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

From: Rafael J. Wysocki
Date: Tue Feb 21 2006 - 15:38:18 EST


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.

Greetings,
Rafael
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