Date: Mon, 30 May 2011 10:07:12 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Jan Beulich <JBeulich@novell.com>
Cc: Andy Lutomirski <luto@MIT.EDU>, Borislav Petkov <bp@alien8.de>,
        Jesper Juhl <jj@chaosbits.net>,
        richard -rw- weinberger <richard.weinberger@gmail.com>,
        Arjan van de Ven <arjan@infradead.org>,
        Mikael Pettersson <mikpe@it.uu.se>, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 08/10] x86-64: Emulate vsyscalls
Message-ID: <20110530080712.GH27557@elte.hu>
References: <cover.1306724657.git.luto@mit.edu>
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* Jan Beulich <JBeulich@novell.com> wrote:

> >>> On 30.05.11 at 05:48, Andy Lutomirski <luto@MIT.EDU> wrote:
> > This causes vsyscalls to be a little more expensive than real
> > syscalls.  Fortunately sensible programs don't use them.
> 
> Hmm - weren't vsyscalls there for performance reasons?

New code uses the vDSO. The fixed-address vsyscalls are apparently 
only used in esoteric cases like statically linked glibc binaries. 
(which should arguably be using the vDSO as well)

Thanks,

	Ingo
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