linux-kernel - Re: [PATCH 1/1] x86: fix text

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Message-ID: <alpine.LFD.1.10.0804251024400.2779@woody.linux-foundation.org>
Date:	Fri, 25 Apr 2008 10:29:36 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Andi Kleen <andi@...stfloor.org>
cc:	Ingo Molnar <mingo@...e.hu>, Jiri Slaby <jirislaby@...il.com>,
	David Miller <davem@...emloft.net>, zdenek.kabelac@...il.com,
	rjw@...k.pl, paulmck@...ux.vnet.ibm.com, akpm@...ux-foundation.org,
	linux-ext4@...r.kernel.org, herbert@...dor.apana.org.au,
	penberg@...helsinki.fi, clameter@....com,
	linux-kernel@...r.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	pageexec@...email.hu, "H. Peter Anvin" <hpa@...or.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>
Subject: Re: [PATCH 1/1] x86: fix text_poke

On Fri, 25 Apr 2008, Andi Kleen wrote:
> 
> For suspend/resume we can actually just disable all the text_poke()s.
> They are not needed because we don't expect to stay in single CPU
> mode for long after wake up and they will just be undone again.

I do agree that we might decide to just not do this at all except for the 
actual physical bootup phase (which can use early_text_poke()). There may 
not be a whole lot of point to ever play with smp_alterinatives() at any 
other time.

> I guess if it really was a problem (but really I haven't heard about it)
> the easiest fix would be to just extended system_state to SYSTEM_SUSPEND
> and then skip them if that is true. 

Our device suspend right now takes about 3.5 seconds (that's using the 
debug thing, which adds a 5-second timeout). That *is* a problem, but it's 
historically been hidden by the fact that people are happy that suspend 
works at all when it does. 

These days, we're getting to the point (I think) that a lot more people 
are going to take suspend for granted. And I'd actually like to use it as 
a sleep state for desktop like usage (let's face it, when the screen goes 
dark, the CPU should just go into suspend too if it's used as a desktop by 
non-technical users).

And for that to be useful, it needs to come up quickly. Not add another 
second on top of the already-irritating delay of the screen waking up.

Are we there yet? Hell no. But I don't think we're too far off.

			Linus
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