Software suspend: and then there were two

Posted Jul 24, 2004 22:17 UTC (Sat) by Duncan (guest, #6647) [Link]

From the coverage, it looks to me like the
two current mainline
implementations will merge first, since that code is already cooked and
the patches ready to integrate. That would also bring an immediate
benefit in the form of simplification of the current two implementations
into one, lessening code bloat and simplifying the task of later
integration of swsuspend2.

Of course, that's all in how I read the LWN coverage. I could be reading
it wrong.

As for swsuspend2, I read that its the only one that does SMP, which
interests me since I've a dual Opteron system here as my desktop. (Yes,
it's fast! I've put that speed to good use running Gentoo, stage-one
compiled from source, and just freshly updated to KDE 3.3.0-beta2 today.
=:^) It'd be nice to be able to reliably suspend it and shut the fans and
the like off, since it's in my bedroom, and it IS a dual Opteron, with all
the cooling requirements that means. <g>

I recently discovered, to my GREAT surprise, that hardware suspend to RAM
seems to work on this system -- with one caveat -- upon recovery, my time
is all screwed up, as it doesn't advance with the hwclock over suspend and
naturally the software time doesn't advance either. The /real/
complicating factor there is that I've been running NTP, and it
would /really/ skew its compensation factor if it tried to do a time sync
in /that/ state!

Anyway, now that I know hardware suspend to RAM /can/ work, when I get
time, I'm hoping to throw an NTP service shutdown script into the suspend
sequence, and an NTPClient fast-sync script into the resume, b4 restarting
the NTP service itself.

That said, I'd STILL like to be able to suspend to disk, and be able to
entirely power off the system, and swsuspend2 seems my only chance at
that, at this point, tho I've been hesitant to look into it as it'd be my
first off-main patch, and I generally catch all the full releases and part
of the rcs, and an out-of-tree patch would mean either slowing down on
that, or potentially large amounts of work to keep it merged, particularly
given the rumored intrusiveness of the patch. I'd be /very/ happy to see
it merged into mainline, however, /particularly/ if it works for my dual
Opteron!

Duncan

Posted Jul 26, 2004 8:10 UTC (Mon) by NCunningham (guest, #6457) [Link]

Hi.

Duncan's reply is right. The two in-kernel versions are being merged first. There are already patches in the -mm tree.

After the dust has settled, I'll push my patches.

Right now I'm preparing the last feature changes to suspend2 before merging: adding support for resuming an initrd and making suspend modular. This will allow encrypted storage of an image (the encryption can be set up from the initrd), and will also allow at least some upgrades to suspend to be done without rebooting the system. The system I'm running right now has LZF, GZIP and swapwriter support compiled as modules. I just need to get the core done.

Regards,

Nigel