[gentoo-dev] Multiple emerges at the same time. ("multi-tasking" in portage)

["Miguel S. Filipe" <m3thos@netcabo.pt>]

While reading this,  It reminded me of a thought i allready had.

Why isn't portage more multi-task? What stops it from, while it's busy 
building something, downloading the packages that its going to 
(build/compile/install) next?
 This would speed up the merging process for those with slow internet 
connections, and it would not affect performance I believe. Is there any 
problem with this? Is it just dificult to implement, or its much more 
tricky and  problematic that it seems?

Mikael Hallendal wrote:

>tis 2001-12-04 klockan 14.54 skrev djamil essaissi:
>
>>la classe !
>>
>>portage question number N:
>>will it break anything emerging to independants packages (ebuilds) in
>>the same time ?
>>
>
>No, this is a very nice feature in Portage. Since it doesn't use a
>single shared database file it's no problem. You should look though that
>two seperate emergies doesn't try to install the packages (which might
>cause problems since the second might clean the build directory while
>the first one is working in there).
>
>Regards,
>  Mikael Hallendal
>
But.. in that case, I simply can't do.. since the second can mess up the 
first emerge. Right?

However, paralel emerges would be very nice, In fact.. another thing 
that crossed my mind.. is why doesn't portage,  builds independent 
packages in parallel(at the same time)?
  I'm saying this, because i've noticed in my SMP box, that, even when 
i'm "ebuilding" something, i still have a lot  of CPU idle.. (i used top 
to "check this out") it simply appears that, gcc, make and other apps 
don't take full use of the available CPU.

So, launching multiple ebuilds, and downloading, would use the system 
mutch more efficently, (and obviously, higher loads will make it more 
unsresponsive). There must be a way to take advange of this, without 
having the whole system at his knees (limiting the number of parallel 
ebuilds that would be launched automaticaly, but letting the user run 
has mutch has he pretends to).


Is this really a good idea? If not.. why?
Regards,

Miguel Sousa Filipe