From: Nigel Cunningham <nigel@suspend2.net>
Organization: Suspend2.net
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: Which is simpler? (Was Re: [Suspend2-devel] Re: [ 00/10] [Suspend2] Modules support.)
Date: Fri, 10 Feb 2006 08:16:13 +1000
User-Agent: KMail/1.9.1
Cc: Pavel Machek <pavel@ucw.cz>, suspend2-devel@lists.suspend2.net,
       Lee Revell <rlrevell@joe-job.com>, linux-kernel@vger.kernel.org
References: <20060201113710.6320.68289.stgit@localhost.localdomain> <20060209092555.GB2940@elf.ucw.cz> <200602091422.40738.rjw@sisk.pl>
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Hi.

On Thursday 09 February 2006 23:22, Rafael J. Wysocki wrote:
> > > I've begun briefly to have a look at this.
> > >
> > > Part of the problem I have, both with doing incremental patches for
> > > swsusp and with doing a userspace version, is that some of the
> > > fundamentals are redesigned in suspend2. The most important of these =
is
> > > that we store the metadata in bitmaps (for pageflags) and extents (for
> > > storage) instead of pbes. Do you have thoughts on how to overcome that
> > > issue? Are you willing, for example, to do work on switching swsusp to
> > > use a different method of storing its data?
> >
> > Any changes to userspace are a fair game. OTOH kernel provides linear
> > image to be saved to userspace, and what it uses internally should not
> > be important to userland parts. (And Rafael did some changes in that
> > area to make it more effective, IIRC).
>
> Yes.  The code is now split into the part that handles the snapshot image
> (in snapshot.c) and the part that writes/reads it to swap (in swap.c). [I=
'm
> referring to recent -mm kernels.]
>
> The access to the snapshot image is provided via the functions
> snapshot_write_next() and snapshot_read_next() that are called by the
> code in swap.c and may be used by the user space tools via the
> interface in user.c.  In principle it ought to be possible to plug
> something else instead of the code in snapshot.c without
> breaking the rest.

So, what is the answer then? If I submitted patches to provide the possibil=
ity=20
of separating LRU pages into a separate stream of pages to be read/written,=
=20
would it have any chance of getting merged? (Along with other patches to ma=
ke=20
writing a full image of memory possible).

Regards,

Nigel
=2D-=20
See our web page for Howtos, FAQs, the Wiki and mailing list info.
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