Re: [patch] VM stable again?

[Rik van Riel <riel@conectiva.com.br>]

On Mon, 15 May 2000, Ingo Molnar wrote:
> On Mon, 15 May 2000, Rik van Riel wrote:
> 
> > - keep track of whether some process is critically low on
> >   memory and needs to call try_to_free_pages()
> > - if another allocation starts while the other app is in
> >   try_to_free_pages(), free some memory ourselves
> > - (skip point 2 if there is enough free memory, but that's
> >   just a minor performance optimisation)
> 
> yep, this should work. A minor comment:
> 
> > +		if (atomic_read(&free_before_allocate))
> 
> i believe this needs to be per-zone and should preferably be
> read within the zone spinlock - not atomic operations. Updating
> a global counter is a big time problem on SMP.

It should be per-pgdat. Per-zone probably won't work since
having this counter per-zone may interfere with both fallback
and balancing between the zones.

regards,

Rik
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