Re: ~500 megs cached yet 2.6.5 goes into swap hell

[Marc Singer]

On Thu, Apr 29, 2004 at 01:48:02PM +1000, Nick Piggin wrote:
> Marc Singer wrote:
> >On Thu, Apr 29, 2004 at 10:21:24AM +1000, Nick Piggin wrote:
> >
> >>Anyway, I have a small set of VM patches which attempt to improve
> >>this sort of behaviour if anyone is brave enough to try them.
> >>Against -mm kernels only I'm afraid (the objrmap work causes some
> >>porting difficulty).
> >
> >
> >Is this the same patch you wanted me to try?  
> >
> >  Remember, the embedded system where NFS IO was pushing my
> >  application out of memory.  Setting swappiness to zero was a
> >  temporary fix.
> >
> >
> 
> Yes this is the same patch I wanted you to try. Yes I
> remember your problem!
> 
> Didn't anyone come up with a patch for you to test the
> stale PTE theory? If so, what where the results?

Russell King is working on a lot of things for the MMU code in ARM.
I'm waiting to see where he ends up.  I believe he's planning on
removing the lazy PTE release logic.

I hacked at it for some time.  And I'm convinced that I correctly
forced the TLBs to be flushed.  Still, I was never able to get the
system to behave.

Now, I just read a comment you or WLI made about the page cache
use-once logic.  I wonder if that's the real culprit?  As I wrote to
Andrew Morton, the kernel seems to be assigning an awful lot of value
to page cache pages that are used once (or twice?).  I know that it
would be expensive to perform an HTG aging algorithm where the head of
the LRU list is really LRU.  Does your patch pursue this line of
thought?

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