Date:	Fri, 10 Jun 2016 19:58:46 +0900
From:	Taeung Song <treeze.taeung@...il.com>
To:	Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:	linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Wang Nan <wangnan0@...wei.com>, Jiri Olsa <jolsa@...hat.com>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v8 3/5] perf config: Reimplement perf_config() using
 perf_config_set__iter()



On 06/09/2016 10:34 PM, Arnaldo Carvalho de Melo wrote:
> Em Wed, Jun 08, 2016 at 09:36:51PM +0900, Taeung Song escreveu:
>> Many sub-commands use perf_config() so
>> everytime perf_config() is called, perf_config() always read config files.
>> (i.e. user config '~/.perfconfig' and system config '$(sysconfdir)/perfconfig')
>
> And this is not always a bad thing, think about being in 'mutt' and
> adding an entry to ~/.mail_aliases, then going to compose a message,
> would be good that the just added entry to ~/.mail_aliases be considered
> when adding recipients to your messages, right?
>
> In the same fashion, 'perf report', 'perf annotate', 'perf top' are long
> running utilities that have operations that could get changes to config
> files without having to restart them, i.e. do annotation changes in your
> ~/.perfconfig and then see them reflected next time you hit 'A´ to
> annotate a function in 'perf top' or 'perf report'.
>

Currently, this suggestion isn't already contained among features of 
perf. right?

I understood that you mean while perf process is already running
if user change a config file, the changed config can be reflected in
'perf top', 'perf report' or etc without restarting perf process like mutt.
Is it right ?

> So, I think that if tools want ammortize the cost of reading config
> files, they should create an instance of the relevant object
> (perf_config_set?) use it and then delete it, but not keep one around
> for a long time.
>

I got it.

How about the two ideas that I have in mind ?

1) If we eliminate the config set object(perf_config_set) after using it
because we don't need to keep it until perf process is done,

we could bring many codes using perf_config() at one spot of perf.c ?
(because it is hard to decide a point of time we destroy the config set.)
For example,

(This code isn't executable)

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 15982ce..6a56985 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -77,6 +77,23 @@ struct pager_config {
          int val;
  };

+static void perf_default_config_init(void)
+{
+        default_colors_config_init();
+        default_annoate_config_init();
+        default_report_config_init();
+        ...
+}
+
+static void perf_config_init(void)
+{
+        perf_default_config_init();
+        colors_config_init();
+        annotate_config_init();
+        report_config_init();
+        ...
+}
+
  static int pager_command_config(const char *var, const char *value, 
void *data)
  {
          struct pager_config *c = data;
@@ -558,7 +575,7 @@ int main(int argc, const char **argv)

          srandom(time(NULL));

-        perf_config(perf_default_config, NULL);
+        perf_config_init();
          set_buildid_dir(NULL);

          /* get debugfs/tracefs mount point from /proc/mounts */
diff --git a/tools/perf/ui/browser.c b/tools/perf/ui/browser.c
index af68a9d..4b827c2 100644
--- a/tools/perf/ui/browser.c
+++ b/tools/perf/ui/browser.c
@@ -740,8 +740,6 @@ void ui_browser__init(void)
  {
          int i = 0;

-        perf_config(ui_browser__color_config, NULL);
-
          while (ui_browser__colorsets[i].name) {
                  struct ui_browser_colorset *c = 
&ui_browser__colorsets[i++];
                  sltt_set_color(c->colorset, c->name, c->fg, c->bg);

... (omitted)


Many sub-commands call perf_config() at builtin-report.c, ui/browser.c
and etc. So I think it is ambiguous to decide where 
perf_config_set__delete()
will be called instead of at run_builtin().

(If the config set's life cycle is the same as perf's ,
I would call perf_config_set__delete() at run_builtin()
because a sub-command is done)


2) If having the config set for perf's life,

we would add configuration features to TUI like TUI configuring options
for linux kernel compiling (e.g. make menuconfig) ?

Of course, we don't need to have the same function as make menuconfig
but IMHO, we could add similar way to menuconfig while perf is running.


How do you feel about these ?


Thanks, :)
Taeung

>
>> But we need to use the config set that already contains all config
>> key-value pairs to avoid this repetitive work reading the config files
>> in perf_config(). (the config set mean a global variable 'config_set')
>>
>> In other words, if new perf_config() is called,
>> only first time 'config_set' is initialized collecting all configs
>> from the config files and it work with perf_config_set__iter().
>> And free the config set after a sub-command work at run_builtin().
>>
>> If we do, 'config_set' can be reused wherever using perf_config()
>> and a feature of old perf_config() is the same as new perf_config() work
>> without the repetitive work that read the config files.
>>
>> Cc: Namhyung Kim <namhyung@...nel.org>
>> Cc: Jiri Olsa <jolsa@...hat.com>
>> Cc: Wang Nan <wangnan0@...wei.com>
>> Cc: Peter Zijlstra <peterz@...radead.org>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Masami Hiramatsu <mhiramat@...nel.org>
>> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
>> Signed-off-by: Taeung Song <treeze.taeung@...il.com>
>> ---
>>   tools/perf/builtin-config.c |  4 +++
>>   tools/perf/perf.c           |  1 +
>>   tools/perf/util/config.c    | 87 ++++++++++++++++++++++-----------------------
>>   tools/perf/util/config.h    |  1 +
>>   4 files changed, 48 insertions(+), 45 deletions(-)
>>
>> diff --git a/tools/perf/builtin-config.c b/tools/perf/builtin-config.c
>> index fe1b77f..cfd1036 100644
>> --- a/tools/perf/builtin-config.c
>> +++ b/tools/perf/builtin-config.c
>> @@ -80,6 +80,10 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
>>   	else if (use_user_config)
>>   		config_exclusive_filename = user_config;
>>
>> +	/*
>> +	 * At only 'config' sub-command, individually use the config set
>> +	 * because of reinitializing with options config file location.
>> +	 */
>>   	set = perf_config_set__new();
>>   	if (!set) {
>>   		ret = -1;
>> diff --git a/tools/perf/perf.c b/tools/perf/perf.c
>> index 15982ce..fe2ab7c 100644
>> --- a/tools/perf/perf.c> - Arnaldo
>> +++ b/tools/perf/perf.c
>> @@ -391,6 +391,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
>>
>>   	perf_env__set_cmdline(&perf_env, argc, argv);
>>   	status = p->fn(argc, argv, prefix);
>> +	perf_config_set__delete(config_set);
>>   	exit_browser(status);
>>   	perf_env__exit(&perf_env);
>>   	bpf__clear();
>> diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
>> index 31e09a4..72db134 100644
>> --- a/tools/perf/util/config.c
>> +++ b/tools/perf/util/config.c
>> @@ -28,6 +28,7 @@ static int config_linenr;
>>   static int config_file_eof;
>>
>>   const char *config_exclusive_filename;
>> +struct perf_config_set *config_set;
>>
>>   static int get_next_char(void)
>>   {
>> @@ -478,51 +479,6 @@ static int perf_config_global(void)
>>   	return !perf_env_bool("PERF_CONFIG_NOGLOBAL", 0);
>>   }
>>
>> -int perf_config(config_fn_t fn, void *data)
>> -{
>> -	int ret = -1;
>> -	const char *home = NULL;
>> -
>> -	/* Setting $PERF_CONFIG makes perf read _only_ the given config file. */
>> -	if (config_exclusive_filename)
>> -		return perf_config_from_file(fn, config_exclusive_filename, data);
>> -	if (perf_config_system() && !access(perf_etc_perfconfig(), R_OK)) {
>> -		if (perf_config_from_file(fn, perf_etc_perfconfig(), data) < 0)
>> -			goto out;
>> -	}
>> -
>> -	home = getenv("HOME");
>> -	if (perf_config_global() && home) {
>> -		char *user_config = strdup(mkpath("%s/.perfconfig", home));
>> -		struct stat st;
>> -
>> -		if (user_config == NULL) {
>> -			warning("Not enough memory to process %s/.perfconfig, "
>> -				"ignoring it.", home);
>> -			goto out;
>> -		}
>> -
>> -		if (stat(user_config, &st) < 0)
>> -			goto out_free;
>> -
>> -		if (st.st_uid && (st.st_uid != geteuid())) {
>> -			warning("File %s not owned by current user or root, "
>> -				"ignoring it.", user_config);
>> -			goto out_free;
>> -		}
>> -
>> -		if (!st.st_size)
>> -			goto out_free;
>> -
>> -		ret = perf_config_from_file(fn, user_config, data);
>> -
>> -out_free:
>> -		free(user_config);
>> -	}
>> -out:
>> -	return ret;
>> -}
>> -
>>   static struct perf_config_section *find_section(struct list_head *sections,
>>   						const char *section_name)
>>   {
>> @@ -706,6 +662,47 @@ struct perf_config_set *perf_config_set__new(void)
>>   	return set;
>>   }
>>
>> +static int perf_config_set__iter(struct perf_config_set *set, config_fn_t fn, void *data)
>> +{
>> +	struct perf_config_section *section;
>> +	struct perf_config_item *item;
>> +	struct list_head *sections;
>> +	char key[BUFSIZ];
>> +
>> +	if (set == NULL)
>> +		return -1;
>> +
>> +	sections = &set->sections;
>> +	if (list_empty(sections))
>> +		return -1;
>> +
>> +	list_for_each_entry(section, sections, node) {
>> +		list_for_each_entry(item, &section->items, node) {
>> +			char *value = item->value;
>> +
>> +			if (value) {
>> +				scnprintf(key, sizeof(key), "%s.%s",
>> +					  section->name, item->name);
>> +				if (fn(key, value, data) < 0) {
>> +					pr_err("Error: wrong config key-value pair %s=%s\n",
>> +					       key, value);
>> +					return -1;
>> +				}
>> +			}
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +int perf_config(config_fn_t fn, void *data)
>> +{
>> +	if (config_set == NULL)
>> +		config_set = perf_config_set__new();
>> +
>> +	return perf_config_set__iter(config_set, fn, data);
>> +}
>> +
>>   static void perf_config_item__delete(struct perf_config_item *item)
>>   {
>>   	zfree(&item->name);
>> diff --git a/tools/perf/util/config.h b/tools/perf/util/config.h
>> index 35ccddb..7cc4fea 100644
>> --- a/tools/perf/util/config.h
>> +++ b/tools/perf/util/config.h
>> @@ -21,6 +21,7 @@ struct perf_config_set {
>>   };
>>
>>   extern const char *config_exclusive_filename;
>> +extern struct perf_config_set *config_set;
>>
>>   typedef int (*config_fn_t)(const char *, const char *, void *);
>>   int perf_default_config(const char *, const char *, void *);
>> --
>> 2.5.0

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