Re: [RFC 2/3] vmscan hook

[Rik van Riel]

On 01/17/2012 07:18 PM, KAMEZAWA Hiroyuki wrote:
> On Wed, 18 Jan 2012 08:08:01 +0900
> Minchan Kim<minchan@xxxxxxxxxx>  wrote:
>
> > > > > 2. can't we measure page-in/page-out distance by recording something ?
> > > >
> > > > I can't understand your point. What's relation does it with swapout prevent?
> > >
> > > If distance between pageout ->  pagein is short, it means thrashing.
> > > For example, recoding the timestamp when the page(mapping, index) was
> > > paged-out, and check it at page-in.
> >
> > Our goal is prevent swapout. When we found thrashing, it's too late.
>
> If you want to prevent swap-out, don't swapon any. That's all.
> Then, you can check the number of FILE_CACHE and have threshold.

I think you are getting hung up on a word here.

As I understand it, the goal is to push out the point where
we start doing heavier swap IO, allowing us to overcommit
memory more heavily before things start really slowing down.

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