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Date: Mon, 20 Dec 2010 23:28:03 -0500 (EST)
From: Len Brown <lenb@kernel.org>
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To: Christoph Lameter <cl@linux.com>
Cc: Tejun Heo <htejun@gmail.com>, "H. Peter Anvin" <hpa@zytor.com>,
        Eric Dumazet <eric.dumazet@gmail.com>, akpm@linux-foundation.org,
        Pekka Enberg <penberg@cs.helsinki.fi>, linux-kernel@vger.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: acpi throttling: Use this_cpu_has and simplify code
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This patch is a valid cleanup, and I've applied it to the acpi-test tree.

The routines named *rdmsr() and *wrmsr() run on the local CPU
by definition.  I think that after this change to get rid of pr*,
that is even more clear.

The part about checking that you are on the right processor
should really be done in the caller.  Yakui should send a patch
for the driver to check for successful return from
set_cpus_allowed_ptr() before invoking this code.

> With the this_cpu_xx we no longer need to pass an acpi
> structure to the msr management code. Simplifies code and improves
> performance.

Simplifies, yes.
Performance -- not the focus here.
If you are running routines to throttle the clock frequency,
then you have already decided that performance isn't your top priority:-)

thanks,
Len Brown, Intel Open Source Technology Center

> Signed-off-by: Christoph Lameter <cl@linux.com>
> 
> ---
>  drivers/acpi/processor_throttling.c |   32 ++++++++++----------------------
>  1 file changed, 10 insertions(+), 22 deletions(-)