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

[Nigel Cunningham]

Hi Rafael.

On Wednesday 22 February 2006 06:40, Rafael J. Wysocki wrote:
> On Tuesday 21 February 2006 05:19, Dmitry Torokhov wrote:
> > On Monday 20 February 2006 21:57, Nigel Cunningham wrote:
> > > For the record, my thinking went: swsusp uses n (12?) bytes of meta
> > > data for every page you save, where as using bitmaps makes that much
> > > closer to a constant value (a small variable amount for recording where
> > > the image will be stored in extents). 12 bytes per page is 3MB/1GB. If
> > > swsusp was to add support for multiple swap partitions or writing to
> > > files, those requirements might be closer to 5MB/GB.
> >
> > 5MB/GB amounts to 0.5% overhead, I don't think you should be concerned
> > here. Much more important IMHO is that IIRC swsusp requires to be able to
> > free 1/2 of the physical memory whuch is hard on low memory boxes.
>
> I see another point in using bitmaps: we could avoid modifying page flags
> and use bitmaps to store all of the temporary information.  I thought about
> it for some time and I think it's doable.

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).

Regards,

Nigel

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