Minimal system boot time: 300 ms [LWN.net]

Minimal system boot time: 300 ms

Posted Apr 3, 2011 0:54 UTC (Sun) by giraffedata (subscriber, #1954)
In reply to: Quotes of the week by anselm
Parent article: Quotes of the week

I agree that this system is hardly functional -- the only function it has is the ability to extend the system to add some real function, like taking pictures or making phone calls. But I think it is still a highly useful benchmark, because it covers the common part of all these possible systems, and a part which has traditionally taken much longer.

The benchmark also omits the other end -- getting the system up to the boot loader. So it's just a measurement of kernel start time, and the only function expected of a kernel is to run applications.

It would be nice if they would follow it up with an example of a realistic application and tell how long it takes from e.g. power button to view finder active. Because maybe the kernel boot time isn't all that significant after all.

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Minimal system boot time: 300 ms

Posted Apr 3, 2011 1:25 UTC (Sun) by jengelh (subscriber, #33263) [Link]

>Because maybe the kernel boot time isn't all that significant after all.

Indeed not, as has been observed before - https://lwn.net/Articles/299483/

Minimal system boot time: 300 ms

Posted Apr 3, 2011 16:38 UTC (Sun) by mgedmin (subscriber, #34497) [Link]

The website mentioned in the email (http://www.makelinux.com/emb/fastboot/omap) mentions the time spent before the bootloader:

> Boot analysis
> Logging starts at 70 ms from reset. Boot time from reset is 300 + 70 = 370 ms.
> Logging starts at 330 ms from power on. Cold boot time is 330 + 300 = 630 ms.
> Loading of 1.5 MiB Linux image from NAND takes 237 ms with throughput 6 MiB/s.
> Code execution takes 60 ms or 43M CPU cycles. (For other CPU frequency execution time is different, but number of processor cycles is the same)

I agree that it would be interesting to see timings for a sample application as well.

I seem to recall one example of embedded Linux starting a GUI application (Qt over framebuffer IIRC) driving a webcam in about 1 second (again, IIRC) from system reset.