Date:	Mon, 12 Feb 2007 10:45:09 +1100
From:	Nigel Cunningham <nigel@...el.suspend2.net>
To:	Willy Tarreau <w@....eu>
Cc:	Robert Hancock <hancockr@...w.ca>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: NAK new drivers without proper power management?

Hi.

On Mon, 2007-02-12 at 00:38 +0100, Willy Tarreau wrote:
> On Mon, Feb 12, 2007 at 10:18:42AM +1100, Nigel Cunningham wrote:
> [snip]
> > > Hmm sorry, but we don't have the same usages of notebooks. For no reason
> > > would I keep documents open, for two reasons :
> > > 
> > >   - when I shutdown my notebook, it is to move from one customer to
> > >     home/company/another customer. There's no related work anyway, the
> > >     network will have changed and I'll have to switch nearly all of my
> > >     apps anyway. So using suspend just to save one reboot is not worth
> > >     it (for me) IMHO.
> > 
> > The network configuration utilities can help there. In addition,
> > Suspend2 preserves the commandline you used to boot with
> > (/sys/power/suspend2/resume_commandline), so you can use a combination
> > of slightly varying grub entries (I have one for not starting ath0 and
> > one for starting it) and scripts to do different things in different
> > environments. The resume_commandline is writable, so can be cleared
> > after usage if there were anything sensitive there.
> 
> OK, I see there are features to make life easier when I decide to use
> suspend. But it looks like that using suspend is the goal and dealing
> with the constraints is a lot of work and I'm still far from being
> convinced that it would provide me advantage.

Ok. I don't feel like I have to convince everyone :)

> > >   - I would certainly not keep open documents that are on crypted FS
> > >     while I travel. Otherwise, it would be a total waste of time to
> > >     enter my passphrase everytime I need to access them ! Some might
> > >     argue that it would save me a lot of time, providing me with the
> > >     ability to type my passphrase only once a month, but that's not
> > >     what I'm looking for :-)
> > 
> > People are using Suspend2 with encryption today (I'm not sure about
> > uswsusp). Some of them have set things up so you need to use a
> > passphrase or usb key to resume, and the image itself is of course
> > encrypted too.
> 
> Unless I'm mistaken, I have to type the passphrase twice then :
>   - once at suspend
>   - once at resume
> 
> which is once more per "boot" than what I'm doing on loop-aes.

I'm not sure. I don't use encryption myself, so I don't understand all
the fine details. I just know that there are people out there using
encryption, loop-aes, dmsetup and all that sort of stuff. I don't have
to worry about it because they use an initrd/ramfs to do whatever they
need to do to provide access to the device on which the image is found,
then

echo /dev/whatever_funny_device > /sys/power/suspend2/resume2
echo > /sys/power/suspend2/do_resume

> > You could also close the document and not the app. Or both and just get
> > the benefit of having the app in page cache post-resume.
> 
> I'm not much convinced by the advantage of reading 500 MB on disk to have
> emacs in hot cache :-)

Neither am I! Presumably you'd have a lot more than emacs in there
though :) You could always switch to vim! (*ducks*)

Regards,

Nigel

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