Re: [Lse-tech] [PATCH] Nonlinear kernel virtual to physical mapping

[Daniel P. <phi...@bo...>]

On April 11, 2002 11:46 pm, Kanoj Sarcar wrote:
> > You mean your incarnation of disconfigmem has no
> > changes in the 
> > alloc_pages path, right?  Because the incumbent
> > version adds _alloc_pages,
> > which is a major change, and a broken one at that,
> > since round robin
> > allocation makes no sense in the context of non-numa
> > discontigmem usage.
> > 
> 
> It depends ... if you can round robin allocations,
> you might be able to prevent any single chunk from
> going below the low water mark that triggers page
> reclamation, simply because pages get freed up after
> a while. 

You might not hurt too badly if the discontig chunks are not too different
in size, but it will never be as good as allocating all from one unified
space.

The only valid factor that determines whether an allocation space should
be unified or partitioned is: does the *user* of the memory need to give
different interpretations to different allocation spaces?  E.g, highmem vs
zone_normal; one numa node vs another.

> Of course, this depends on how you are doing page
> reclamation. The idea should be to enable 
> architectures to use a single kswapd for all
> chunks, or have 1 per chunk, or some other
> combination.
> Basically, whatever is ideal for the architecture.

Hmm, I think there's are some basic principles at work here and that this
corner of the kernel can be much more consistent across architectures than
it is now.

-- 
Daniel