Disable cpu hotplug on Hikey960


#1

Hi,

Can you please let me know how to disable cpu hotplug on Hikey960.
And also to increase cpu performance by applying any tunnables.

Thanks


#2

Hi @Anonymous,

Now we have no any hotplug dynamic mechanism on Hikey960 (such like hotplug governor); the system keeps to run 8 cores simultaneously. So I don’t know clearly what’s your question meaning.

For what it worth, you could use command to hotplug off any specific CPU and hotplug in it again:

echo 0 > /sys/devices/system/cpu/cpuX/online
echo 1 > /sys/devices/system/cpu/cpuX/online

You could adjust the “sustainable_power” to a bigger value so can loose thermal throttling for CPU frequency; if you set “99999999” to sustainable power, this can let thermal framework doesn’t impose limitation on CPU frequency:

echo 99999999 > /sys/class/thermal/thermal_zone0/sustainable_power


#3

You could adjust the “sustainable_power” to a bigger value so can loose thermal throttling for CPU frequency; if you set “99999999” to sustainable power, this can let thermal framework doesn’t impose limitation on CPU frequency:

echo 99999999 > /sys/class/thermal/thermal_zone0/sustainable_power

Having said that the most obvious “tuneable” if you are trying to do
benchmarking of the cores is to fit a very large heat sink and a fan!

IIRC if you get the chip too hot then regardless of what performance
level the kernel asks for the SoC will enter a kind of "limp mode"
to prevent itself from burning up.

Daniel.


#4

Thanks for Daniel’s reminding. I should mention this ahead.