linux-kernel - Re: [PATCH 3/6] x86: Add support for the clwb instruction

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Date:	Tue, 11 Nov 2014 20:54:38 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org,
	H Peter Anvin <h.peter.anvin@...el.com>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org, x86@...nel.org
Subject: Re: [PATCH 3/6] x86: Add support for the clwb instruction

On Tue, Nov 11, 2014 at 12:48:52PM -0700, Ross Zwisler wrote:
> Essentially we need one additional byte at the beginning of the clflush so
> that we can flip it into a clflushopt by changing that byte into a 0x66
> prefix.  Two options are to either insert a 1 byte ASM_NOP1, or to add a 1
> byte NOP_DS_PREFIX.  Both have no functional effect with the plain clflush,
> but I've been told that executing a clflush + prefix should be faster than
> executing a clflush + NOP.

I see. :)

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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