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From: Arnd Bergmann <arnd@arndb.de>
To: Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] cpuacct: add a branch prediction
Date: Thu, 26 Feb 2009 13:40:56 +0100
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Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       Bharata B Rao <bharata.rao@gmail.com>, Li Zefan <lizf@cn.fujitsu.com>,
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On Thursday 26 February 2009, Ingo Molnar wrote:
>
> > Yeah, atomic64_t has been proposed numerous times, and x86 
> > could actually implement that using cmpxchg8b, just not sure 
> > about all the other 32bit archs, and if we start using it in 
> > the scheduler, they'd better have it implemented.
> 
> I have written a working atomic64_t implementation for 
> tip:perfcounters/core, for 32-bit x86.

It should also be possible to write an asm-generic atomic64_t
implementation based on the parisc atomic_t hashlock code.
For non-SMP configurations, it falls back on local_irq_save(),
which is already the method used for atomic_t on half the
embedded architectures.

	Arnd <><