Re: [PATCH 5/6] PM/Hibernate: Do not release preallocated memory unnecessarily (rev. 2)

From: Rafael J. Wysocki
Date: Thu May 14 2009 - 13:53:30 EST


On Thursday 14 May 2009, Pavel Machek wrote:
> Hi!
>
> > Since the hibernation code is now going to use allocations of memory
> > to make enough room for the image, it can also use the page frames
> > allocated at this stage as image page frames. The low-level
> > hibernation code needs to be rearranged for this purpose, but it
> > allows us to avoid freeing a great number of pages and allocating
> > these same pages once again later, so it generally is worth doing.
> >
> > [rev. 2: Take highmem into account correctly.]
>
> I don't get it. What is advantage of this patch? It makes the code
> more complex... Is it supposed to be faster?

Yes, in some test cases it is reported to be faster (along with [4/6],
actually).

Besides, we'd like to get rid of shrink_all_memory() eventually and it is a
step in this direction.

Thanks,
Rafael
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