From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1751224AbaH3IyJ (ORCPT <rfc822;w@1wt.eu>);
	Sat, 30 Aug 2014 04:54:09 -0400
Received: from mx1.redhat.com ([209.132.183.28]:4466 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751059AbaH3IyG (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Sat, 30 Aug 2014 04:54:06 -0400
Date: Sat, 30 Aug 2014 10:53:10 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org,
        David Ahern <dsahern@gmail.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Namhyung Kim <namhyung@gmail.com>, Paul Mackerras <paulus@samba.org>,
        Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH 20/41] perf tools: Let a user specify a PMU event without
 any config terms
Message-ID: <20140830085310.GA14358@krava.redhat.com>
References: <1405332185-4050-1-git-send-email-adrian.hunter@intel.com>
 <1405332185-4050-21-git-send-email-adrian.hunter@intel.com>
 <20140716142510.GE9441@krava.redhat.com>
 <53C6948C.2080103@intel.com>
 <20140716182214.GB32716@krava.redhat.com>
 <5400CB13.4040004@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <5400CB13.4040004@intel.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Aug 29, 2014 at 09:48:51PM +0300, Adrian Hunter wrote:
> On 16/07/2014 9:22 p.m., Jiri Olsa wrote:
> >On Wed, Jul 16, 2014 at 06:04:44PM +0300, Adrian Hunter wrote:
> >>On 16/07/2014 5:25 p.m., Jiri Olsa wrote:
> >>>On Mon, Jul 14, 2014 at 01:02:44PM +0300, Adrian Hunter wrote:
> >>>>This enables a PMU event to be specified in the form:
> >>>>
> >>>>	pmu//
> >>>>
> >>>>which is effectively the same as:
> >>>>
> >>>>	pmu/config=0/
> >>>>
> >>>>This patch is a precursor to defining
> >>>>default config for a PMU.
> >>>
> >>>I understand the need for default config, but could you please elaborate
> >>>why do we want to parse 'pmu//' as an event string string?
> >>
> >>Currently the parser requires the slashes to identify a PMU event
> >>as opposed to a hardware or other kind of event.
> >
> >right, so why do we want to parse 'pmu//' as an event string? ;-)
> 
> I am not sure what you mean.  Here I am using 'pmu' as a placeholder
> for a real PMU name.  So actual event strings are 'intel_bts//' or
> 'intel_pt//' or 'intel_pt/tsc=0,noretcomp=1/'

so the consequence of default arguments is that you can
specify event just by the pmu name, like:
  -e intel_pt//

which means (with default attributes):
  -e intel_pt/tsc=1,noretcomp=0/

I guess I wanted to hear more elaboration why is this better
than the current way we have by defining an alias, like:

  krava alias: "tsc=1,noretcomp=0"

  -e intel_pt/krava/

which gives the same result

thanks,
jirka