3 ms·

Yes; check my blog post [1] or latest YouTube video [2] for details, but the tldr is 0.4W (80 mA) idle minimum for Zero W, 0.6W (100 mA) idle minimum for Zero W

Yes; check my blog post [1] or latest YouTube video [2] for details, but the tldr is 0.4W (80 mA) idle minimum for Zero W, 0.6W (100 mA) idle minimum for Zero W 2. Zero W goes up to 160 mA at load, while Zero W 2 gets up to 400-500 mA due to the three extra CPU cores. [1] https://www.jeffgeerling.com/blog/2021/look-inside-raspberry-pi-zero-2-w-and-rp3a0-au https://www.jeffgeerling.com/blog/2021/look-inside-raspberry... [2] https://www.youtube.com/watch?v=lKS2ElWQizA https://www.youtube.com/watch?v=lKS2ElWQizA

lloydatkinson 5y ago
That's a big jump. Is there a way of getting Linux to disable a couple of cores?
- hulitu 5y ago
  On x86 there was an option, i think nr_cpus or something like that some time ago. There was also SMP_KERNEL kernel config option.
- rbanffy 5y ago
  `echo 0 > /sys/devices/system/cpu/cpu[0-n]/online` should do what you want.
  - geerlingguy 5y ago
    Even as root, that gives `permission denied` on Pi OS on the Zero 2 W. I'm trying the kernel cmdline option too. Edit: That works! See: https://www.jeffgeerling.com/blog/2021/disabling-cores-reduce-pi-zero-2-ws-power-consumption-half https://www.jeffgeerling.com/blog/2021/disabling-cores-reduc...
    - rbanffy 5y ago
      Well… I said it should, not that it would. ;-)
bullen 5y ago
2W! Did you measure Gflops? I wish you could disable cores dynamically...
- stavros 5y ago
  That's why they called it Pi Zero 2 W and not Pi Zero W 2, which is what it is.
- WithinReason 5y ago
  Is undervolting an option?
- ranger_danger 5y ago
  you can: https://news.ycombinator.com/item?id=29024994 https://news.ycombinator.com/item?id=29024994
- scottlamb 5y ago
  > I wish you could disable cores dynamically... Another comment says /sys/devices/system/cpu/cpu[0-n]/online doesn't work, but I think you can get pretty far by changing the CPU affinity at the cgroup or process levels (for userspace) and on /proc/irq/default_smp_affinity (for interrupts). There are likely some kernel threads that would still run on the other cores, but this is reasonably close. In particular, looks like setting CPUAffinity= /etc/systemd/system.conf will set a default for all of userspace that you can override for particular things as desired.

lloydatkinson 5y ago

That's a big jump. Is there a way of getting Linux to disable a couple of cores?

hulitu 5y ago
On x86 there was an option, i think nr_cpus or something like that some time ago. There was also SMP_KERNEL kernel config option.
rbanffy 5y ago
`echo 0 > /sys/devices/system/cpu/cpu[0-n]/online` should do what you want.
- geerlingguy 5y ago
  Even as root, that gives `permission denied` on Pi OS on the Zero 2 W. I'm trying the kernel cmdline option too. Edit: That works! See: https://www.jeffgeerling.com/blog/2021/disabling-cores-reduce-pi-zero-2-ws-power-consumption-half https://www.jeffgeerling.com/blog/2021/disabling-cores-reduc...
  - rbanffy 5y ago
    Well… I said it should, not that it would. ;-)

bullen 5y ago

2W! Did you measure Gflops? I wish you could disable cores dynamically...

stavros 5y ago
That's why they called it Pi Zero 2 W and not Pi Zero W 2, which is what it is.
WithinReason 5y ago
Is undervolting an option?
ranger_danger 5y ago
you can: https://news.ycombinator.com/item?id=29024994 https://news.ycombinator.com/item?id=29024994
scottlamb 5y ago
> I wish you could disable cores dynamically... Another comment says /sys/devices/system/cpu/cpu[0-n]/online doesn't work, but I think you can get pretty far by changing the CPU affinity at the cgroup or process levels (for userspace) and on /proc/irq/default_smp_affinity (for interrupts). There are likely some kernel threads that would still run on the other cores, but this is reasonably close. In particular, looks like setting CPUAffinity= /etc/systemd/system.conf will set a default for all of userspace that you can override for particular things as desired.