linux-kernel - Re: [RFC PATCH 0/4] perf: Custom contexts

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Message-ID: <20110316175310.GA2861@ghostprotocols.net>
Date:	Wed, 16 Mar 2011 14:53:10 -0300
From:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
To:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Stephane Eranian <eranian@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Hitoshi Mitake <mitake@....info.waseda.ac.jp>,
	"2nddept-manager@....hitachi.co.jp" 
	<2nddept-manager@....hitachi.co.jp>
Subject: Re: [RFC PATCH 0/4] perf: Custom contexts

Em Thu, Mar 17, 2011 at 12:47:01AM +0900, Masami Hiramatsu escreveu:
> (2011/03/16 10:03), Frederic Weisbecker wrote:
> > Doh you're right. && would have two meaning.
> > No we should probably keep  a && b  has a meaning of we are
> > in the range a AND in the range b. Both at the same time, with
> > a evaluated first and then b. We also need to ensure than
> > a && b  doesn't mean the same than  b && a. You're right, perhaps
> > we need another operator to expression inclusion, or we need to
> > assume that specific meaning of &&.
> > 
> > For what I wanted to express in the example above, || seem be the
> > right choice: -e inst*@(..lock:*acquire(B) || lock:*release(B)..)
> > 
> > So || would mean union and && would mean inclusion.
> 
> Hmm, would we really need that kind of complex rules?
> It seems that we only need union case. If so, I'd suggest
> you to use ',' to express that, instead of ||.
> 
> -e inst*@(..lock:*acquire(B),lock:*release(B)..)

Yeah, I somehow was avoiding the comma operator because it could be used
to represent multiple events, but then its a different context, using it
to represent a circular list of ranges in the @ (at, location) expression
seems ok.

1. '..lock:*acquire(B)' is armed, 'lock:*release(B)..' isn't
2. '..lock:*acquire(B)' trigers, which causes 'lock:*release(B)..' to be
   armed
3. 'lock:*release(B)..' triggers, which causes '..lock:*acquire(B)' to
   be armed, rinse, repeat

- Arnaldo
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