Re: [gentoo-user] Emerge and CPU core usage

[Peter Humphrey]

On Monday, 9 December 2019 06:31:08 GMT Dale wrote:
> Howdy,
>
> As some may recall, I upgraded my rig to a 8 core CPU, expanded memory,
> added a hard drive etc etc a while back.  All of which made things a bit
> faster.  Each core isn't that much faster but the extra cores certainly
> help in most cases.  It is a noticeable improvement.  There's one thing
> tho that it just doesn't help much on.  That thing is the emerge command
> itself.  When I run emerge, based on gkrellm etc, it always uses one
> core and that's it.  As one knows, emerge can take a while trying to
> figure out the best way to upgrade, especially when something is causing
> a road block and requires a detour.  Will portage ever be able to use
> more than one core?  I'd suspect that if it could use all available
> cores, it would speed things up quite a bit.  It may not be 8 times
> faster in my case but even 4 times faster would be nice, more even
> better.  Others that have more cores/threads/whatever could see a even
> larger speed increase.
>
> I'm sure trying to get portage to do things in parallel would be a
> programmers nightmare.  It may not even be doable given how the tree is
> done or that the complexity of calculating all the options is just to
> much to run in parallel.  Still, does anyone think it will be possible
> at some point?  Anyone else think it would be as awesome as I do?
> Anyone know if it is something that is being worked on?  I think I read
> on -dev once long ago about this but can't recall details and I'm not
> aware of any movement in that direction.  I haven't seen any mention of
> it in a long while now.

Portage does indeed run as many emerge jobs as you have cores, if you let it, 
but not the calculation of dependencies. That, as you say, cannot be divided 
into pieces to give to separate cores, and I'm sure it never will be. Pity, 
because on a slow machine like my 32-bit Atom box, it takes ages.

-- 
Regards,
Peter.