Re: [PATCH] 2.6.4-rc2-mm1: vm-split-active-lists

[Nick Piggin]

Andrew Morton wrote:

> Nick Piggin <piggin@xxxxxxxxxxxxxxx> wrote:
>
> > Hmm... I guess it is still smooth because it is swapping out only
> > inactive pages. If the standard VM isn't being pushed very hard it
> > doesn't scan mapped pages at all which is why it isn't swapping.
> >
> > I have a preference for allowing it to scan some mapped pages though.
>
> I haven't looked at the code but if, as I assume, it is always scanning
> mapped pages, although at a reduced rate then the effect will be the same
> as setting swappiness to 100, except it will take longer.

Yep

> That effect is to cause the whole world to be swapped out when people
> return to their machines in the morning.  Once they're swapped back in the
> first thing they do it send bitchy emails to you know who.
>
> > From a performance perspective it's the right thing to do, but nobody likes
> it.

Yeah. I wonder if there is a way to be smarter about dropping these
used once pages without putting pressure on more permanent pages...
I guess all heuristics will fall down somewhere or other.

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