The system starts too slowly

JetsonNano with jp4.3,It takes 40 seconds for the system to start。I want to speed up to 25 seconds。Who has an idea?

What is your definition of system finishes the boot?

Because I have another development board connected to JetsonNano through serial port, and that development board only takes 20 seconds to start.I want to speed up to 20 seconds。

I meant, when did you count the system is done booting?

For example, actually, the system is ready when you see UART console or ssh is available.
Some people consider this as system done booting because they are using headless setup.

While some others may think the system is done when desktop is showing up.

Which case is yours?

I have turned on the Linux command line mode and let my program start automatically.However It still takes 25 seconds for the system to start。I want 20 seconds.

Ok, so is it a headless case? Does your application require any other dependencies that it has to wait up for them?

Have you disabled the wait time in uboot?

My application require nothing。How to disabled the wait time in uboot? It may help me a lot。

When you boot up, interrupt the uboot so that it will enter interactive mode.

Then, use below commands.

setenv bootdelay 0
saveenv

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How to interrupt the uboot ?

Use uart, keyboard and your finger.

Type anything when your see uboot starts on UART console.

Thanks a lot。

Is there any other way to save time?

Will share the method later. It is more complicated.

Please let me know if there is a new way. Thank you。

What is your current boot time?

FYI, if you don’t know where the time is consumed it can be very hard to reduce boot time. A full serial console boot log, after you’ve done any of the above changes previously checked, would be a useful tool to see where the time is consumed. Serial console boot logs contain timestamps.

I almost forgot to mention: If you have one model of Nano with eMMC, and the other with SD card, then boot time will change depending on memory speed, and there isn’t much which can be done about that. If both are SD card models of Nano, then boot times can change drastically depending on the SD card itself.

Now I takes 22 seconds for the system to start.Just two more seconds.

I use a high-speed SD card(120M/s)。
I use the original operating system(jp4.3), no changes.
Now It takes 22 seconds for the system to start.Use the following two ways:
1、Turn on the Linux command line mode and let my program start automatically.
2、Cancel the uboot wait time。

A verbose serial console boot log would show where time is spent. There isn’t much that can be done to speed things up without knowing which parts are slowing it down. Serial console shows timestamps even in bootloader stages, so it is particularly useful. See:
https://www.jetsonhacks.com/2019/04/19/jetson-nano-serial-console/