From: Pekka Enberg <penberg@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
"H. Peter Anvin" <hpa@zytor.com>,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [cpuops cmpxchg double V2 1/4] Generic support for this_cpu_cmpxchg_double
Date: Sun, 09 Jan 2011 10:33:43 +0200 [thread overview]
Message-ID: <1294562023.5248.120.camel@jaguar> (raw)
In-Reply-To: <20110108172453.GF13269@mtj.dyndns.org>
On Sat, 2011-01-08 at 12:24 -0500, Tejun Heo wrote:
> Hello,
>
> On Fri, Jan 07, 2011 at 12:41:58PM -0600, Christoph Lameter wrote:
> > On Fri, 7 Jan 2011, Mathieu Desnoyers wrote:
> >
> > > I have to admit that I also hate the current interface for two reasons:
>
> Call me weird but I like this one than others. It sure is ugly but
> the operation itself isn't a particularly pretty so it kinda matches.
> Also, this one is the least error prone and more consistent with other
> cpu ops.
>
> > > b) the loss of the value read (the fact that the only current user of this API
> > > does not need the value returned seems like a very weak argument to define an
> > > API).
> >
> > The other user of cmpxchg_double that I have in my tree also does not have
> > the need. Repeatability is not as simple to implement as with a single
> > word cmpxchg.
>
> Yeah, even in regular cmpxchg, the read value on failure isn't of very
> high value. The cpu usually has to go retry anyway && likely to have
> the cacheline already, so it's not gonna cost much.
>
> So, yeah, of the proposed ones, this is my favorite. Peter and
> Mathieu don't like it. What do others think? Pekka, Eric, Andrew,
> what do you guys think?
I'm not a huge fan of the API either but like you, I like it best from
the proposed ones.
Pekka
next prev parent reply other threads:[~2011-01-09 8:33 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-06 20:45 [cpuops cmpxchg double V2 0/4] this_cpu_cmpxchg_double support Christoph Lameter
2011-01-06 20:45 ` [cpuops cmpxchg double V2 1/4] Generic support for this_cpu_cmpxchg_double Christoph Lameter
2011-01-06 21:08 ` Mathieu Desnoyers
2011-01-06 21:43 ` Christoph Lameter
2011-01-06 22:05 ` H. Peter Anvin
2011-01-07 15:15 ` Christoph Lameter
2011-01-07 18:04 ` Mathieu Desnoyers
2011-01-07 18:41 ` Christoph Lameter
2011-01-08 17:24 ` Tejun Heo
2011-01-09 8:33 ` Pekka Enberg [this message]
2011-01-21 7:31 ` Pekka Enberg
2011-01-21 9:26 ` Tejun Heo
2011-01-21 15:31 ` H. Peter Anvin
2011-01-21 15:48 ` Tejun Heo
2011-01-21 16:30 ` H. Peter Anvin
2011-01-21 16:34 ` Tejun Heo
2011-01-21 16:54 ` Mathieu Desnoyers
2011-01-21 17:07 ` Christoph Lameter
2011-01-21 17:50 ` Mathieu Desnoyers
2011-01-21 18:06 ` Christoph Lameter
2011-01-21 18:37 ` Mathieu Desnoyers
2011-01-21 17:08 ` Tejun Heo
2011-01-21 17:13 ` H. Peter Anvin
2011-01-21 17:19 ` Tejun Heo
2011-01-24 6:01 ` H. Peter Anvin
2011-02-25 13:09 ` Pekka Enberg
2011-02-25 13:19 ` Tejun Heo
2011-02-25 16:26 ` Christoph Lameter
2011-02-25 16:37 ` Tejun Heo
2011-02-25 16:43 ` Christoph Lameter
2011-02-25 16:38 ` Eric Dumazet
2011-02-25 16:45 ` Christoph Lameter
2011-01-21 17:24 ` Christoph Lameter
2011-01-21 17:42 ` Mathieu Desnoyers
2011-01-21 17:50 ` Christoph Lameter
2011-01-21 18:10 ` Mathieu Desnoyers
2011-01-21 18:42 ` Christoph Lameter
2011-01-21 18:31 ` H. Peter Anvin
2011-01-21 18:46 ` Christoph Lameter
2011-01-21 19:32 ` Mathieu Desnoyers
2011-01-23 18:00 ` H. Peter Anvin
2011-01-06 20:45 ` [cpuops cmpxchg double V2 2/4] x86: this_cpu_cmpxchg_double() support Christoph Lameter
2011-01-06 20:45 ` [cpuops cmpxchg double V2 3/4] slub: Get rid of slab_free_hook_irq() Christoph Lameter
2011-01-06 20:45 ` [cpuops cmpxchg double V2 4/4] Lockless (and preemptless) fastpaths for slub Christoph Lameter
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