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Date: Sun, 8 Nov 2009 13:55:27 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Stefani Seibold <stefani@seibold.net>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       "H. Peter Anvin" <hpa@zytor.com>,
       Americo Wang <xiyou.wangcong@gmail.com>,
       Thomas Gleixner <tglx@linutronix.de>, Andi Kleen <andi@firstfloor.org>
Subject: Re: [PATCH] RFC x86_64 more accurate KSTK_ESP implementation
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* Stefani Seibold <stefani@seibold.net> wrote:

> > I'd suggest a competely different method: why dont you use an IPI to 
> > sample the SP whenever someone wants to read it from /proc and we 
> > see that the task is running on a CPU right now?
> 
> Sounds like a challenge, i like the idea. I will have a look on it...

It's not a fastpath, so smp_function_call() ought to do the trick.

	Ingo