Date: Mon, 22 Mar 2004 18:09:40 -0800
From: William Lee Irwin III <wli@holomorphy.com>
To: Paul Jackson <pj@sgi.com>
Cc: colpatch@us.ibm.com, linux-kernel@vger.kernel.org, mbligh@aracnet.com,
       akpm@osdl.org, haveblue@us.ibm.com, hch@infradead.org
Subject: Re: [PATCH] Introduce nodemask_t ADT [0/7]
Message-ID: <20040323020940.GV2045@holomorphy.com>
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On Mon, Mar 22, 2004 at 05:12:43PM -0800, Paul Jackson wrote:
> I'm not trying to get on your case, Bill, for not creating and applying
> more various cpumask functions.  Rather I am looking for ways to make
> that API easier for others to use and use well.  If the situations that
> passed about temporary cpumasks can be collapsed into single calls that
> are more efficient, then that is one way to make progress on this.
> Taking masks to be a struct of an array of unsigned longs seems to come
> pretty close.  The sparc64 arch would want to pass a pointer to this
> apparently, rather than the struct itself - faster for them. Some other
> smaller archs would _not_ want to pass a pointer, but rather the (one
> word, for them) value - avoids a dereference for them.  In arch specific
> code, each arch can choose which way works best for them.  I need to
> identify any generic code where these preferences collide.

I generally like the idea of the arches getting their choice here (heck,
even wrt. representation; e.g. some arch might want an array of cpuid
numbers and not a bitmap at all due to extremely sparse cpuid's or some
such nonsense). The asm-generic stuff was largely a question of
reducing diffsize, preemptive code consolidation, etc.

I don't believe normal C (i.e. sans typedef) will allow needed
ambiguities that make UP/small SMP/etc. compile things out nicely, but
if you can get the requirement of the stuff totally compiling out
dropped or do it in normal C somehow, go for it. I'd call it a cleanup.


-- wli
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