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Subject: Re: [PATCH][2.5] smp_call_function_mask
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Manfred Spraul <manfred@colorfullife.com>
Cc: Zwane Mwaikambo <zwane@holomorphy.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Date: 21 Jan 2003 23:14:49 +0000
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On Tue, 2003-01-21 at 07:13, Manfred Spraul wrote:
> Alan wrote:
> 
> >On Fri, 2003-01-17 at 05:18, Zwane Mwaikambo wrote:
> >> +	/* Wait for response */
> >> +	while (atomic_read(&data.started) != num_cpus)
> >> +		barrier();
> >
> >Only old old intel x86 that does -bad- things as it
> >generates a lot of bus locked cycles. Better to do
> >
> >	while(atomic_read(&data.started) != num_cpus)

> from 2.5.52, <asm-i386/atomic.h>
>     #define atomic_read(v)          ((v)->counter)
> AFAIK atomic_read never contained locked bus cycles.

For x86 at least it never did, you are right. Must be time for
a brain transplant



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