Date: Sun, 18 Jan 2009 08:27:53 +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: <20090118072753.GA3398@elte.hu>
References: <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> <alpine.DEB.1.10.0901161111490.22303@gandalf.stny.rr.com> <20090116163021.GA27495@elte.hu> <20090116225948.GA12314@elte.hu> <alpine.DEB.1.10.0901162003000.9232@gandalf.stny.rr.com> <20090117223451.GA27065@elte.hu>
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* Ingo Molnar <mingo@elte.hu> wrote:

> 
> * Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> > > This would allow the creation of "surgical" one-time traces - of 
> > > events and functions one is specifically interested in.
> > 
> > This all sounds great, but it would add a lot of conditionals into a 
> > extremely hot function tracer path. [...]
> 
> Why would we need more than exactly one unlikely() condition to handle 
> all of this?

We could even do it with zero branches, burdening none of the hotpaths of 
existing functionality. Hm?

	Ingo
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