Re: [p2-dev] Resolver priority question

[Thomas Hallgren <thomas@xxxxxxx>]

Thanks. Much appreciated.

- thomas

On 2013-09-05 13:43, Daniel Le Berre wrote:
> The penalty for root IUs (explicitely installed IUs) or IUs to install is 1, the other penalties is a power of K
> (K for the most recent IU, K**2 for the second most recent IU, etc) where K is the number of installed IUs on the current system + 1.
>
> The relevant par of the code in p2 is here (line 73):
> http://git.eclipse.org/c/equinox/rt.equinox.p2.git/tree/bundles/org.eclipse.equinox.p2.director/src/org/eclipse/equinox/internal/p2/director/OptimizationFunction.java
>
> Daniel
>
> Le 5 sept. 2013 à 13:31, Thomas Hallgren <thomas@xxxxxxx> a écrit :
>
> > Hi Daniel,
> >
> > Thanks for an elaborate explanation. It all makes sense. Next question is of course, how is the magnitude of the two penalties (higher number of IU's versus older versions) determined?
> >
> > - thomas
> >
> > On 2013-09-05 10:48, Daniel Le Berre wrote:
> > > Hi Thomas,
> > >
> > > The resolver tries to install as few IUs as possible, because each installed IU is associated with a penalty.
> > >
> > > Furthermore, there is also another rule which will prefer most recent versions to older ones.
> > > It means that the penalty is smaller for most recent versions than for older versions.
> > >
> > > So it means that when you use the most recent IUs, solutions with fewer installed IUs will be preferred to solutions with a higher number of IUs.
> > >
> > > But since at the end we aggregate all penalties, there might be some compensation effects:
> > > a solution installing many new recent IUs may be preferred to a solution installing a few older IUs.
> > >
> > > Daniel
> > >
> > > Le 4 sept. 2013 à 19:23, Thomas Hallgren <thomas@xxxxxxx> a écrit :
> > >
> > > > Confronted with two OK solutions, what would the p2 resolver do if one solution was resolved by brining in a higher number of IUs? If it prefers the one with a lower IU count, what does it do if that one satisfies some requirements with lower versions?
> > > >
> > > > - thomas
> > > > _______________________________________________
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> > > --
> > >           Daniel Le Berre     mailto:leberre@xxxxxxx
> > >           MCF-HDR, CRIL-CNRS UMR 8188 Universite d'Artois
> > >           http://www.cril.univ-artois.fr/~leberre
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>          Daniel Le Berre     mailto:leberre@xxxxxxx
>          PR, CRIL-CNRS UMR 8188 Universite d'Artois
>          http://www.cril.univ-artois.fr/~leberre
>
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