Re: [PATCH][3/3] mm: swsusp post resume aggressive swap prefetch

[kernel@kolivas.org]

Quoting "Rafael J. Wysocki" <rjw@sisk.pl>:
> Sorry, I was wrong.  After resume the image pages in the swap are visible as
> free, because we allocate them after we have created the image (ie. the
> image
> contains the system state in which these pages are free).
> 
> Well, this means I really don't know what happens and what causes the
> slowdown.  It certainly is related to the aggressive prefetch hook in
> swsusp_suspend().  [It seems to search the whole swap, but it doesn't
> actually prefetch anything.  Strange.]

Are you looking at swap still in use? Swap prefetch keeps a copy of prefetched
pages on backing store as well as in ram so the swap space will not be freed on
prefetching. 

> > If so, is there a way to differentiate the two so we only aggressively
> > prefetch on kernel resume - is that what you meant by doing it in the
> > other file? 
> 
> Basically, yes.  swsusp.c and snapshot.c contain common functions,
> disk.c and swap.c contain the code used by the built-in swsusp only,
> and user.c contains the userland interface.  If you want something to
> be run by the built-in swsusp only, place it in disk.c.
> 
> Still in this particular case it won't matter, I'm afraid.

I don't understand what you mean by it won't matter?

Cheers,
Con

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