Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19

[Nick Piggin]

Martin J. Bligh wrote:
> > Ahh, you're right, there's a totally separate watermark for highmem.
> >
> > I think I even remember this. I may even be responsible. I know some of 
> > our less successful highmem balancing efforts in the 2.4.x timeframe had 
> > serious trouble when they ran out of highmem, and started pruning lowmem 
> > very very aggressively. Limiting the highmem water marks meant that it 
> > wouldn't do that very often.
> >
> > I think your patch may in fact be fine, but quite frankly, it needs 
> > testing under real load with highmem.

I'd prefer not. The reason is that it increases the "min"
watermark, which only gets used basically by GFP_ATOMIC and
PF_MEMALLOC allocators - neither of which are likely to want
highmem.

Also, I don't think anybody cares about higher order highmem
allocations. At least the patches in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113082256231168&w=2

Should be applied before this. However they also need more
testing so I'll be sending them to Andrew first.

Patch 2 does basically the same thing as your patch, without
increasing the min watermark.

--
SUSE Labs, Novell Inc.

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