On 05/20/2013 07:40 AM, Valdis.Kletnieks@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.