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From: Tejun Heo <tj@kernel.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>, Ingo Molnar <mingo@elte.hu>,
	Thomas Gleixner <tglx@linutronix.de>,
	x86@kernel.org, Christoph Lameter <cl@linux.com>,
	linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Pekka Enberg <penberg@kernel.org>
Subject: Re: [PATCH tip:x86/mm 1/3] x86: A fast way to check capabilities of the current cpu
Date: Wed, 30 Mar 2011 18:07:56 +0200	[thread overview]
Message-ID: <20110330160756.GL17523@htj.dyndns.org> (raw)
In-Reply-To: <4D93531F.5080403@zytor.com>

Hello,

On Wed, Mar 30, 2011 at 08:58:23AM -0700, H. Peter Anvin wrote:
> >> Add this_cpu_has() which determines if the current cpu has a certain
> >> ability using a segment prefix and a bit test operation.
> > 
> > 
> > Hmm: if the CPU capability is really tested in a performance critical
> > path, wouldn't it even be better to just use static_branch() now? 
> > 
> 
> We have static_cpu_has() for this specific purpose (it actually predates
> static_branch()).

These patches have performance benefits but I don't think it would be
noticeable.  I think it's more of code cleanup.

Thanks.

-- 
tejun

  reply	other threads:[~2011-03-30 16:08 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-12 11:50 Tejun Heo
2011-03-12 11:50 ` [PATCH tip:x86/mm 2/3] x86: Use this_cpu_has for thermal_interrupt " Tejun Heo
2011-03-12 11:51   ` [PATCH tip:x86/mm 3/3] acpi throttling: Use this_cpu_has and simplify code " Tejun Heo
2011-03-28 16:40     ` Tejun Heo
2011-03-30 14:20       ` Christoph Lameter
2011-03-30 15:19         ` Tejun Heo
2011-03-14 19:49 ` [PATCH tip:x86/mm 1/3] x86: A fast way to check capabilities of the " Andi Kleen
2011-03-30 15:58   ` H. Peter Anvin
2011-03-30 16:07     ` Tejun Heo [this message]
2011-03-30 16:15       ` Christoph Lameter
2011-03-30 16:16     ` H. Peter Anvin

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