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Subject: Re: [PATCH 8/5] llist: Remove cpu_relax() usage in cmpxchg loops
From: Peter Zijlstra <peterz@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andi Kleen <andi@firstfloor.org>, Huang Ying <ying.huang@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org
Date: Mon, 12 Sep 2011 17:24:20 +0200
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On Mon, 2011-09-12 at 17:09 +0200, Peter Zijlstra wrote:

> Furthermore, I would argue we should avoid growing them, significantly
> contended atomic ops are bad, use a different scheme.

To clarify, plain cmpxchg loops are unfair and unbounded in completion
time, and we should therefore avoid any sort of medium/high contention.
If you get into that situation you're doing it wrong.