Re: [RFT][PATCH] mm: drop behind

[Peter Zijlstra <peterz@infradead.org>]

Hi Tim,

On Wed, 2007-07-11 at 15:37 -0700, Tim Pepper wrote:
> On 7/9/07, Peter Zijlstra <peterz@infradead.org> wrote:
> > Use the read-ahead code to provide hints to page reclaim.
> >
> > This patch has the potential to solve the streaming-IO trashes my
> > desktop problem.
> >
> > It tries to aggressively reclaim pages that were loaded in a strong
> > sequential pattern and have been consumed. Thereby limiting the damage
> > to the current resident set.
> 
> Interesting...
> 
> Would it make sense to tie this into (finally) making
> POSIX_FADV_NOREUSE something more than a noop?

We talked about that, but the thing is, if we make the functionality
conditional, nobody will ever use it :-/

So, yes, in a perfect world that would indeed make sense. However since
nobody ever uses these [fm]advise calls,..

So the big question is, does this functionally hurt any workload? If it
turns out it does (which I still doubt) then we might hide it behind
knobs, otherwise I'd like to keep it always on.

Peter



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