CPU2 and CPU3 shutdown

[tnkumar]

I am working with a JetBot. During power up, it shows message CPU2: shutdown and CPU3:shutdown. Is this expected? Also, the Jupyter notebook responds very slowly. I ask the motor to stop and it stops after about 2 to 3 minutes. Is this slowness related to the CPUs being shutdown?

[linuxdev]

Don’t know about Jupyter, but the CPU shutdown is normal. Examine this:
cat /proc/cmdline

You will see “isolcpus=1-2”. This is an argument passed to the kernel at boot telling the scheduler that these cores are reserved. Typically you’d do this and then manually schedule your program (using “taskset <core> <app> &”) to use one of those cores. Nothing else would compete for that core.

If you want to use those cores normally (meaning not reserved, but used like any other core), then you could remove the “isolcpus”. Understand that in most cases when a kernel argument appears more than once on the kernel’s command line that only the last use is considered. This means if you add this to the end of the command line the original “isolcpus=1-2” would be ignored:
isolcpus=

You can edit “/boot/extlinux/extlinux.conf”, and look for the “APPEND” key/value pair. It is a single long line of space delimited values. At the end you could add this:
isolcpus=
…and this should cause those cores to schedule normally. Or you could instead dedicate a process/program to the particular core you are interested in using taskset.