CPU Clock frequency at boot time - Nvidia Jetson TK1

Robotics & Edge Computing Jetson & Embedded Systems Jetson TK1
1

Hello Developers ,

Currently I am working on an embedded project using Tegra Jetson Tk1 board. The Linux Kernel version is 4.7 and the u-boot version is v2016.05. I am building a customized Linux kernel and u-boot to have the fastest boot time possible.

During Kernel startup I am seeing some error messages related to CPU clock frequencies like,

[ 0.000000] Tegra clk 127: register failed with -17
[ 4.275805] cpufreq: cpufreq_online: CPU0: Running at unlisted freq:
696000 KHz
[ 4.275845] cpufreq: cpufreq_online: CPU0: Unlisted initial frequency
changed to: 714000 KHz

On seeing the bootchart I have a feeling that the cpu clock frequency might be low - as lot of drivers are taking more time than usual, so now I wish to know what frequency does the cpu cores are running on during boot time. I am not clear on who is responsible(u-boot/kernel) for setting up the cpu clock frequency during the boot time.

Any suggestions on how to know the cpu frequency during boot time will be helpful. Please note that I have disabled all other governors except performance. After the startup when I check the frequency its showing 2320500 which is fine, but I want to know during the boot phase what frequency does it run on and which module sets the frequency

root@jetsontk1:~# cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq
2320500
2320500
2320500
2320500

Thanks & Regards,
Vinothkumar

2

Hi Vinoth,

Jetson-tk1 uses userspace governor as a default governor while bootup. It is possible to change default governor to performance to boost the boot time. Please disable kernel config CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE and then enable CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE to use performance governor during bootup with max CPU clock frequency.

3

The user space “on demand” can also be taken out of the picture:

sudo update-rc.d -f ondemand remove

…having that in place tends to sometimes countermand scripts or settings to performance mode. Removing means what you set will stick.