Re: suspend2 merge (was Re: [Suspend2-devel] Re: CFS and suspend2:hang in atomic copy)
From: Linus Torvalds
Date: Wed Apr 25 2007 - 18:19:34 EST
On Wed, 25 Apr 2007, Pavel Machek wrote:
> Not the same... but they are still related. "freeze" (for atomic
> snapshot) is actually subset of "suspend"... freeze needs DMAs off and
> saved state, and you need DMAs off and saved state for "suspend".
THEY HAVE ABSOLUTELY NOTHING IN COMMON!
Nobody in their right mind thinks that "disable DMA" and "suspend" are
> So it is actually correct to do "suspend" when you want "freeze"; it
> is just slow. That's why they only differ in parameter these days.
It is *not* correct to "suspend" when you want "freeze".
I don't understand how you can even *claim* something like that.
Here's a trivial example:
- SCSI disk
Tell me, what does "suspend" do, and what does "freeze" (snapshot) do?
And name *one* thing that have in common.
I'll tell you: Nada. Zero. Zilch. Nothing.
"Freeze" for a disk is a total no-op. There is no DMA, there is no
nothing. In contrast, "suspend" for a disk is a totally valid operation.
Anybody who claims that these two operations are "related" is a moron.
I'm sorry Pavel, but that's exactly how it is.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/