fourdee4d
Posts: 362
Joined: Mon Sep 17, 2012 10:31 pm
Location: East Midlands, UK
Contact: Website

RPi 3 - Reduce power consumption and heat. Server usage.

Sat Oct 01, 2016 7:23 pm

For server usage, power consumption and heat can be reduced on the RPi 3, without effecting performance.
By lowering GPU related clocks, we can reduce the overall power consumption by 0.2W~. As less power = less heat generated on the ARM, you should also see a benefit of reduced overall heat.
We can also reduce the power consumption further by 0.1W~ by setting headless.

In /boot/config.txt, set the following entries:

Code: Select all

gpu_freq=150
h264_freq=25
isp_freq=25
v3d_freq=25
Here are my test results:
  • RPi 3
  • Performance CPU gov echo -e "performance" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
  • Idle (see attached image for htop process list)
  • Ethernet uses 0.1w when active.
  • Baseline energy consumption = 2.1W
  • gpu_freq=150
    h264_freq=100
    isp_freq=100
    v3d_freq=100
    2.0W
  • gpu_freq=150
    h264_freq=25
    isp_freq=25
    v3d_freq=25
    1.9W
  • Headless:

    Code: Select all

    fbset -xres 16 -yres 16 -vxres 16 -vyres 16 -depth 8
    /opt/vc/bin/tvservice -o
    gpu_freq=100 #Results in no output on HDMI
    h264_freq=25
    isp_freq=25
    v3d_freq=25
    1.8W
This assumes core_freq on the RPi 3 has no effect on CPU performance (eg: like the RPi 1/2 which effects L2 cache): http://elinux.org/RPiconfig.
core_freq = For models prior to the Pi2, this has an impact on ARM performance since it drives the L2 cache.
Attachments
Untitled.png
Untitled.png (45.47 KiB) Viewed 1214 times
DietPi.com - Lightweight justice for your Raspberry Pi. Optimized, simplified linux for everyone
DietPi's web hosting is powered by MyVirtualServer.com

jahboater
Posts: 1931
Joined: Wed Feb 04, 2015 6:38 pm

Re: RPi 3 - Reduce power consumption and heat. Server usage.

Sat Oct 01, 2016 11:40 pm

Thanks for that interesting post.
Why do the fbset - is it just to reduce the memory used?

fourdee4d
Posts: 362
Joined: Mon Sep 17, 2012 10:31 pm
Location: East Midlands, UK
Contact: Website

Re: RPi 3 - Reduce power consumption and heat. Server usage.

Sun Oct 02, 2016 11:16 am

jahboater wrote:Thanks for that interesting post.
Why do the fbset - is it just to reduce the memory used?
RPi memory is shared with GPU. So by reducing the FB (framebuffer) size, reduce bandwidth used by GPU/FB: viewtopic.php?p=105008#p105008
DietPi.com - Lightweight justice for your Raspberry Pi. Optimized, simplified linux for everyone
DietPi's web hosting is powered by MyVirtualServer.com

jahboater
Posts: 1931
Joined: Wed Feb 04, 2015 6:38 pm

Re: RPi 3 - Reduce power consumption and heat. Server usage.

Sun Oct 02, 2016 5:20 pm

Great tip thanks! As someone in the post says even if its only a small improvement, sticking a line in /etc/rc.local is free and simple.

I changed it to: fbset -g 16 16 16 16 8

vale88
Posts: 6
Joined: Mon Sep 26, 2016 7:50 pm

Re: RPi 3 - Reduce power consumption and heat. Server usage.

Mon Oct 03, 2016 4:32 pm

Thanks for sharing. I am always looking for ways (such as sleepy pi) to reduce power usage with Pi.

Valentin S.
Java developer
Interests: JavaFX, NetBeans and Raspberry Pi
Last edited by vale88 on Fri Nov 18, 2016 5:59 pm, edited 1 time in total.

fourdee4d
Posts: 362
Joined: Mon Sep 17, 2012 10:31 pm
Location: East Midlands, UK
Contact: Website

Re: RPi 3 - Reduce power consumption and heat. Server usage.

Mon Oct 03, 2016 5:35 pm

vale88 wrote:Thanks for sharing. I am always looking for ways (such as sleepy pi) to reduce power usage with Pi.
If performance isnt a factor, you can reduce power consumption further by limiting the max CPU clock.

Setting the powersave governor will limit the device to 600mhz:

Code: Select all

echo -e "powersave" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
You can set this in DietPi-Config if your using our optimized image. Applied automatically during boot:
1.jpg
1.jpg (51.31 KiB) Viewed 867 times
DietPi.com - Lightweight justice for your Raspberry Pi. Optimized, simplified linux for everyone
DietPi's web hosting is powered by MyVirtualServer.com

Return to “General discussion”

Who is online

Users browsing this forum: 6by9, Tombosco and 52 guests