Pioneer idle power: Can I get lower idle power by powering off many cores?

Pioneer
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Hi!

I have not tested in person, but I have read online that the MilkV Pioneer’s idle power consumption is circa 59 watts.

This is a bit high for me.

The Pioneer has 64 CPU cores. I think for my particular usecase, 16 or even 10 or 8 CPU cores is enough.

Has anyone checked what happens to the idle power, when running Linux and commanding many CPU cores to power off?

Please share your results.

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Bump @setq @milkv-caravan

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@hoka & @unicornx Do you have any idea here?

Also: If I turn off many cores (e.g. 48, 54 or 56 cores), would / could the total system PCI IO bandwidth be affected or would / could the RAM bandwidth per core be affected (negatively)?

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I will leave this question to engineers from Sophgo.

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@setq @milkv-caravan @hoka Can you clarify this point?

The question is: Can I lower the idle power consumption (and accordingly also the idle heat production) significantly by powering off between fourty-eight and fifty-six CPU cores, so only 8-16 CPU cores are powered on?

Thanks!

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If you want to specifically disable certain CPU cores, you need to edit the dts[1] and set the status of the corresponding CPU cores to “disabled”.

A simple method is to use the dtc[2] command to convert the dtb to dts, modify it, then convert it back to dtb, and finally replace this dtb.

If you just want to limit the number of CPU cores used, you can add “maxcpus=xx” to the boot parameters of /boot/extlinux/extlinux.conf.

[1] https://github.com/milkv-pioneer/linux-riscv/blob/sg2042-dev/arch/riscv/boot/dts/sophgo/mango-cpus-socket0.dtsi

[2] https://manpages.ubuntu.com/manpages/trusty/man1/dtc.1.html

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@setq Can you check quickly, if you set “maxcpus=16”, how much lower idle power consumption does your Pioneer have then? (From how many watts to how many watts)

This will allow us to calculate how many watts each CPU core takes, so we can estimate idle power for any number of CPU cores e.g. 4, 8, 12, 16, 24, etc. .

By the way, not so important but, is it possible to power on and off CPU cores live while the system is running?

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