linux-kernel - Re: [RFC PATCH] x86, espfix: use spin

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Message-ID: <55559FDA.3010205@zytor.com>
Date:	Fri, 15 May 2015 00:27:22 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ingo Molnar <mingo@...nel.org>
CC:	Borislav Petkov <bp@...en8.de>, Gu Zheng <guz.fnst@...fujitsu.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [RFC PATCH] x86, espfix: use spin_lock rather than mutex

On 05/14/2015 11:54 PM, Ingo Molnar wrote:
>
> The only slightly subtle detail with that is to use alloc_pages_node()
> with the secondary CPU's node, to make sure the espfix stack is
> NUMA-local to the CPU that is going to use it.
>

It doesn't hurt, although it isn't super critical as each page will be 
shared among 64 CPUs.  The whole espfix stack is only a single cacheline 
long.

	-hpa

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