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From: Ingo Molnar <mingo@elte.hu>
To: Paul Mackerras <paulus@samba.org>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH] Define __raw_get_cpu_var and use it
Date: Wed, 10 May 2006 09:09:29 +0200	[thread overview]
Message-ID: <20060510070929.GA23414@elte.hu> (raw)
In-Reply-To: <17505.24133.491523.358882@cargo.ozlabs.ibm.com>


* Paul Mackerras <paulus@samba.org> wrote:

> There are several instances of per_cpu(foo, raw_smp_processor_id()), 
> which is semantically equivalent to __get_cpu_var(foo) but without the 
> warning that smp_processor_id() can give if CONFIG_DEBUG_PREEMPT is 
> enabled.  For those architectures with optimized per-cpu 
> implementations, namely ia64, powerpc, s390, sparc64 and x86_64, 
> per_cpu() turns into more and slower code than __get_cpu_var(), so it 
> would be preferable to use __get_cpu_var on those platforms.
> 
> This defines a __raw_get_cpu_var(x) macro which turns into per_cpu(x, 
> raw_smp_processor_id()) on architectures that use the generic per-cpu 
> implementation, and turns into __get_cpu_var(x) on the architectures 
> that have an optimized per-cpu implementation.
>     
> Signed-off-by: Paul Mackerras <paulus@samba.org>

i made the original raw_smp_processor_id() changes and i never liked the 
per_cpu() open-coding it introduced. Your patch solves this problem 
nicely.

Acked-by: Ingo Molnar <mingo@elte.hu>

	Ingo

  parent reply	other threads:[~2006-05-10  7:09 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-05-10  3:30 [PATCH] Define __raw_get_cpu_var and use it Paul Mackerras
2006-05-10  6:17 ` David S. Miller
2006-05-10  7:09 ` Ingo Molnar [this message]
2006-05-10  8:39 ` Martin Schwidefsky

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