Re: [PATCH] docs/vm: add documentation of memory models

Mike Rapoport
2019-04-25T08:22:50Z

Hi Randy,

On Wed, Apr 24, 2019 at 06:08:46PM -0700, Randy Dunlap wrote:
> On 4/24/19 3:28 AM, Mike Rapoport wrote:
> > Describe what {FLAT,DISCONTIG,SPARSE}MEM are and how they manage to
> > maintain pfn <-> struct page correspondence.
> >
> > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> > ---
> > Documentation/vm/index.rst | 1 +
> > Documentation/vm/memory-model.rst | 171 ++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 172 insertions(+)
> > create mode 100644 Documentation/vm/memory-model.rst
> >
>
> Hi Mike,
> I have a few minor edits below...

I kinda expected those ;-)

> > diff --git a/Documentation/vm/memory-model.rst b/Documentation/vm/memory-model.rst
> > new file mode 100644
> > index 0000000..914c52a
> > --- /dev/null
> > +++ b/Documentation/vm/memory-model.rst

...

> > +
> > +With FLATMEM, the conversion between a PFN and the `struct page` is
> > +straightforward: `PFN - ARCH_PFN_OFFSET` is an index to the
> > +`mem_map` array.
> > +
> > +The `ARCH_PFN_OFFSET` defines the first page frame number for
> > +systems that their physical memory does not start at 0.
>
> s/that/when/ ? Seems awkward as is.

Yeah, it is awkward. How about

The `ARCH_PFN_OFFSET` defines the first page frame number for
systems with physical memory starting at address different from 0.

> > +
> > +DISCONTIGMEM
> > +============
> > +
>
> thanks.
> --
> ~Randy
>

--
Sincerely yours,
Mike.