Re: [RFC 0/3] Pin page control subsystem

[Benjamin LaHaise <bcrl@kvack.org>]

On Tue, Aug 13, 2013 at 11:46:42AM +0200, Krzysztof Kozlowski wrote:
> Hi Minchan,
> 
> On wto, 2013-08-13 at 16:04 +0900, Minchan Kim wrote:
> > patch 2 introduce pinpage control
> > subsystem. So, subsystems want to control pinpage should implement own
> > pinpage_xxx functions because each subsystem would have other character
> > so what kinds of data structure for managing pinpage information depends
> > on them. Otherwise, they can use general functions defined in pinpage
> > subsystem. patch 3 hacks migration.c so that migration is
> > aware of pinpage now and migrate them with pinpage subsystem.
> 
> I wonder why don't we use page->mapping and a_ops? Is there any
> disadvantage of such mapping/a_ops?

That's what the pending aio patches do, and I think this is a better 
approach for those use-cases that the technique works for.

The biggest problem I see with the pinpage approach is that it's based on a
single page at a time.  I'd venture a guess that many pinned pages are done 
in groups of pages, not single ones.

		-ben

> Best regards,
> Krzysztof

-- 
"Thought is the essence of where you are now."

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