Re: suspend2 merge (was Re: [Suspend2-devel] Re: CFS and suspend2: hang in atomic copy)

[Linus Torvalds <torvalds@linux-foundation.org>]

On Thu, 26 Apr 2007, Pavel Machek wrote:
> 
> Suspend syncs caches/spins down. Freeze does not do anything.
> 
> That's okay, I keep claiming "freeze" is subset of "suspend". Can you
> name device where that is not true?

Sure. Like just about any PCI device that doesn't do things on its own.

A "freeze" does nothing at all, or perhaps shuts down the reader side 
(for something like a network controller).

A "suspend" does "write D3 to the suspend register". Absolutely zero in 
common.

> Remember we do
> 
> suspend(PMSG_FREEZE)
> atomic snapshot
> resume()
> write snapshot.

AND THAT IS STUPID. It mixes up "suspend()" and creating a snapshot in 
ways that are totally idiotic. There is nothing in common!

		Linus
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