Re: [PATCH v4] mm: Enable suspend-only swap spaces

[Pavel Machek]

Hi!

> > > > Pavel just mentioned uswsusp, and I wonder if it would be a possible
> > > > alternative to this patch.
> > >
> > > I think you're right that it would be possible to isolate the
> > > hibernate image with uswsusp if you avoid using the SNAPSHOT_*SWAP*
> > > ioctls. But I'd expect performance to suffer noticeably, since now
> > > every page is making a round trip out to usermode and back. I'd still
> > > very much use the HIBERNATE_ONLY flag if it were accepted, I think
> > > there's value to it.
> >
> > The uswsusp option makes your patch a performance optimization rather
> > than a feature-add.  And we do like to see quantitative testing results
> > when considering a performance optimization.  Especially when the
> > performance optimization is a bit icky, putting special-case testing
> > all over the place, maintenance cost, additional testing effort, etc.
> >
> > I do think that diligence demands that we quantify the difference.  Is
> > this a thing you can help with?
> 
> I'm wrong about the performance. Uswsusp is just as fast, and possibly
> faster in my use case than kernel-driven hibernate. What's more,
> uswsusp also helps me solve several additional problems I hadn't
> tackled yet that were looming in front of me. Thanks all for your
> patience and thoughtful review on this.

Great to see uswsusp being used :-).

Thanks,
								Pavel
-- 
http://www.livejournal.com/~pavelmachek

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