Re: [gentoo-dev] Packages up for grabs

[Zac Medico]

On 06/16/2013 11:23 AM, Tom Wijsman wrote:
> Ignoring that call graph, you could look at what has recently been
> introduced to increase the amount of time needed to calculate the
> dependency graph; you don't have to look far.
>
> http://blogs.gentoo.org/mgorny/2013/05/27/the-pointless-art-of-subslots/
>
> While I don't want point out the contents of that blog post, the title
> is relevant; implementing features like subslots on an algorithm that
> was not written with subslots in mind introduces a lot of inefficiency.

It's actually not bad, since all of the subslot rebuilds are triggered
in a single backtracking run. Anyway, I welcome having people work on
competing package managers, trying to do all of this stuff more
efficiently. :-)

> And it's not just subslots, newer features keep getting added to the
> dependency graph calculation and it gets slower and slower over time.
> It feels like revdep-rebuild moved into the dependency calculation!

I guess the main things that make it slower than it has been
historically would be things like --autounmask, --backtrack,
--complete-graph-if-new-use and --complete-graph-if-new-ver. Note that
you can use EMERGE_DEFAULT_OPTS to disable these things if you would
prefer to live without them. You might use something like --backtrack=2
if you want it to bail out early for all but the simplest backtracking
cases. Use --ignore-built-slot-operator-deps=y if you want to disable
all rebuilds involving subslots and slot-operators.
-- 
Thanks,
Zac