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

["Stephen C. Tweedie" <sct@redhat.com>]

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.

Cheers,
 Stephen
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