From: "H. Peter Anvin" <hpa@zytor.com>
To: Christoph Lameter <cl@linux.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>, Tejun Heo <tj@kernel.org>,
akpm@linux-foundation.org, Pekka Enberg <penberg@cs.helsinki.fi>,
linux-kernel@vger.kernel.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [cpuops cmpxchg V2 5/5] cpuops: Use cmpxchg for xchg to avoid lock semantics
Date: Tue, 14 Dec 2010 09:00:39 -0800 [thread overview]
Message-ID: <4D07A2B7.8080405@zytor.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1012141055220.17229@router.home>
On 12/14/2010 08:55 AM, Christoph Lameter wrote:
>
> We do not need to reload the value as pointed out by Eric. It is already in
> the correct register so just rerun the cmpxchg without the load.
>
> Signed-off-by: Christoph Lameter <cl@linux.com>
>
Is it genuinely faster to do the pre-load mov, or can we drop that too?
My guess would be that yes it is, but if it happens not to be it would
be nice to reduce the code size.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2010-12-14 17:02 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-14 16:28 [cpuops cmpxchg V2 0/5] Cmpxchg and xchg operations Christoph Lameter
2010-12-14 16:28 ` [cpuops cmpxchg V2 1/5] percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support Christoph Lameter
2010-12-17 14:55 ` Tejun Heo
2010-12-14 16:28 ` [cpuops cmpxchg V2 2/5] x86: this_cpu_cmpxchg and this_cpu_xchg operations Christoph Lameter
2010-12-17 15:22 ` Tejun Heo
2010-12-14 16:28 ` [cpuops cmpxchg V2 3/5] irq_work: Use per cpu atomics instead of regular atomics Christoph Lameter
2010-12-15 16:32 ` Tejun Heo
2010-12-15 16:34 ` H. Peter Anvin
2010-12-15 16:50 ` Peter Zijlstra
2010-12-15 17:04 ` Christoph Lameter
2010-12-15 17:18 ` Peter Zijlstra
2010-12-15 17:31 ` H. Peter Anvin
2010-12-15 17:32 ` Christoph Lameter
2010-12-18 15:32 ` Tejun Heo
2010-12-14 16:28 ` [cpuops cmpxchg V2 4/5] vmstat: User per cpu atomics to avoid interrupt disable / enable Christoph Lameter
2010-12-15 16:45 ` Tejun Heo
2010-12-15 17:01 ` Christoph Lameter
2010-12-14 16:28 ` [cpuops cmpxchg V2 5/5] cpuops: Use cmpxchg for xchg to avoid lock semantics Christoph Lameter
2010-12-14 16:35 ` Mathieu Desnoyers
2010-12-14 16:44 ` Eric Dumazet
2010-12-14 16:55 ` Christoph Lameter
2010-12-14 17:00 ` H. Peter Anvin [this message]
2010-12-14 17:19 ` Christoph Lameter
2010-12-14 17:22 ` H. Peter Anvin
2010-12-14 17:29 ` Tejun Heo
2010-12-14 17:35 ` Christoph Lameter
2010-12-15 1:06 ` H. Peter Anvin
2010-12-15 16:29 ` Tejun Heo
2010-12-15 16:35 ` H. Peter Anvin
2010-12-15 16:39 ` Tejun Heo
2010-12-16 16:14 ` Tejun Heo
2010-12-16 18:13 ` x86: Use this_cpu_has for thermal_interrupt Christoph Lameter
2010-12-18 15:35 ` Tejun Heo
2010-12-21 0:56 ` H. Peter Anvin
2010-12-30 11:29 ` Tejun Heo
2010-12-30 18:19 ` H. Peter Anvin
2010-12-31 12:43 ` Tejun Heo
2010-12-16 18:14 ` x86: udelay: Use this_cpu_read to avoid address calculation Christoph Lameter
2010-12-16 18:15 ` gameport: use this_cpu_read instead of lookup Christoph Lameter
2010-12-18 15:34 ` Tejun Heo
2010-12-16 18:16 ` acpi throttling: Use this_cpu_has and simplify code Christoph Lameter
2010-12-18 15:50 ` Tejun Heo
2010-12-21 1:52 ` ykzhao
2010-12-21 22:43 ` Christoph Lameter
2010-12-21 4:28 ` Len Brown
2010-12-16 18:19 ` [cpuops cmpxchg V2 5/5] cpuops: Use cmpxchg for xchg to avoid lock semantics H. Peter Anvin
2010-12-16 18:55 ` Tejun Heo
2010-12-16 20:42 ` H. Peter Anvin
2010-12-15 16:47 ` Tejun Heo
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