On Wed, Jul 06, 2011 at 01:20:55PM -0700, david@xxxxxxx wrote: > On Wed, 6 Jul 2011, Pekka Enberg wrote: > > >Why does the allocator need to know about address boundaries? Why > >isn't it enough to make the page allocator and reclaim policies favor using > >memory from lower addresses as aggressively as possible? That'd mean > >we'd favor the first memory banks and could keep the remaining ones > >powered off as much as possible. > > > >IOW, why do we need to support scenarios such as this: > > > > bank 0 bank 1 bank 2 bank3 > >| online | offline | online | offline | > > I believe that there are memory allocations that cannot be moved > after they are made (think about regions allocated to DMA from > hardware where the hardware has already been given the address space > to DMA into) > Thats true. These are kernel allocations which are not movable. However, the ZONE_MOVABLE would enable us to create complete movable zones and the ones that have the kernel allocations could be flagged as kernelcore zone. > As a result, you may not be able to take bank 2 offline, so your > option is to either leave banks 0-2 all online, or support emptying > bank 1 and taking it offline. > -- Regards, Ankita Garg (ankita@xxxxxxxxxx) Linux Technology Center IBM India Systems & Technology Labs, Bangalore, India -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>