Re: [PATCH] Separate global/perzone inactive/free shortage

[Dirk Wetter <dirkw@rentec.com>]

On Mon, 16 Jul 2001, Stephen C. Tweedie wrote:

> Hi,
>
> > On Sat, 14 Jul 2001, Marcelo Tosatti wrote:
>
> > On highmem machines, wouldn't it save a LOT of time to prevent allocation
> > of ZONE_DMA as VM pages?  Or, if we really need to, get those pages into
> > the swapcache instantly?  Crawling through nearly 4 gig of VM looking for
> > 16 MB of ram has got to be very expensive.  Besides, those pages are just
> > too precious to allow some user task to sit on them.
>
> Can't we balance that automatically?
>
> Why not just round-robin between the eligible zones when allocating,
> biasing each zone based on size?  On a 4GB box you'd basically end up
> doing 3 times as many allocations from the highmem zone as the normal
> zone and only very occasionally would you try to dig into the dma
> zone.  But on a 32MB box you would automatically spread allocations
> 50/50 between normal and dma, and on a 20MB box you would be biased in
> favour of allocating dma pages.

how good would be the one-size-fits-all approach?  certainly i would
like to have the best memory performance for my 4GB boxes, so does the
guy with the 20MB or 32MB box.  why not having yet another kernel config
option ;-) ?


cheers,
	~dirkw




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