Re: [PATCH 0/3] swsusp: shrink file cache first

Re: [PATCH 0/3] swsusp: shrink file cache first

[Rafael J. Wysocki]

> Hello!

Hi Hannes,
 
> here are three patches that adjust the memory shrinking code used for
> suspend-to-disk.
> 
> The first two patches are cleanups only and can probably go in
> regardless of the third one.
> 
> The third patch changes the shrink_all_memory() logic to drop the file
> cache first before touching any mapped files and only then goes for
> anon pages.
> 
> The reason is that everything not shrunk before suspension has to go
> into the image and will be 'prefaulted' before the processes can
> resume and the system is usable again, so the image should be small
> and contain only pages that are likely to be used right after resume
> again.  And this in turn means that the inactive file cache is the
> best point to start decimating used memory.
> 
> Also, right now, subsequent faults of contiguously mapped files are
> likely to perform better than swapin (see
> http://kernelnewbies.org/KernelProjects/SwapoutClustering), so not
> only file cache is preferred over other pages, but file pages over
> anon pages in general.
> 
> Testing up to this point shows that the patch does what is intended,
> shrinking file cache in favor of anon pages.  But whether the idea is
> correct to begin with is a bit hard to quantify and I am still working
> on it, so RFC only.

Thanks a lot for the patches, I'll review them as soon as I can.

I've got them with broken headers, but that's not a big deal.

Best,
Rafael

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