.lux works means it stresses out the GPU more when it is adjusting colour temperature, so...
        jevinskie 11y ago
        Except when it is transitioning color temperatures, I don't see why this would be the case. I reversed f.lux and it just calls some UpdateRGBLUT type function based on the color temperature. I think this LUT is applied to the frame buffer (perhaps this is how color profiles work?) even if f.lux is not being used.
        cbsmith 11y ago
        First, f.lux periodically adjusts the LUT, so it does call this fairly often. Secondly, in my experience, adding this functionality seriously increases the odds that my laptop will switch from using the Intel GPU to the Nvidia GPU.
        lcswi 11y ago
        Are you sure? I use redshift and it can control the backlight in addition to the color I believe.
comex 11y ago
It does. I found a list of factors and posted it as a comment on the blog post: https://blog.mozilla.org/nnethercote/2015/08/26/what-does-the-os-x-activity-monitors-energy-impact-actually-measure/comment-page-1/#comment-46775 https://blog.mozilla.org/nnethercote/2015/08/26/what-does-th... In the data I posted, which is from /usr/share/pmenergy/default.plist, kgpu_time is 0.0, but in all the other plists it's nonzero.
- ejdyksen 11y ago
  Oh wow, nice find. It looks like that calculation is pretty comprehensive, then.
- nnethercote 11y ago
  I've updated the post to incorporate your findings. Thank you!
zurn 11y ago
Or possibly saves power, if work is being offloaded from the CPU.

kitsunesoba 11y ago

I imagine that other things like WiFi usage, disk usage, and possibly even port usage could be factored in as well.

bigiain 11y ago
I'd also guess backlight.
- untog 11y ago
  Can apps control backlight level? I can't recall using one that's ever tried.
  - astrange 11y ago
    They can't really on LEDs, though on OLED black is cheaper than other colors. But unnecessary animations (like blinking text cursors) cause the entire graphics hardware stack to wake up all the way to the display, which is a serious power cost.
    - nitrogen 11y ago
      The original CGA/EGA/VGA text modes had a hardware cursor blinking option; I find blinking cursors useful, so it'd be interesting if modern GPUs added a low-power animation loop feature.
      - astrange 11y ago
        Their power cost is actually a pretty recent development. It used to be that it didn't matter because the display refreshed every frame no matter what, but in the last few years laptop displays added panel self-refresh. If the screen becomes static for a little while, the host side can stop driving it entirely and it'll keep the same picture up. I'd guess it wouldn't be hard to keep two frames in memory, so you could get one blink at a time.
  - hobs 11y ago
    What about f.lux?
    - nroach 11y ago
      color temperature, not backlight level.
      - cbsmith 11y ago
        ...and ironically the way f.lux works means it stresses out the GPU more when it is adjusting colour temperature, so...
        jevinskie 11y ago
        Except when it is transitioning color temperatures, I don't see why this would be the case. I reversed f.lux and it just calls some UpdateRGBLUT type function based on the color temperature. I think this LUT is applied to the frame buffer (perhaps this is how color profiles work?) even if f.lux is not being used.
        cbsmith 11y ago
        First, f.lux periodically adjusts the LUT, so it does call this fairly often. Secondly, in my experience, adding this functionality seriously increases the odds that my laptop will switch from using the Intel GPU to the Nvidia GPU.
      - lcswi 11y ago
        Are you sure? I use redshift and it can control the backlight in addition to the color I believe.

comex 11y ago

It does. I found a list of factors and posted it as a comment on the blog post: https://blog.mozilla.org/nnethercote/2015/08/26/what-does-the-os-x-activity-monitors-energy-impact-actually-measure/comment-page-1/#comment-46775 https://blog.mozilla.org/nnethercote/2015/08/26/what-does-th... In the data I posted, which is from /usr/share/pmenergy/default.plist, kgpu_time is 0.0, but in all the other plists it's nonzero.

ejdyksen 11y ago
Oh wow, nice find. It looks like that calculation is pretty comprehensive, then.
nnethercote 11y ago
I've updated the post to incorporate your findings. Thank you!

zurn 11y ago

Or possibly saves power, if work is being offloaded from the CPU.