On Tue, Jul 27, 2021 at 2:18 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Tue, 27 Jul 2021 09:31:33 -0700 Evan Green <evgreen@xxxxxxxxxxxx> wrote: > > > > 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. Patch withdrawn. -Evan
