booting optimization

Nils Kassube kassube at
Fri Aug 22 11:20:26 UTC 2008

Willy K. Hamra wrote:
> Nils Kassube wrote:
> > Pastor JW wrote:
> >> I came across this while looking through /etc/init.d/rc to see what
> >> things do. There is a line which is "CONCURRENCY=none" there so I
> >> changed the "none" to "shell" like the comment indicates is a viable
> >> option and booting became MUCH faster!
> >
> > Thanks for the tip, but there is no measurable difference here, it is
> > 52s with both "none" and "shell" from grub menu until login screen.
> > The only difference I see is that many boot messages are displayed
> > twice when using the "shell" option.
> if i'm not mistaken, this option means if we want the boot-time scripts
> and programs to be run one after the other, like a list or something,
> or if we want them concurrent, all running together. if this is what it
> means, them people who would notice the most difference are people with
> more than 1 processor (dual core, hyper threading, etc...) since the
> scripts can be run 2 by 2, whereas on single processor computers, all
> the scripts will rush together, will fight for IO resources (like hard
> disk) and will slow each other down.
> for me, i noticed a 5~10 seconds difference, from grub to kdm used to
> take 20~25 seconds, now around 15 seconds.

Good point. So I repeated the test with my dual core machine and indeed 
there was an improvement of 3s with CONCURRENCY set to shell.


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