Bootloader sequence with time prefix (Kernelnewbies Digest, Vol 30, Issue 24)

[lucas.magasweran@ieee.org (Lucas Rangit Magasweran)]

On 05/20/2013 07:40 AM, Valdis.Kletnieks at vt.edu wrote:
> On Mon, 20 May 2013 15:07:33 +0530, Dhyan said:
>> I was working on to measure boottime for  bootime optimization.
> The bootloader is probably not where you're going to find places to 
> optimize.
> It's got two jobs to do - load the kernel and load the initrd. And 
> it's usually
> pretty optimized to do that. About all you can do there is minimize 
> the size of
> the kernel and initrd so there's less to load (and move to SSD if 
> you're really
> hardcore).
>
> The only other place to really win in the boot loader is to set the 
> "hit any
> key to go to the boot menu" timeout to 0 or 1 seconds.  Of course, 
> this means
> you have little (or zero) chance to enter an alternate kernel or 
> commandline.
Valdis is absolutely right.

In case the boot loader is not so optimized or you are trying to reduce 
the boot time by milliseconds try using a GPIO pin and a USB logic 
analyzer (e.g. Salea Logic). Toggle a pin at key places in the boot 
sequence to measure time. Setting up a timer and printing relative time 
over a serial port will negatively impact your boot time.
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