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Date: Wed, 25 Apr 2007 18:43:45 -0400
From: Chuck Ebbert <cebbert@redhat.com>
Organization: Red Hat
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To: Linus Torvalds <torvalds@linux-foundation.org>
CC: Pavel Machek <pavel@ucw.cz>, Kenneth Crudup <kenny@panix.com>,
       Nick Piggin <npiggin@suse.de>, Mike Galbraith <efault@gmx.de>,
       linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
       Con Kolivas <kernel@kolivas.org>, suspend2-devel@lists.suspend2.net,
       Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>,
       Arjan van de Ven <arjan@infradead.org>
Subject: Re: suspend2 merge (was Re: [Suspend2-devel] Re: CFS and suspend2:
 hang in atomic copy)
References: <20070419070437.GA25211@elte.hu> <20070424202336.GC16503@elf.ucw.cz> <alpine.LFD.0.98.0704241327180.9964@woody.linux-foundation.org> <20070424212408.GD16457@elf.ucw.cz> <alpine.LFD.0.98.0704241630170.9964@woody.linux-foundation.org> <20070425072350.GA6866@ucw.cz> <Pine.LNX.4.64.0704251239110.8406@vaio.localdomain> <alpine.LFD.0.98.0704251252070.9964@woody.linux-foundation.org> <20070425202741.GC17387@elf.ucw.cz> <alpine.LFD.0.98.0704251332090.9964@woody.linux-foundation.org> <20070425214420.GG17387@elf.ucw.cz> <alpine.LFD.0.98.0704251515140.9964@woody.linux-foundation.org>
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Linus Torvalds wrote:
> 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.
> 

Freeze is a subset of suspend, isn't it? (It might be an empty subset
in some cases.)