4 ms·

Alright so 27W with heavy peripheral draw then? But 12 W still means it'll be drawing 2.4 amps instead of 1.6 when a random process decides to 100% it. I guess

Alright so 27W with heavy peripheral draw then? But 12 W still means it'll be drawing 2.4 amps instead of 1.6 when a random process decides to 100% it. I guess we can always underclock it. The real unanswered question is, does it finally have a damn sleep mode so it can save power when idle.

pja 3y ago
Jeff Geerling measured 1.8W idle power draw. Based on my experience with previous Pis, I bet you’ll be able to drop that even further by turning off unused board components at boot time.
- moffkalast 3y ago
  True, I've gotten Pi 4s pretty low (< 1W), disabling the LEDs, Ethernet, HDMI, and USB controller, but it's never gonna equal a proper suspend.
  - Fnoord 3y ago
    How did you disable the LED? I mean I can disable LEDs via /proc but not in config.txt correct?
    - pja 3y ago
      Add # Disable Power LED after boot dtparam=pwr_led_activelow=off # Disable SD card activity led dtparam=act_led_trigger=none dtparam=act_led_activelow=off # Disable the ethernet LEDs - these are Pi4 specific values. # Look in the docs for the values for other Pi boards. dtparam=eth_led0=4 dtparam=eth_led1=4 to /boot/config.txt
      - Fnoord 3y ago
        Thank you! It appears to depend on firmware or kernel but for recent kernels (recent 6.1 or 6.2) activelow is no longer necessary [1]. It seems to work on CM4. PS: my bad I disabled the LEDs via /sys not /proc previously: > # for i in /sys/class/leds/*; do echo 0 > "$i/brightness"; done [1] https://github.com/raspberrypi/firmware/issues/1742 https://github.com/raspberrypi/firmware/issues/1742
        doubled112 3y ago
        I've had this drive me crazy. The required lines were different between the Pi 2 and Pi 4 I was using at the time, and the documentation was not updated (or I'd found old docs). An exercise in trial and error.
  - sapiogram 3y ago
    1W is honestly not that great, though. A smartphone will do 10x that out of the box, and still pling for Facebook notifications.
    - nine_k 3y ago
      A smartphone has two entirely separate computers in it, the one that runs Android or iOS, and the baseband controller. The latter is built to be very power-efficient while waiting for a radio signal. It will wake up the dormant application OS computer when a push notification comes in. The same likely can be built on top of an RPi, using, say, wake-on-LAN signaling, or some GPIO as an interrupt source. You'll have to suspend your OS while idle for a prolonged time though.
pipo234 3y ago
I read that the "PC style" power button allows both soft and hard shutdown, so I suppose suspend and hibernate come into the picture as well. It's mostly a matter of OS support, the firmware seems to be there.
- nani8ot 3y ago
  According to Jeff Geerling the Pi 5 doesn't support suspend in firmware, altough it might be possible with an update.
- nfriedly 3y ago
  > soft and hard shutdown My reading of that was: "soft" = trigger an orderly OS shutdown, the same as if you executed `shutdown now` on the command line. "hard" = cut power immediately, as if you just unplugged the power cable.
rollcat 3y ago
> The real unanswered question is, does it finally have a damn sleep mode so it can save power when idle. I dream of DIY'ing a laptop, and RPi looks like a great platform for prototyping that... until you realize there's just no sensible way to put it to sleep. Hibernate + aggressive boot time optimization?
- moffkalast 3y ago
  You know it's funny, my current laptop has a weird firmware bug (certified Asus moment) where it refuses to go into sleep mode. If sleep is triggered by any OS it will straight up just shut down completely. I've lost some work the first few times I used it out of habit. Eventually though it didn't turn out to be much of an issue, SSDs boot real fast these days anyway and I can just do a full power cycle.
  - rollcat 3y ago
    Meanwhile I'm genuinely annoyed that my Thinkpad takes a second or two longer to wake up from sleep than my Mac ;)

pja 3y ago

Jeff Geerling measured 1.8W idle power draw. Based on my experience with previous Pis, I bet you’ll be able to drop that even further by turning off unused board components at boot time.

moffkalast 3y ago
True, I've gotten Pi 4s pretty low (< 1W), disabling the LEDs, Ethernet, HDMI, and USB controller, but it's never gonna equal a proper suspend.
- Fnoord 3y ago
  How did you disable the LED? I mean I can disable LEDs via /proc but not in config.txt correct?
  - pja 3y ago
    Add # Disable Power LED after boot dtparam=pwr_led_activelow=off # Disable SD card activity led dtparam=act_led_trigger=none dtparam=act_led_activelow=off # Disable the ethernet LEDs - these are Pi4 specific values. # Look in the docs for the values for other Pi boards. dtparam=eth_led0=4 dtparam=eth_led1=4 to /boot/config.txt
    - Fnoord 3y ago
      Thank you! It appears to depend on firmware or kernel but for recent kernels (recent 6.1 or 6.2) activelow is no longer necessary [1]. It seems to work on CM4. PS: my bad I disabled the LEDs via /sys not /proc previously: > # for i in /sys/class/leds/*; do echo 0 > "$i/brightness"; done [1] https://github.com/raspberrypi/firmware/issues/1742 https://github.com/raspberrypi/firmware/issues/1742
      - doubled112 3y ago
        I've had this drive me crazy. The required lines were different between the Pi 2 and Pi 4 I was using at the time, and the documentation was not updated (or I'd found old docs). An exercise in trial and error.
- sapiogram 3y ago
  1W is honestly not that great, though. A smartphone will do 10x that out of the box, and still pling for Facebook notifications.
  - nine_k 3y ago
    A smartphone has two entirely separate computers in it, the one that runs Android or iOS, and the baseband controller. The latter is built to be very power-efficient while waiting for a radio signal. It will wake up the dormant application OS computer when a push notification comes in. The same likely can be built on top of an RPi, using, say, wake-on-LAN signaling, or some GPIO as an interrupt source. You'll have to suspend your OS while idle for a prolonged time though.

pipo234 3y ago

I read that the "PC style" power button allows both soft and hard shutdown, so I suppose suspend and hibernate come into the picture as well. It's mostly a matter of OS support, the firmware seems to be there.

nani8ot 3y ago
According to Jeff Geerling the Pi 5 doesn't support suspend in firmware, altough it might be possible with an update.
nfriedly 3y ago
> soft and hard shutdown My reading of that was: "soft" = trigger an orderly OS shutdown, the same as if you executed `shutdown now` on the command line. "hard" = cut power immediately, as if you just unplugged the power cable.

rollcat 3y ago

> The real unanswered question is, does it finally have a damn sleep mode so it can save power when idle. I dream of DIY'ing a laptop, and RPi looks like a great platform for prototyping that... until you realize there's just no sensible way to put it to sleep. Hibernate + aggressive boot time optimization?

moffkalast 3y ago
You know it's funny, my current laptop has a weird firmware bug (certified Asus moment) where it refuses to go into sleep mode. If sleep is triggered by any OS it will straight up just shut down completely. I've lost some work the first few times I used it out of habit. Eventually though it didn't turn out to be much of an issue, SSDs boot real fast these days anyway and I can just do a full power cycle.
- rollcat 3y ago
  Meanwhile I'm genuinely annoyed that my Thinkpad takes a second or two longer to wake up from sleep than my Mac ;)