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Date: Wed, 17 Jun 2009 14:24:55 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>, mingo@redhat.com, hpa@zytor.com,
       paulus@samba.org, acme@redhat.com, linux-kernel@vger.kernel.org,
       penberg@cs.helsinki.fi, efault@gmx.de, arjan@infradead.org,
       tglx@linutronix.de, linux-tip-commits@vger.kernel.org,
       Corey Ashford <cjashfor@linux.vnet.ibm.com>
Subject: Re: [tip:perfcounters/core] perf record/report: Add call graph /
	call chain profiling
Message-ID: <20090617122455.GC13316@elte.hu>
References: <tip-3efa1cc99ec51bc7a7ae0011a16619fd20dbe6ea@git.kernel.org> <20090616025750.GB6057@nowhere> <20090616080924.GB16229@elte.hu> <1245224279.13761.21585.camel@twins>
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* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> > The context IDs would occupy some rare and 
> > unlikely-to-be-allocated-soon corner of the address space - say 
> > startig at 0x8765432112345000. (and real RIPs would be filtered 
> > and nudged just outside that space of a handful IDs.)
> 
> Right, that works too, but should we use (u64)-1..-4095 for that? 
> We already use that range for things like ERR_PTR() so its very 
> unlikely we have something sensible mapped there.

Makes sense. It's also an easier (and more natural) enumeration 
method.

	Ingo