Date: Tue, 1 Dec 2009 17:23:59 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Darren Hart <dvhltc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
       Sripathi Kodi <sripathik@in.ibm.com>,
       Fr??d??ric Weisbecker <fweisbec@gmail.com>,
       Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org
Subject: Re: [RFC] [PATCH 0/2] Futex fault injection
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* Darren Hart <dvhltc@us.ibm.com> wrote:

> I don't think the "butt-ugly" argument is enough to reject the patch. 

It is in my book - i dont ever apply ugly patches intentionally.

> It's a fairly subjective metric and I don't think the proposed 
> solution results in "pretty" code either. In fact the super long 
> function names and multi-line conditionals are arguably "ugly" (maybe 
> not "butt-ugly" though). :-)
>
> However, the arguments are solid and I understand wanting to introduce 
> a new feature in a particular way. Has there been any work done on 
> perf event injection up to this point or would this be a completely 
> new perf feature?

Yeah, it would be a brand new one.

There's a couple of other usecases as well:

 - User space logging: apps want to define tracepoints and want to
   inject events as they happen - mixed properly into the regular perf
   events flow.

 - MCE logging: hw faults are so rare that injection is desired to make
   sure the policy action chain is working properly.

 - Some of the other fault injection sites could be converted to
   tracepoints + injection-conditions as well, perhaps. That would give
   a more programmable interface and a generic event logging framework.

So it's nice and important work (and by no means trivial - that comes 
with the territory) - in case you are interested.

Thanks,

	Ingo
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