From: "H. Peter Anvin" <hpa@zytor.com>
To: Christoph Lameter <cl@linux.com>
Cc: Tejun Heo <tj@kernel.org>,
akpm@linux-foundation.org, Pekka Enberg <penberg@cs.helsinki.fi>,
linux-kernel@vger.kernel.org,
Eric Dumazet <eric.dumazet@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [cpuops cmpxchg double V1 2/4] x86: this_cpu_cmpxchg_double() support
Date: Tue, 14 Dec 2010 16:56:05 -0800 [thread overview]
Message-ID: <4D081225.8000007@zytor.com> (raw)
In-Reply-To: <4D080FDC.7030005@zytor.com>
On 12/14/2010 04:46 PM, H. Peter Anvin wrote:
> On 12/14/2010 09:48 AM, Christoph Lameter wrote:
>> +
>> +/*
>> + * Inputs:
>> + * %rsi : memory location to compare
>> + * %rax : low 64 bits of old value
>> + * %rdx : high 64 bits of old value
>> + * %rbx : low 64 bits of new value
>> + * %rcx : high 64 bits of new value
>> + * %al : Operation successful
>> + */
>> +ENTRY(cmpxchg16b_cpuops_emu)
>> +CFI_STARTPROC
>> +
>> +#
>> +# Emulate 'cmpxchg16b %gs:(%rsi)' except we return the result in
>> +# al not via the ZF. Caller will access al to get result.
>> +#
>
> NAK on this. This is acceptable for cmpxchg8b only because we don't
> support SMP on 486s anymore. x86-64 is another matter...
>
Hm, this is meant to be a CPU local operation, isn't it... it isn't very
clear from the comments or naming *in this file*.
Could you make it a little clearer in the local code, please?
-hpa
next prev parent reply other threads:[~2010-12-15 0:57 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-14 17:48 [cpuops cmpxchg double V1 0/4] this_cpu_cmpxchg_double support Christoph Lameter
2010-12-14 17:48 ` [cpuops cmpxchg double V1 1/4] Generic support for this_cpu_cmpxchg_double Christoph Lameter
2010-12-18 14:47 ` Tejun Heo
2010-12-18 14:51 ` Tejun Heo
2010-12-21 22:36 ` Christoph Lameter
2010-12-21 23:24 ` H. Peter Anvin
2010-12-22 9:14 ` Tejun Heo
2010-12-24 0:16 ` Christoph Lameter
2010-12-24 0:22 ` H. Peter Anvin
2010-12-25 4:53 ` Christoph Lameter
2010-12-25 6:11 ` H. Peter Anvin
2010-12-25 16:52 ` Tejun Heo
2010-12-25 23:55 ` Christoph Lameter
2010-12-27 10:52 ` Tejun Heo
2011-01-03 22:43 ` Christoph Lameter
2010-12-14 17:48 ` [cpuops cmpxchg double V1 2/4] x86: this_cpu_cmpxchg_double() support Christoph Lameter
2010-12-15 0:46 ` H. Peter Anvin
2010-12-15 0:56 ` H. Peter Anvin [this message]
2010-12-15 16:12 ` Christoph Lameter
2010-12-15 16:20 ` Christoph Lameter
2010-12-15 17:36 ` H. Peter Anvin
2010-12-15 17:53 ` Christoph Lameter
2010-12-15 16:32 ` H. Peter Anvin
2010-12-15 16:41 ` Christoph Lameter
2010-12-14 17:48 ` [cpuops cmpxchg double V1 3/4] slub: Get rid of slab_free_hook_irq() Christoph Lameter
2010-12-14 17:48 ` [cpuops cmpxchg double V1 4/4] Lockless (and preemptless) fastpaths for slub Christoph Lameter
2010-12-15 16:51 ` Tejun Heo
2010-12-15 16:55 ` Pekka Enberg
2010-12-15 16:57 ` Tejun Heo
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