Re: [PATCH 0/4] V4 ia64 SPARSEMEM

[David Mosberger-Tang <David.Mosberger@acm.org>]

On 9/26/05, Luck, Tony <tony.luck@intel.com> wrote:

> >Long term should SPARSEMEM become the default and DISCONTIG+VIRTUAL_MEM_MAP
> >be obsoleted then we could remove the config files.
>
> If benchmarks show no difference, then I'll consolidate the
> configuration options.  I still think that VIRTUAL_MEM_MAP
> has a great deal of elegance to it ... auto-sizing to just
> about any degree of sparseness, but I think we need to
> simplify.

Benchmarks cannot prove the absence of a performance difference in
*general*, they can only do that for specific tests and workloads. 
So, unless SPARSEMEM actually performs *better* on some benchmarks
(and no worse on others), the proper course seems to be to stick with
VIRTUAL_MEM_MAP where SPARSEMEM isn't needed.

I have voice my objection in the past to Bob's suggestion that
SPARSEMEM should replace VIRTUAL_MEM_MAP and since then I haven't seen
any convincing argument why that should be the case, so I do not
understand why Bob keeps bringing that up.

  --david
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