Re: Is it possible to implement the per-node page cache for programs/libraries?

[Matthew Wilcox]

On Fri, Sep 03, 2021 at 05:10:31PM +1000, Nicholas Piggin wrote:
> Excerpts from Matthew Wilcox's message of September 2, 2021 8:17 pm:
> > On Thu, Sep 02, 2021 at 01:25:36PM +1000, Nicholas Piggin wrote:
> >> > I have been thinking about this a bit; one of our internal performance
> >> > teams flagged the potential performance win to me a few months ago.
> >> > I don't have a concrete design for text replication yet; there have been
> >> > various attempts over the years, but none were particularly compelling.
> >> 
> >> What was not compelling about it?
> > 
> > It wasn't merged, so clearly it wasn't compelling enough?
> 
> Ha ha. It sounded like you had some reasons you didn't find it 
> particularly compelling :P

I haven't studied it in detail, but it seems to me that your patch (from
2007!) chooses whether to store pages or pcache_desc pointers in i_pages.
Was there a reason you chose to do it that way instead of having per-node
i_mapping pointers?  (And which way would you choose to do it now, given
the infrastructure we have now?)