linux-kernel - Re: [Use cpuops V1 05/11] core: Replace __get_cpu_var with __this_cpu

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Message-ID: <4CFFA31E.6080709@kernel.org>
Date:	Wed, 08 Dec 2010 16:24:14 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Christoph Lameter <cl@...ux.com>
CC:	akpm@...ux-foundation.org, Pekka Enberg <penberg@...helsinki.fi>,
	Hugh Dickins <hughd@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org,
	Eric Dumazet <eric.dumazet@...il.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [Use cpuops V1 05/11] core: Replace __get_cpu_var with __this_cpu_read
 if not used for an address.

On 12/07/2010 04:38 PM, Christoph Lameter wrote:
> On Tue, 7 Dec 2010, Tejun Heo wrote:
> 
>> Can you please fold this into the original patch and resend?  I
>> skipped 04, 05 and 09.  percpu#for-next now contains other patches.
>>
>>   git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu.git for-next
>>
>> Thanks.
> 
> Subject: core: Replace __get_cpu_var with __this_cpu_read if not used for an address.
> 
> __get_cpu_var() can be replaced with this_cpu_read and will then use a single
> read instruction with implied address calculation to access the correct per cpu
> instance.
> 
> However, the address of a per cpu variable passed to __this_cpu_read() cannot be
> determed (since its an implied address conversion through segment prefixes).
> Therefore apply this only to uses of __get_cpu_var where the addres of the
> variable is not used.
> 
> Cc: Pekka Enberg <penberg@...helsinki.fi>
> Cc: Hugh Dickins <hughd@...gle.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Christoph Lameter <cl@...ux.com>

Applied.  Thanks.

-- 
tejun
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