Re: [PATCH 01/02] cpuset bitmap and mask remap operators

[Paul Jackson <pj@sgi.com>]

Andrew wrote:
> hm.  That hides what's really going on from the programmer.
> 
> Oh well - you're the only guy who dinks with that stuff anyway ;)

Halloween comes a week early to the Morton household.  The patch from
hell, circa April 2004, lives on to haunt Andrew <grin>.

By the time we (wli, rusty, colpatch, ...) incorporated the following
various constraints on these cpumask/nodemask macros, we were fortunate
to only violate the "obvious to the programmer" constraint on the
implementation internals:
  - near perfect code gen on small systems (1 word masks)
  - near perfect code gen on large systems (multiword masks)
  - type checking on arguments
  - keep the existing macro-style calling conventions:
	cpus_and(result, input1, input2)
  - a single bitmap internal implementation - the rest just wrappers
  - dramatic shinkage of kernel source devoted to this stuff
  - reduction in kernel text size across all architectures.

Probably it is best that we not ask too many questions at this time ;).

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                  Paul Jackson <pj@sgi.com> 1.925.600.0401