Message-Id: <1243297196.16743.137.camel@nigel-laptop>
Date:	Tue, 26 May 2009 10:19:56 +1000
From:	Nigel Cunningham <nigel@...onice.net>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-pm@...ts.linux-foundation.org,
	tuxonice-devel@...ts.tuxonice.net, linux-kernel@...r.kernel.org,
	Pavel Machek <pavel@....cz>
Subject: Re: [TuxOnIce-devel] [RFC] TuxOnIce

Hi.

On Tue, 2009-05-26 at 00:02 +0200, Rafael J. Wysocki wrote:
> On Monday 25 May 2009, Nigel Cunningham wrote:
> > On Sat, 2009-05-09 at 15:54 +0200, Pavel Machek wrote:
> > > > This is going to sound arrogant, but please don't take it that way: I
> > > > can't see any other way of putting it. I don't *think* my code is
> > > > better. It is better. swsusp has essentially stood still since Pavel
> > > > first forked the code and got it merged. Yes, you have done some
> > > > great
> > > 
> > > I don't think _I_ forked anything.
> > 
> > The conversation for May 2002 (around when you got it merged into
> > vanilla) is here:
> > 
> > https://sourceforge.net/mailarchive/forum.php?forum_name=swsusp-devel&max_rows=100&style=flat&viewmonth=200205
> > 
> > Not sure why Sourceforge wants you to log in to get at it.
> > 
> > > > work on improving the code too and yes, you've done your work on the
> > > > version that was already merged. But your changes been more in the area
> > > > of fixing/improving what's already there than adding new and useful
> > > > features. On the other side, I've continued to improve the code,
> > > 
> > > Yes, that's fair. We kept incremental fixing, improving. On the other
> > > hand, you added new features.
> > > 
> > > > new features (support for multiple swap partitions & files, for writing
> > > > to ordinary files, for mulithreaded I/O etc etc) making it more useful
> > > > and more reliable. There are some new features that have been put in
> > > > swsusp, but in just about every case (I think there might be an
> > > > exception or two), they're things TuxOnIce had for ages before. eg: SMP
> > > > support came with cpu hotplugging in 2.6.12 or so. TuxOnIce had SMP
> > > > support in 2.4.
> > > 
> > > You were moving faster because you did not have to move in small
> > > incremental steps, and you were allowed to add temporary hacks into
> > > the code. Is that surprising? Not to me.
> > 
> > No, I moved in small incremental steps too - and the odd big rework.
> > 
> > > [Please update http://www.tuxonice.net/features pages. They are
> > > misleading; yes, uswsusp supports threaded writes, can be reconfigured
> > > without rebooting and yes we did test failure paths, it can be
> > > scripted, and it supports checksums. I don't know what you mean by
> > > kexec support, but kexec/kjump could be used as whole another method
> > > of hibernating a machine, basically adding fourth row to your table.]
> > 
> > uswsusp supports multithreaded I/O? Wow. When did that happen?
> > 
> > Okay. How do you reconfigure it without rebooting (I mean tell it to
> > write the image to a different location)? (So I can put the instructions
> > on the page).
> > 
> > Regarding kexec, I'm thinking about making TuxOnice able to do a kexec
> > jump and then continue with writing the image (after preparing it in the
> > original kernel).
> > 
> > (Note to self for later - look above for other things Pavel says uswsusp
> > can do when updating the page).
> > 
> > > > > > I take a modular approach and you have everything hardwired.
> > > > > 
> > > > > That's because using modules woudn't really make sense for us. :-)
> > > > 
> > > > I'm not saying modules but modular. TuxOnIce has support for compression
> > > > neatly abstracted into one file, for swap in another and so on.
> > > > [u]swsusp doesn't.
> > > 
> > > uswsusp has compression neatly abstracted into userland. I still
> > > believe that's superior to kernel module.
> > 
> > Okay, but what about swap support? Modifying swsusp or uswsusp to write
> > to ordinary files would require a huge change in multiple places -
> 
> Not at all, it acutally works in uswsusp (I still hate this name) as is.
> 
> > where you store the image isn't currently abstracted at all from the issue of
> > what you're storing, and I dare say a person with a slow computer who
> > gets no advantage out of compression will have to recompile uswsusp to
> > turn it off (if that's allowed for).
> 
> Again, not at all, there's a configuration option allowing you to switch
> compression on/off (just like encryption, multithreaded I/O and a few other
> things).
> 
> But that's just for the record, because I'm really far away from saying that
> uswsusp (who gave this name to it?) is "the ultimate hibernation solution" for
> Linux.  In fact, I think it is suboptimal for a few good reasons and I'd like
> to improve Linux hibernation.  One way to achieve this goal is to join forces
> with your project.

Re the features, okay. I don't claim to have looked at your code
recently or in great detail when I did look at it.

Re the name, I think from memory that I had some input there - made a
joke or something - and Pavel took me seriously. Sorry!

Re joining forces, yes please. I have precious little time, too many
other commitments and would frankly be just as happy to chuck the whole
thing in - except that I want better hibernation than is in the kernel
at the moment and am not going to stop using Linux.

By the way, do you really have multithreaded I/O in uswsusp? If so, what
sort of throughput are you achieving combined with compression (please
also quote hdparm -t's speed of the swap partition for comparison).

Regards,

Nigel

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