Re: [PATCH] mm: swsusp shrink_all_memory tweaks

[Con Kolivas <kernel@kolivas.org>]

On Saturday 25 March 2006 02:16, Rafael J. Wysocki wrote:
> On Friday 24 March 2006 08:07, Con Kolivas wrote:
> > On Tuesday 21 March 2006 05:46, Rafael J. Wysocki wrote:
> > > swsusp_shrink_memory() is still wrong, because it will always fail for
> > > image_size = 0.  My bad, sorry.
> > >
> > > The appended patch (on top of yours) should fix that (hope I did it
> > > right this time).
> >
> > Well I discovered that if all the necessary memory is freed in one call
> > to shrink_all_memory we don't get the nice updating printout from
> >  swsusp_shrink_memory telling us we're making progress. So instead of
> >  modifying the function to call shrink_all_memory with the full amount
> > (and since we've botched swsusp_shrink_memory a few times between us), we
> > should limit it to a max of SHRINK_BITEs instead.
> >
> >  This patch is fine standalone.
> >
> >  Rafael, Pavel what do you think of this one?
>
> In principle it looks good to me, but when I tested the previous one I
> noticed shrink_all_memory() tended to return 0 prematurely (ie. when it was
> possible to free some more pages).  It only happened if more than 50% of
> memory was occupied by application data.
>
> Unfortunately I couldn't find the reason.

Perhaps it was just trying to free up too much in one go. There are a number 
of steps a mapped page needs to go through before being finally swapped and 
there are a limited number of iterations over it. Limiting it to SHRINK_BITEs 
at a time will probably improve that.

Cheers,
Con