large pages (amd64)

Wojciech Puchar wojtek at
Sun Jun 28 17:39:42 UTC 2009

i enabled
vm.pmap.pg_ps_enabled: 1

could you please explain what exactly this values means?
because i don't understand why promotions-demotions!=mappings

vm.pmap.pde.promotions: 2703
vm.pmap.pde.p_failures: 6290
vm.pmap.pde.mappings: 610
vm.pmap.pde.demotions: 289

other question - tried enabling it on my i386 laptop (256 megs ram), 
always mappings==0, while promitions>demotions>0.

certainly there are apps that could be put on big pages, gimp editing 40MB 
bitmap for example

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