Re: [PATCH 1/4] x86_64: Switch to SPARSE_VIRTUAL

Christoph Lameter
2007-04-02T20:30:57Z

On Mon, 2 Apr 2007, Dave Hansen wrote:

> I completely agree, it looks like it should be faster. The code
> certainly has potential benefits. But, to add this neato, apparently
> more performant feature, we unfortunately have to add code. Adding the
> code has a cost: code maintenance. This isn't a runtime cost, but it is
> a real, honest to goodness tradeoff.

Its just the opposite. The vmemmap code is so efficient that we can remove
lots of other code and gops of these alternate implementations. On x86_64
its even superior to FLATMEM since FLATMEM still needs a memory reference
for the mem_map area. So if we make SPARSE standard for all
configurations then there is no need anymore for FLATMEM DISCONTIG etc
etc. Can we not cleanup all this mess? Get rid of all the gazillions
of #ifdefs please? This would ease code maintenance significantly. I hate
having to constantly navigate my way through all the alternatives.