Re: [RFC] kernel facilities for cache prefetching

[Wu Fengguang]

On Tue, May 02, 2006 at 06:07:53PM +0200, Diego Calleja wrote:
> > Nope. mincore() only provides info about files that are currently
> > opened, by the process itself. The majority in the file cache are
> > closed files.
> 
> Yes; what I meant was:
> - start listening the process event connector as firsk task on startup
> - get a list of what files are being used (every second or something)
>   by looking at /proc/$PID/* stuff
> - mincore() all those files at the end of the bootup
> 
> > Yes, it can still be useful after booting :) One can get the cache
> > footprint of any task started at any time by taking snapshots of the
> > cache before and after the task, and do a set-subtract on them.
> 
> Although this certainly looks simpler for userspace (and complete, if
> you want to get absolutely all the info about files that get opened and
> closed faster than the profile interval of a prefetcher) 

Thanks, so it's a question of simplicity/completeness :)

> (another useful tool would be a dtrace-like thing)

Lubos Lunak also reminds me of SUSE's preload
(http://en.opensuse.org/index.php?title=SUPER_preloading_internals)
which is a user-land solution using strace to collect the info.

And there's Andrea Arcangeli's "bootcache userspace logging" kernel
patch(http://lkml.org/lkml/2004/8/6/216).

Wu
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