Messages in this thread | | | Date | Mon, 02 Apr 2007 13:38:39 -0700 | From | Martin Bligh <> | Subject | Re: [PATCH 1/4] x86_64: Switch to SPARSE_VIRTUAL |
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Christoph Lameter wrote: > 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.
The original plan when this was first merged was pretty much that - for sparsemem to replace discontigmem once it was well tested. Seems to have got stalled halfway through ;-(
Not sure we'll get away with replacing flatmem for all arches, but we could at least get rid of discontigmem, it seems.
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