linux-kernel - Re: [PATCH V2 3/6] perf tools: add infrastructure for PMU specific configuration

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Date:	Wed, 27 Jul 2016 21:26:39 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>, jolsa@...nel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V2 3/6] perf tools: add infrastructure for PMU specific
 configuration

On Wed, Jul 27, 2016 at 11:59:50AM -0600, Mathieu Poirier wrote:

SNIP

> > -PE_DRV_CFG_TERM
> > +'@' PE_NAME '=' PE_NAME
> >  {
> >         struct parse_events_term *term;
> >
> >         ABORT_ON(parse_events_term__str(&term, PARSE_EVENTS__TERM_TYPE_DRV_CFG,
> > -                                       $1, $1, &@1, NULL));
> > +                                       $2, $4, &@2, &@4));
> >         $$ = term;
> >  }
> >
> 
> The problem here is that the correlation between the first and the
> second PE_NAME is lost and instead of seeing "PE_NAME=PE_NAME", the
> kernel only gets the value associated with the second PE_NAME.
> 
> For example,
> 
> -e event/@...1=value1,@cfg2=value2/ ...
> 
> The above code will send "value1" and "value2" to the kernel driver
> where there is no way to know what configurable the values correspond

hum.. you get the 'cfg1' and 'cfg2' strings in $1 no?

jirka

> to.  To go around that we'd have to concatenate $2 and $4 in function
> parse_events_term__str() (or new_term()) when @type_term ==
> PARSE_EVENTS__TERM_TYPE_DRV_CFG, something that definitely looks
> hackish to me.
> 
> Thanks,
> Mathieu