Isolcpus method does not work

Autonomous Machines Jetson & Embedded Systems Jetson Nano
1

Hi,
I want to use one cpu core fore specific app. So I choose isolcpus method.
First, I add ‘isolcpus=1’ to the /boot/extlinux/extlinu.conf file, like

TIMEOUT 30
DEFAULT JetsonIO

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=ttyS0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0

# When testing a custom kernel, it is recommended that you create a backup of
# the original kernel and add a new entry to this file so that the device can
# fallback to the original kernel. To do this:
#
# 1, Make a backup of the original kernel
#      sudo cp /boot/Image /boot/Image.backup
#
# 2, Copy your custom kernel into /boot/Image
#
# 3, Uncomment below menu setting lines for the original kernel
#
# 4, Reboot

# LABEL backup
#    MENU LABEL backup kernel
#    LINUX /boot/Image.backup
#    INITRD /boot/initrd
#    APPEND ${cbootargs}

LABEL JetsonIO
	MENU LABEL Custom Header Config: <HDR40 User Custom [2021-08-31-140311]>
	LINUX /boot/Image
	FDT /boot/kernel_tegra210-p3448-0000-p3449-0000-b00-user-custom.dtb
	INITRD /boot/initrd
	APPEND ${cbootargs} quiet root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 console=ttyS0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0 isolcpus=1

I think there will be appear when I cat the /proc/cmdline, but it does not work

(base) nano@nano-desktop:~$ cat /proc/cmdline 
tegraid=21.1.2.0.0 ddr_die=4096M@2048M section=512M memtype=0 vpr_resize usb_port_owner_info=0 lane_owner_info=0 emc_max_dvfs=0 touch_id=0@63 video=tegrafb no_console_suspend=1 console=ttyS0,115200n8 debug_uartport=lsport,4 earlyprintk=uart8250-32bit,0x70006000 maxcpus=4 usbcore.old_scheme_first=1 lp0_vec=0x1000@0xff780000 core_edp_mv=1125 core_edp_ma=4000 gpt tegra_fbmem=0x800000@0x92ca9000 is_hdmi_initialised=1  earlycon=uart8250,mmio32,0x70006000  root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 console=ttyS0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0

So, after reboot the system, all of the cpu cores were used.

Can you tell me what should I do to realize the isolation?

Yan

3

Hi,
Please try this method on Jetson Nano:
Extlinux.conf: Kernel command line options not appended when using FDT - #3 by JerryChang

4

Thank you. Do you mean this method? Should I flash all the image(remove all data in my system)?

5

Hi,
Please try the method of editing command line in p3448-0000.conf.common and then re-flash the system.

6

ok, will this action delete the data on the old system already?

7

Hi,
Yes, the data will be lost after the clean re-flash. If you have another Jetson Nano, may try it on another device first.

8

Thanks, where can I find a complete re-flash process?

9

Documents are related to a specific release. JetPack/SDK Manager is the software which performs the flash, and L4T (Ubuntu plus NVIDIA drivers) is what actually gets flashed. The two have their release versions tied together. You can see the current L4T release with “head -n 1 /etc/nv_tegra_release”. URLs for the related software:

You can often install the latest major release (for a Nano, JetPack 4.x/L4T R32.x), and pick older releases via starting SDKM like this:
sdkmanager --archivedversions

11

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