Bootloader sequence with time prefix

[Valdis.Kletnieks at vt.edu]

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.

The *big* places for improving boot time:

1) Turn off services you don't need.  If you don't need NFS, don't waste
the 0.75 seconds or whatever it takes to load.

2) Use an 'init' process that can multithread better than the old sysvinit
system that runs one startup script at a time.  systemd (for all its other
faults, including a huge learning curve) does this, as does upstart (I'm told).
I've even seen one nice use of 'make -j' as a system startup program.

3) There's a nice program called 'bootchart' that will show you in a graphic
form where your boot time went.  Look at that, plus the kernel and related
message logs, to see where your pauses during system startup are.

4) If feasible, consider the use of an SSD rather than spinning disk.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 865 bytes
Desc: not available
Url : http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20130520/0536f30f/attachment.bin