Re: [RFC] Removing page->flags

[Marcelo Tosatti <marcelo.tosatti@cyclades.com>]

On Thu, Feb 09, 2006 at 04:37:40PM +1100, Nick Piggin wrote:
> Magnus Damm wrote:
> 
> >But introducing a second page->flags is out of the question, and
> >breaking out flags and placing a pointer to them in the node data
> >structure will introduce more cache misses. So it is probably not
> >worth it.
> >
> 
> Yep. Even then, you can't simply have a single non-atomic flags word,
> unless _all_ flags are protected by the same lock.
> 
> >>
> >>It seems pretty unlikely that we'll get a pluggable replacement
> >>policy in mainline any time soon though.
> >
> >
> >So, do you think it is more likely that a ClockPro implementation will
> >be accepted then? Or is Linux "doomed" to LRU forever?
> >
> 
> I think (hope) that Linux eventually (if slowly) moves toward the best
> implementation available. I just don't think there will be sufficient
> justification for a pluggable page reclaim infrastructure in the mainline
> kernel.

Hi Nick,

There is no such thing as "best implementation available" given that
page replacement policy is nothing more than a set of heuristics
assuming certain characteristics of the underlying workload, and
optimizing for that.

Please refer to 
http://programming.kicks-ass.net/kernel-patches/clockpro-2/dev/2.6.16-rc2-1/

Peter's patchset implements a pluggable page reclaim infrastructure
which is used by CLOCK-Pro and CART. 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>