booting optimization

Willy K. Hamra w.hamra1987 at
Fri Aug 22 10:26:47 UTC 2008

Constantinos Maltezos wrote:
> On Friday 22 August 2008 1:39:59 am O. Sinclair 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!  I wouldn't mind finding more things like
>>> this but my 1525n laptop is now lightning fast upon booting!  ;)
>> I have the same experience! Anyone have an idea what this setting
>> "actually" does/means?
>> Sinclair
> If you've ever watched the console messages during boot, you will see messages 
> telling you that certain things are starting and the like.  Traditionally, all 
> the modules and services and whatnot that get loaded at this time go one after 
> the other, taking turns as it were.  When you enable concurrency, it loads as 
> many of them as it can at once and in that way, the processes run 
> concurrently.  This is why it's faster.  The old way is strictly dependent on 
> processor speed, the concurrent way is dependent on processor speed *and* 
> memory and will almost always be faster.  The only problem I can imagine 
> realistically is if fsck is chosen to run at boot at any point.  But there may 
> be code in the hack that tells everything else to wait until fsck finishes.
the answer is kind of yes, since not ALL scripts are rushed together,
there is different runlevels to consider.
fsck runs in a runlevel where only the root partition is mounted, and
the root partitions itself i take it gets fsck'ed before the rest of the
partitions, so i guess all scripts in the runlevel of fsck, don't need
the hard disk. after the partitions get mounted, the rest of the scripts
are run in their different runlevels AFAIK

Willy K. Hamra
Manager of Hamra Information Systems
Co. Manager of Zeina Computer & Billy Net
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