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Message-Id: <20110225173850.486326452@linux.com>
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Date: Fri, 25 Feb 2011 11:38:50 -0600
From: Christoph Lameter <cl@linux.com>
To: Tejun Heo <tj@kernel.org>
Cc: akpm@linux-foundation.org
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: linux-kernel@vger.kernel.org
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: [cpuops cmpxchg double V3 0/5] this_cpu_cmpxchg_double support
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This patch series introduces this_cpu_cmpxchg_double().

x86 cpus support cmpxchg16b and cmpxchg8b instuction which are capable of
switching two words instead of one during a cmpxchg.
Two words allow to swap more state in an atomic instruction.

this_cpu_cmpxchg_double() is used in the slub allocator to avoid
interrupt disable/enable in both alloc and free fastpath.
Using the new operation significantly speeds up the fastpaths.

V1->V2
	- Change parameter convention for this_cpu_cmpxchg_double. Specify both
	  percpu variables in same way as the two old and new values.
	- Do not require a per cpu pointer but a variable to conform to the
	  convention used in other this_cpu_ops.

V2->V3:
        - Do not use CONFIG_DEBUG_VM to enable cmpxchg diagnostics. Use
          custom SLUB define instead.
        - Add patch to move min_partial into a different cacheline.
        - Rediff