linux-kernel - Re: [PATCH v8 3/4] perf config: Prepare all default configs

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Message-ID: <20160420132236.GM3677@kernel.org>
Date:	Wed, 20 Apr 2016 10:22:36 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Taeung Song <treeze.taeung@...il.com>,
	Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
	linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [PATCH v8 3/4] perf config: Prepare all default configs

Em Wed, Apr 20, 2016 at 09:44:38PM +0900, Namhyung Kim escreveu:
> On Mon, Apr 18, 2016 at 11:55:18PM +0900, Taeung Song wrote:
> > On 04/15/2016 01:42 AM, Taeung Song wrote:
> > > On 04/14/2016 09:19 PM, Arnaldo Carvalho de Melo wrote:
> > > > Em Thu, Apr 14, 2016 at 04:53:20PM +0900, Taeung Song escreveu:
> > > > > +++ b/tools/perf/util/config.c
> > > > > @@ -15,6 +15,7 @@
> > > > > +#define MAX_CONFIGS 64

> > > > Do we have to add another arbitrary maximum? Where is it used?

> > > IMHO, it is my idea. If you want to avoid using this arbitrary maxinum,
> > > I'd modify the code.
> > > 
> > > MAX_CONFIGS is used in order to declare two-dimensional arrays
> > > 'default_config_items'

> > As above, I used MAX_CONFIGS because of two-dimensinal arrays
> > 'default_config_items'.

> > What do you think about it ?
 
> I also agree that we'd better to avoid the arbitrary maximum.

> > We don't need to add this arbitrary maximum ?
> > or would you mind, if I look for other way about
> > 'default_config_item' ?
> 
> What about this?

Yeah, I guess this should work, no? At least this is how it is done
elsewhere, see:

tools/perf/builtin-bench.c, 'struct collection' has a benchmarks array,
that in turn is organized as Namhyung suggests.

Then you either use ARRAY_SIZE() somewhere to get the number of entries
or use a sentinel, i.e. use NULL for the last entry.

- Arnaldo
 
> struct perf_config_item color_config_items[] = {
> 	CONF_STR_VAR("top", "red, default"),
> 	CONF_STR_VAR("medium", "green, default"),
> 	...
> };
> 
> struct perf_config_item tui_config_items[] = {
> 	CONF_BOOL_VAR("report", true),
> 	CONF_BOOL_VAR("annotate", true),
> 	...
> };
> 
> struct perf_config_item *default_config_items[] = {
> 	&color_config_items,
> 	&tui_config_items,
> 	...
> };
> 
> This way we can access the config array by using constant index
> without the hard-coded maximum size IMHO.
> 
> Thanks,
> Namhyung