Re: disabling group leader perf_event

From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@redhat.com>
Cc: Pavel Machek <pavel@ucw.cz>,
	Pekka Enberg <penberg@cs.helsinki.fi>,
	Tom Zanussi <tzanussi@gmail.com>,
	Fr?d?ric Weisbecker <fweisbec@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-perf-users@vger.kernel.org,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: disabling group leader perf_event
Date: Sun, 12 Sep 2010 20:48:43 +0200	[thread overview]
Message-ID: <20100912184843.GB11165@elte.hu> (raw)
In-Reply-To: <4C8D13CD.1060802@redhat.com>

* Avi Kivity <avi@redhat.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