booting optimization

[Willy K. Hamra]

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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