suspend-to-disk

[C. Scott Ananian]

On 7/8/07, Mitch Bradley <wmb at laptop.org> wrote:
> It wouldn't be necessary to save read-only code ("text" pages) to the
> save area; just mark those pages "not present" and save the information
> necessary to page them back in.  But that would probably make the resume
> slower, because of the JFFS2 operations necessary to resolve all those
> page-in references.  The firmware part of the resume would be faster,
> but the overall suspend/resume process might take longer (or maybe not;
> you trade not having to write the data out on the way down for having to
> do more work on the way up).

The existing linux suspend-to-disk does this: pages that are
disk-backed are not duplicated, and dirty pages are written out rather
than saved dirty.  There is a time penalty for doing this.  Suspend2
has support for page compression as well (http://www.tuxonice.net/)
and seems to be fairly mature and under active development, although
I've only used the stock kernel STD myself.  But it would make sense
to use the existing suspend2 stuff instead of rolling our own in OFW.
I've already volunteered in #olpc to write the early userspace
support, since I seem to have adopted the initramfs (and since I wrote
the STD stuff in yaird).
 --scott

-- 
                         ( http://cscott.net/ )