From: Artur Skawina <art.08.09@gmail.com>
To: Michael Breuer <mbreuer@majjas.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Mike Galbraith <efault@gmx.de>,
Arjan van de Ven <arjan@infradead.org>,
Joerg Roedel <joro@8bytes.org>
Subject: Re: x86 - cpu_relax - why nop vs. pause?
Date: Mon, 08 Feb 2010 14:33:06 +0100 [thread overview]
Message-ID: <4B701292.3030108@gmail.com> (raw)
In-Reply-To: <4B6F8A02.2060006@majjas.com>
Michael Breuer wrote:
> Just to move away from this... totally perplexed, I retested a bit.
> Seems something else had gone wrong causing me to try 'rep;pause' vs.
> 'pause'. The resulting opcode is f3 f3 90, as noted above.
>
> I do see what seems to be a small but noticeable performance improvement
> - no idea if there's a downside, and also no idea what f3 f3 90 does vs.
> f3 90. Might be something interesting, or maybe not.
Alignment? IOW what happens if you use eg "nop; rep; nop;" or "rep; nop; nop;"?
prev parent reply other threads:[~2010-02-08 13:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-07 17:28 x86 - cpu_relax - why nop vs. pause? Michael Breuer
2010-02-07 18:09 ` Joerg Roedel
2010-02-07 18:32 ` Arjan van de Ven
[not found] ` <1265566470.6280.10.camel@marge.simson.net>
2010-02-07 20:08 ` Michael Breuer
2010-02-07 21:15 ` Michael Breuer
2010-02-08 3:50 ` Michael Breuer
2010-02-08 13:33 ` Artur Skawina [this message]
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