linux-kernel - Re: [PATCH 1/3] Add prctl commands PR_GET_TSC and PR_SET

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Message-ID: <48027225.6000609@firstfloor.org>
Date:	Sun, 13 Apr 2008 22:50:45 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Erik Bosman <ejbosman@...vu.nl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Arjan van de Ven <arjan@...radead.org>,
	Andrea Arcangeli <andrea@...share.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] Add prctl commands PR_GET_TSC and PR_SET_TSC


>
> I think what Erik is trying to do is to make it possible to disable as
> many of these in the kernel as possible; I/O is easy, it's off by
> default; RDTSC and RDPMC can be disabled in the kernel, and I think
> even XSTORE can be disabled.

I'm a little sceptical it will work reliably, but we'll see.

There's also LSL (forgot that earlier). It is used by the vgetcpu()
because it's faster than CPUID or RDTSCP. Kernel
sets a magic segment up which has different limits for different CPUs.

-Andi

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