Re: OOM fixes 2/5

[Nick Piggin]

On Thu, 2005-01-20 at 22:20 -0800, Andrew Morton wrote:
> Andrea Arcangeli <andrea@xxxxxxx> wrote:
> >
> >  This is the forward port to 2.6 of the lowmem_reserved algorithm I
> >  invented in 2.4.1*, merged in 2.4.2x already and needed to fix workloads
> >  like google (especially without swap) on x86 with >1G of ram, but it's
> >  needed in all sort of workloads with lots of ram on x86, it's also
> >  needed on x86-64 for dma allocations. This brings 2.6 in sync with
> >  latest 2.4.2x.
> 
> But this patch doesn't change anything at all in the page allocation path
> apart from renaming lots of things, does it?
> 
> AFAICT all it does is to change the default values in the protection map. 
> It does it via a simplification, which is nice, but I can't see how it
> fixes anything.
> 
> Confused.


It does turn on lowmem protection by default. We never reached
an agreement about doing this though, but Andrea has shown that
it fixes trivial OOM cases.

I think it should be turned on by default. I can't recall what
your reservations were...?



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