Re: [discuss] Re: 32-bit dma allocations on 64-bit platforms

[Andrea Arcangeli <andrea@suse.de>]

if you want to leave it disabled that's still fine with me as far as it
can be enabled in a optimal way (the one I like as usual is the 256/32
ratios of 2.4 ;), but I'm quite convinced that it will provide benefit
even if enabled, possibly with bigger ratios if you want less
"guaranteed" waste.

as usual if one doesn't want any ram and performance waste, x86-64 is
out there in production, and it'll avoid all the waste (unless you care
about wasting 16M of ram on a 4G box without the risk of failing
order 0 dma allocations on the intel implementation). If one want to go
cheap and buy x86 still then he must be prepared to potentially lose
900M of ram on a 32G box, it's a relative cost, so the more ram the more
memory will be potentially wasted, the less ram the less ram will be
potentially wasted.

the most frequent x86 highmem complains I ever got were related to
runing _out_ of lowmem zone with the lowmem zone _empty_. The day I will
get a complain for the lowmem being completely _free_ has yet to come ;).

thanks a lot for all the help.