How to re-enable CPU Cores after isolcpus

I’m running some processes on a Jetson NX and I was trying to isolate 3 of the cores so I could use taskset and dedicate them to my python script which incorporated multi processing. To do this, I followed a few tutorials and modified my /boot/extlinux/extlinux.conf file to be:

TIMEOUT 30
DEFAULT primary

MENU TITLE L4T boot options

LABEL primary
      MENU LABEL primary kernel
      LINUX /boot/Image
      INITRD /boot/initrd
      APPEND ${cbootargs} quiet root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 console=ttyTCU0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0 isolcpus=3-5

This worked fine for my needs and when I ran cat /sys/devices/system/cpu/isolated it outputted 3-5 . Now I’m trying to bring back cores 3 and 4, so I modified the extlinux.conf file to say:

TIMEOUT 30
DEFAULT primary

MENU TITLE L4T boot options

LABEL primary
      MENU LABEL primary kernel
      LINUX /boot/Image
      INITRD /boot/initrd
      APPEND ${cbootargs} quiet root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 console=ttyTCU0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0 isolcpus=5

and I rebooted my Jetson. However It still says cores 3-5 are isolated. Is there some other steps I need to take to re-enable these cores?

What gives ?

cat /proc/cmdline

If it shows your command line, then some other software went to disable other cores.
Be sure you use a nvpmodel enabling all cores such as nvpmodel -m 2 on NX.

If it shows anything else, then your config was not booted and it reverted to some other config.

I completely removed the isolcpus and rebooted the jetson. Now it shows that only core 5 is isolated. The output of the command is:
console=ttyTCU0,115200 video=tegrafb earlycon=tegra_comb_uart,mmio32,0x0c168000 gpt rootfs.slot_suffix= usbcore.old_scheme_first=1 tegraid=19.1.2.0.0 maxcpus=6 boot.slot_suffix=_b boot.ratchetvalues=0.4.2 vpr_resize sdhci_tegra.en_boot_part_access=1 quiet root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 console=ttyTCU0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0 isolcpus=5

I just rebooted again and all 6 cores are available again, not sure why it needed to be rebooted twice but it works now