linux-kernel - Re: [cpuops cmpxchg double V2 1/4] Generic support for this_cpu_cmpxchg

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Date:	Fri, 25 Feb 2011 14:19:49 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Christoph Lameter <cl@...ux.com>, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [cpuops cmpxchg double V2 1/4] Generic support for
 this_cpu_cmpxchg_double

On Fri, Feb 25, 2011 at 03:09:26PM +0200, Pekka Enberg wrote:
> On Fri, Jan 21, 2011 at 09:13:41AM -0800, H. Peter Anvin wrote:
> >>>We could do cmpxchg with a structure... the problem with a lon int
> >>>type is that Cristoph ran into bugs with __int128 on 64 bits.
> 
> On 01/21/2011 09:19 AM, Tejun Heo wrote:
> >>But, IIRC, the problem with int128 was with passing it as parameter
> >>and return value. We don't have to do that. We'll be just using it
> >>as a data storage / container type. Or even that is broken?
> 
> On 1/24/11 8:01 AM, H. Peter Anvin wrote:
> >Well, part of the point was to pass in registers.
> >
> >No idea on the data storage type.
> 
> Ping? The current situation is that we're unable to merge a
> perfectly good SLUB performance optimization because we can't seem
> to agree on the this_cpu_cmpxchg_double() API.

I thought cl was preparing new version of the patchset.  Christoph?

-- 
tejun
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