Re: kswapd @ 60-80% CPU during heavy HD i/o.

[Roger Larsson <roger.larsson@norran.net>]

Rik van Riel wrote:
> 
> On Tue, 2 May 2000, Roger Larsson wrote:
> 
> > I have been playing with the idea to have a lru for each zone.
> > It should be trivial to do since page contains a pointer to zone.
> >
> > With this change you will shrink_mmap only check among relevant pages.
> > (the caller will need to call shrink_mmap for other zone if call failed)
> 
> That's a very bad idea.

Has it been tested?
I think the problem with searching for a DMA page among lots and lots
of normal and high pages might be worse...

> 
> In this case you can end up constantly cycling through the pages of
> one zone while the pages in another zone remain idle.

Yes you might. But concidering the possible no of pages in each zone,
it might not be that a bad idea.

You usually needs normal pages and there are more normal pages.
You rarely needs DMA pages but there are less.
=> recycle rate might be about the same...

Anyway I think it is up to the caller of shrink_mmap to be intelligent
about which zone it requests.

> 
> Local page replacement is worse than global page replacement and
> has always been...
> 
> regards,
> 
> Rik
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