Date: Thu, 3 Jun 2004 22:30:05 -0700
From: Paul Jackson <pj@sgi.com>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: rusty@rustcorp.com.au, linux-kernel@vger.kernel.org, akpm@osdl.org,
       ak@muc.de, ashok.raj@intel.com, hch@infradead.org, jbarnes@sgi.com,
       joe.korty@ccur.com, manfred@colorfullife.com, colpatch@us.ibm.com,
       mikpe@csd.uu.se, Simon.Derr@bull.net, wli@holomorphy.com
Subject: Re: [PATCH] cpumask 5/10 rewrite cpumask.h - single bitmap based
 implementation
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> I don't see what you gain from having the cpumask type but having
> to get at its internals with the bitop functions.

The essential gain, in my view, of cpumask, is that it encapsulates
the value NR_CPUS.  cpumasks are bitmaps of length NR_CPUS.

Yes, there is an open issue of whether cpumasks are worth it.
I think enough code has taken to them that they are.

The getting at internals (via cpus_addr(), I'm guessing you mean)
was a workaround for some code that messed with cpumasks and simple
unsigned longs as if they were interoperable.  "cpus_addr" should
be marked deprecated, and its use coded out.  Its remaining uses
are in arch-specific areas where I lack the expertise and testing
environment to accomplish such.

I needed some legacy mechanism such as this, in order to avoid
having such existing uses bring the entire cpumask overhaul to
a screeching halt.

-- 
                          I won't rest till it's the best ...
                          Programmer, Linux Scalability
                          Paul Jackson <pj@sgi.com> 1.650.933.1373
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