Re: Which is simpler? (Was Re: [Suspend2-devel] Re: [ 00/10] [Suspend2] Modules support.)

From: Rafael J. Wysocki
Date: Wed Feb 22 2006 - 18:43:48 EST


Hi,

On Wednesday 22 February 2006 23:24, Pavel Machek wrote:
> > > It is doable - I'm doing it now, but am thinking about reverting part of the
> > > code to use pbes again. If you're going to look at using bitmaps in place of
> > > pbes, me changing would be a waste of time. Do you want me to hold off for a
> > > while? (I'll happily do that, as I have far more than enough to keep me
> > > occupied at the moment anyway).
> >
> > Well, I'd say so. :-)
> >
> > Frankly, I didn't think of dropping PBEs right now, but in the long run
> > that's worth considering, IMO. The advantage of PBEs is that they are easy to
> > handle in the assembly parts, but apart from this they are a bit wasteful
> > (not very much, though).
>
> Of course it will depend on what patch looks like, but changing
> assembly parts is hard -- you have to change all the architectures,
> and better not make any mistake.

Yes, that would be a lot of work, so it's rather a long term "vision".
I think we should try to get the pagecache stuff right first anyway.

> > The fact that we use page flags to store some suspend/resume-related
> > information is a big disadvantage in my view, and I'd like to get rid of that
> > in the future. In principle we could use a bitmap, or rather two of them,
> > to store the same information independently of the page flags, and
> > if we use bitmaps for this purpose, we can use them also instead of
> > PBEs.
>
> Well, we "only" use 2 bits... :-).

In my view the problem is this adds constraints that other people have to take
into account. Not a good thing if avoidable IMHO.

Greetings,
Rafael

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