Re: [PATCH] shrinker support for the mmu cache

[Marcelo Tosatti <marcelo@kvack.org>]

On Sun, Mar 16, 2008 at 01:28:43PM +0200, Avi Kivity wrote:
> Marcelo Tosatti wrote:
> > On Wed, Mar 12, 2008 at 08:13:41PM +0200, Izik Eidus wrote:
> >   
> >> this patch simply register the mmu cache with the shrinker.
> >>     
> >
> > Hi Izik,
> >
> > Nice.
> >
> > I think you want some sort of aging mechanism here. Walk through all
> > translations of a shadow page clearing the referenced bit of all
> > mappings it holds (and moving pages with any accessed translation to the
> > head of the list).
> >   
> 
> While aging is not too hard to do, I don't think it would add much in 
> practice; we rarely observe mmu shadow pages being recycled due to 
> memory pressure.  So this is mostly helpful for preventing a VM from 
> pinning memory when under severe memory pressure, where we don't expect 
> good performance anyway.

Issue is that the shrinker callback will not be called only under
severe memory pressure, but for normal system pressure too.


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