Re: subobj-rmap

[Davide Libenzi]

On Sun, 6 Apr 2003, Rik van Riel wrote:

> On Sun, 6 Apr 2003, Martin J. Bligh wrote:
>
> > Supposing we keep a list of areas (hung from the address_space) that
> > describes independant linear ranges of memory that have the same set
> > of vma's mapping them (call those subobjects). Each subobject has a
> > chain of vma's from it that are mapping that subobject.
> >
> > address_space ---> subobject ---> subobject ---> subobject ---> subobject
> >                        |              |              |              |
> >                        v              v              v              v
> >                       vma            vma            vma            vma
> >                        |                             |              |
> >                        v                             v              v
> >                       vma                           vma            vma
> >                        |                             |
> >                        v                             v
> >                       vma                           vma
>
> OK, lets say we have a file of 1000 pages, or
> offsets 0 to 999, with the following mappings:
>
> VMA A:   0-999
> VMA B:   0-200
> VMA C: 150-400
> VMA D: 300-500
> VMA E: 300-500
> VMA F:   0-999
>
> How would you describe these with independant
> regions ?

You should decompose each VMA in a set on independent regions. Immagine to
pile up each VMA with boundaries that cuts each other VMA address space :

1) |----------------------|
2)     |-----------|
3) |--------------------------|
4)         |-----------|

R) |---|---|-------|---|--|---|

    1   1   1       1   1  3
    3   2   2       3   3
        3   3       4
            4

- Davide