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

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Message-ID: <CANLsYkxzSBHXGwe2y-593D4yDyLy9+vdcTHmP_rqF30x0qTiug@mail.gmail.com>
Date:	Thu, 28 Jul 2016 10:15:52 -0600
From:	Mathieu Poirier <mathieu.poirier@...aro.org>
To:	Jiri Olsa <jolsa@...hat.com>
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 27 July 2016 at 13:26, Jiri Olsa <jolsa@...hat.com> wrote:
> 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?

Indeed you do.

Macro ADD_CONFIG_TERM in function get_config_terms() only account for
the __val parameter and struct parse_events_term::config is completely
ignored.  We could concatenate the fields before calling
ADD_CONFIG_TERM() but between that and freeing the reserved memory, I
think it is cleaner to let flex do the work.

Mathieu

>
> 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