Re: swsusp / suspend2 reliability (was Re: [Suspend2-devel] Re: Suspend2 - Request for review & inclusion in -mm)

Pavel Machek
2006-06-28T22:24:34Z

Hi!

> > Okay, can I get some details? Like how much memory does system have,
> > what stress test causes the failure?
>
> The machine has 1GB of RAM, filling it up beyond 500MB, maybe 600MB usually
> made swsusp a problem. I'd need to close apps then to be able to
> suspend.

I'm pretty sure I do suspending with most of RAM full. You have
big-enough swap partition, right?

> Using suspend2 fixes that for me. I can even decide how much memory I want
> suspended, the rest will be reliably discarded. I did a benchmark on two
> similar machines swsusp: would take 45 seconds until resume (that's about the
> same time it takes it to boot normally) suspend2 would take 25 seconds (and
> have warm caches as a bonus). Not having a progress indicator also doesn't
> really help.

Set console loglevel (see Doc*/power/swsusp.txt), and you should get
some progress. But yes, swsusp is slow; uswsusp should be about the
same speed as suspend2.

> Another thing I really like about suspend2 is that I can easily set it up so
> it goes into S3 after writing the image. It would resume much faster then,
> and in case it runs out of battery, I can still 'normally' resume from disk.
> That's incredibly useful, especially since not all devices are known to
> completely switch off during S3, and resuming from S3 is generally known to
> cause problems. I've yet to see suspend2 failing though.

> Is such a disk-backed hibernate also possible with (u)swsusp?

We call it s2both and yes, it is supported.
Pavel
--
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