From: Eric Dumazet <eric.dumazet@gmail.com>
To: Christoph Lameter <cl@linux.com>
Cc: Tejun Heo <tj@kernel.org>,
akpm@linux-foundation.org, Yinghai Lu <yinghai@kernel.org>,
Ingo Molnar <mingo@elte.hu>,
Pekka Enberg <penberg@cs.helsinki.fi>,
linux-kernel@vger.kernel.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [PATCH] x86: Replace uses of current_cpu_data with this_cpu ops
Date: Wed, 08 Dec 2010 18:17:26 +0100 [thread overview]
Message-ID: <1291828646.2883.65.camel@edumazet-laptop> (raw)
In-Reply-To: <alpine.DEB.2.00.1012080929590.23407@router.home>
Le mercredi 08 décembre 2010 à 09:33 -0600, Christoph Lameter a écrit :
> On Wed, 8 Dec 2010, Eric Dumazet wrote:
>
> > > In the long run, it might be a good idea to remove cpu_data() macro
> > > too and use per_cpu macro directly.
> > >
> >
> > or introduce this_cpu_has() to remove the adress computation
> >
> > - if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_ARAT)) {
> >
> > + if (this_cpu_has(X86_FEATURE_ARAT)) {
> >
>
> The fundamental problem is that bitops require memory addresses which does
> not work with per cpu ops.
>
Sure, set() or clear() needs the address, but the read doesnt ?
This can be implemented as
(__this_cpu_read(cpu_info.word[X]) & MASK)
Anyway, even if mapped to cpu_has(__this_cpu_ptr(&cpu_info), XXX),
it would be cleaner to use this_cpu_has() helper.
next prev parent reply other threads:[~2010-12-08 17:17 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-06 17:16 [Use cpuops V1 00/11] Use this_cpu_ops Christoph Lameter
2010-12-06 17:16 ` [Use cpuops V1 01/11] percpucounter: Optimize __percpu_counter_add a bit through the use of this_cpu() options Christoph Lameter
2010-12-07 13:59 ` Tejun Heo
2010-12-06 17:16 ` [Use cpuops V1 02/11] vmstat: Optimize zone counter modifications through the use of this cpu operations Christoph Lameter
2010-12-07 14:00 ` Tejun Heo
2010-12-06 17:16 ` [Use cpuops V1 03/11] x86: Use this_cpu_ops to optimize code Christoph Lameter
2010-12-06 17:16 ` [Use cpuops V1 04/11] x86: Use this_cpu_ops for current_cpu_data accesses Christoph Lameter
2010-12-07 14:17 ` Tejun Heo
2010-12-07 14:20 ` Tejun Heo
2010-12-07 14:46 ` Christoph Lameter
2010-12-07 14:59 ` Tejun Heo
2010-12-07 15:07 ` Christoph Lameter
2010-12-07 15:08 ` Tejun Heo
2010-12-07 16:21 ` Christoph Lameter
2010-12-08 13:16 ` [PATCH] x86: Replace uses of current_cpu_data with this_cpu ops Tejun Heo
2010-12-08 13:38 ` Eric Dumazet
2010-12-08 15:33 ` Christoph Lameter
2010-12-08 17:17 ` Eric Dumazet [this message]
2010-12-08 17:20 ` Tejun Heo
2010-12-08 17:33 ` Christoph Lameter
2010-12-08 17:57 ` Tejun Heo
2010-12-06 17:16 ` [Use cpuops V1 05/11] core: Replace __get_cpu_var with __this_cpu_read if not used for an address Christoph Lameter
2010-12-07 14:29 ` Tejun Heo
2010-12-07 14:51 ` Christoph Lameter
2010-12-07 15:21 ` Tejun Heo
2010-12-07 15:38 ` Christoph Lameter
2010-12-08 15:24 ` Tejun Heo
2010-12-06 17:16 ` [Use cpuops V1 06/11] drivers: " Christoph Lameter
2010-12-07 14:31 ` Tejun Heo
2010-12-06 17:16 ` [Use cpuops V1 07/11] kprobes: Use this_cpu_ops Christoph Lameter
2010-12-07 15:03 ` Tejun Heo
2010-12-06 17:16 ` [Use cpuops V1 08/11] Fakekey: Simplify speakup_fake_key_pressed through this_cpu_ops Christoph Lameter
2010-12-07 15:07 ` Tejun Heo
2010-12-06 17:16 ` [Use cpuops V1 09/11] Connector: Use this_cpu operations Christoph Lameter
2010-12-07 15:08 ` Tejun Heo
2010-12-07 15:36 ` Christoph Lameter
2010-12-06 17:16 ` [Use cpuops V1 10/11] fs: Use this_cpu_xx operations in buffer.c Christoph Lameter
2010-12-07 15:16 ` Tejun Heo
2010-12-06 17:16 ` [Use cpuops V1 11/11] Xen: Use this_cpu_ops Christoph Lameter
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