Date: Fri, 16 Jan 2009 17:03:07 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Chris Mason <chris.mason@oracle.com>
Subject: Re: [PATCH 0/2] ftrace: updates to tip
Message-ID: <20090116160307.GA16612@elte.hu>
References: <20090116004050.273665842@goodmis.org> <20090116112345.GC20082@elte.hu> <alpine.DEB.1.10.0901160929300.22303@gandalf.stny.rr.com> <20090116152103.GA28643@elte.hu> <alpine.DEB.1.10.0901161050470.22303@gandalf.stny.rr.com> <20090116160202.GA15209@elte.hu>
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* Ingo Molnar <mingo@elte.hu> wrote:

> > [...] We can register a function to be traced via the function 
> > pointer, and we can pick which functions to trace, but we can not 
> > separate out different functions for different traces.
> 
> Why not? We could have a hash of all traced functions with metadata 
> attached. Since patching functions in/out would be a relatively rare 
> operation, this would be a highly efficient read-mostly hash.

We could build that hash when registering the tracer. Via recordmcount we 
have advance knowledge of all the functions that may be traced.

	Ingo
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