Re: [PATCH v2 2/4] mm: introduce fincore()

[Cédric Villemain]

Le vendredi 4 juillet 2014 03:12:30 Christoph Hellwig a écrit :
> On Thu, Jul 03, 2014 at 05:52:13PM -0400, Naoya Horiguchi wrote:
> > This patch provides a new system call fincore(2), which provides
> > mincore()- like information, i.e. page residency of a given file.
> > But unlike mincore(), fincore() has a mode flag which allows us to
> > extract detailed information about page cache like pfn and page
> > flag. This kind of information is very helpful, for example when
> > applications want to know the file cache status to control the IO
> > on their own way.
> 
> It's still a nasty multiplexer for multiple different reporting
> formats in a single system call.  How about your really just do a
> fincore that mirrors mincore instead of piggybacking exports of
> various internal flags (tags and page flags onto it.

The fincore à la mincore got some arguments against it too. It seems this 
implementations try (I've not tested nor have a close look yet) to 
answer both concerns : have details and also possible to have 
aggregation function not too expansive.

-- 
Cédric Villemain +33 (0)6 20 30 22 52
http://2ndQuadrant.fr/
PostgreSQL: Support 24x7 - Développement, Expertise et Formation

Attachment: signature.asc
Description: This is a digitally signed message part.