Re: [PATCH] emulate accessed bit for EPT

[Marcelo Tosatti]

On Thu, Feb 04, 2010 at 06:47:15PM +0100, Andrea Arcangeli wrote:
> On Thu, Feb 04, 2010 at 08:40:43AM -0500, Rik van Riel wrote:
> > I suspect it won't be very many. I have been monitoring
> > /proc/meminfo on my system while testing this patch, and
> > it is quite typical that the size of the inactive anon
> > list does not change for minutes at a time.
> > 
> > In other words, no pages are moved onto or off of the
> > inactive anon list for several minutes. That corresponds
> > to a very small number of minor faults introduced by my
> > patch.
> 
> When there's light VM pressure, ideally there should be zero overhead
> caused by the patch. When there is VM pressure this will avoid some
> unnecessary I/O which should outweight the minor faults. It should be
> a good default behavior.

Agree.

But perhaps a module parameter to turn accessed bit emulation off might
be handy in the future?

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