linux-kernel - Re: disabling group leader perf

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Message-ID: <20100912184843.GB11165@elte.hu>
Date:	Sun, 12 Sep 2010 20:48:43 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Avi Kivity <avi@...hat.com>
Cc:	Pavel Machek <pavel@....cz>, Pekka Enberg <penberg@...helsinki.fi>,
	Tom Zanussi <tzanussi@...il.com>,
	Fr?d?ric Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-perf-users@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: disabling group leader perf_event


* Avi Kivity <avi@...hat.com> wrote:

>  On 09/12/2010 08:46 AM, Pavel Machek wrote:
> >  1- Most (least abstract) specific code: a block of bytecode in the form
> >     of a simplified, executable, kernel-checked x86 machine code block -
> >     this is also the fastest form. [yes, this is actually possible.]
> >Well... if we want to be a bit x86-entric.... can we just reuse ACPI
> >interpretter?
> 
> I hope this was a joke, ACPI won the academy awards for ugliness, 
> slowness, low performance, bad specification, non-generality, and 
> probably five other things I forgot.  Stay away from it as much as you 
> can.

It also combines the worst of the two worlds: it's the most specific 
type of code (almost like assembly), but has a very slow interpreter.

With 'x86 bytecode' the main (and pretty much only) point is to be able 
to execute the code as-is, once checked.

But, as i explained it before, i only consider it a theoretical 
possibility and i think that abstract code (such as ASCII text C source 
code) is a better solution.

Thanks,

	Ingo
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