linux-kernel - Re: [PATCH 03/10] perf record: Turns auxtrace_snapshot

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Date:	Wed, 13 Apr 2016 12:55:33 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Adrian Hunter <adrian.hunter@...el.com>
Cc:	Wang Nan <wangnan0@...wei.com>, linux-kernel@...r.kernel.org,
	pi3orama@....com, He Kuang <hekuang@...wei.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Zefan Li <lizefan@...wei.com>
Subject: Re: [PATCH 03/10] perf record: Turns auxtrace_snapshot_enable into 3
 states

Em Wed, Apr 13, 2016 at 08:21:06AM +0000, Wang Nan escreveu:
> auxtrace_snapshot_enable has only two states (0/1). Turns it into a
> triple states enum so SIGUSR2 handler can safely do other works without
> triggering auxtrace snapshot.

Adrian, can you take a look at this? Is it ok with you?

Thanks,

- Arnaldo
 
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> Signed-off-by: He Kuang <hekuang@...wei.com>
> Acked-by: Jiri Olsa <jolsa@...nel.org>
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Zefan Li <lizefan@...wei.com>
> Cc: pi3orama@....com
> ---
>  tools/perf/builtin-record.c | 59 +++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 49 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index eb6a199..480033f 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -125,7 +125,43 @@ out:
>  static volatile int done;
>  static volatile int signr = -1;
>  static volatile int child_finished;
> -static volatile int auxtrace_snapshot_enabled;
> +
> +static volatile enum {
> +	AUXTRACE_SNAPSHOT_OFF = -1,
> +	AUXTRACE_SNAPSHOT_DISABLED = 0,
> +	AUXTRACE_SNAPSHOT_ENABLED = 1,
> +} auxtrace_snapshot_state = AUXTRACE_SNAPSHOT_OFF;
> +
> +static inline void
> +auxtrace_snapshot_on(void)
> +{
> +	auxtrace_snapshot_state = AUXTRACE_SNAPSHOT_DISABLED;
> +}
> +
> +static inline void
> +auxtrace_snapshot_enable(void)
> +{
> +	if (auxtrace_snapshot_state == AUXTRACE_SNAPSHOT_OFF)
> +		return;
> +	auxtrace_snapshot_state = AUXTRACE_SNAPSHOT_ENABLED;
> +}
> +
> +static inline void
> +auxtrace_snapshot_disable(void)
> +{
> +	if (auxtrace_snapshot_state == AUXTRACE_SNAPSHOT_OFF)
> +		return;
> +	auxtrace_snapshot_state = AUXTRACE_SNAPSHOT_DISABLED;
> +}
> +
> +static inline bool
> +auxtrace_snapshot_is_enabled(void)
> +{
> +	if (auxtrace_snapshot_state == AUXTRACE_SNAPSHOT_OFF)
> +		return false;
> +	return auxtrace_snapshot_state == AUXTRACE_SNAPSHOT_ENABLED;
> +}
> +
>  static volatile int auxtrace_snapshot_err;
>  static volatile int auxtrace_record__snapshot_started;
>  
> @@ -249,7 +285,7 @@ static void record__read_auxtrace_snapshot(struct record *rec)
>  	} else {
>  		auxtrace_snapshot_err = auxtrace_record__snapshot_finish(rec->itr);
>  		if (!auxtrace_snapshot_err)
> -			auxtrace_snapshot_enabled = 1;
> +			auxtrace_snapshot_enable();
>  	}
>  }
>  
> @@ -615,10 +651,13 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>  	signal(SIGCHLD, sig_handler);
>  	signal(SIGINT, sig_handler);
>  	signal(SIGTERM, sig_handler);
> -	if (rec->opts.auxtrace_snapshot_mode)
> +
> +	if (rec->opts.auxtrace_snapshot_mode) {
>  		signal(SIGUSR2, snapshot_sig_handler);
> -	else
> +		auxtrace_snapshot_on();
> +	} else {
>  		signal(SIGUSR2, SIG_IGN);
> +	}
>  
>  	session = perf_session__new(file, false, tool);
>  	if (session == NULL) {
> @@ -744,12 +783,12 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>  		perf_evlist__enable(rec->evlist);
>  	}
>  
> -	auxtrace_snapshot_enabled = 1;
> +	auxtrace_snapshot_enable();
>  	for (;;) {
>  		unsigned long long hits = rec->samples;
>  
>  		if (record__mmap_read_all(rec) < 0) {
> -			auxtrace_snapshot_enabled = 0;
> +			auxtrace_snapshot_disable();
>  			err = -1;
>  			goto out_child;
>  		}
> @@ -787,12 +826,12 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>  		 * disable events in this case.
>  		 */
>  		if (done && !disabled && !target__none(&opts->target)) {
> -			auxtrace_snapshot_enabled = 0;
> +			auxtrace_snapshot_disable();
>  			perf_evlist__disable(rec->evlist);
>  			disabled = true;
>  		}
>  	}
> -	auxtrace_snapshot_enabled = 0;
> +	auxtrace_snapshot_disable();
>  
>  	if (forks && workload_exec_errno) {
>  		char msg[STRERR_BUFSIZE];
> @@ -1358,9 +1397,9 @@ out_symbol_exit:
>  
>  static void snapshot_sig_handler(int sig __maybe_unused)
>  {
> -	if (!auxtrace_snapshot_enabled)
> +	if (!auxtrace_snapshot_is_enabled())
>  		return;
> -	auxtrace_snapshot_enabled = 0;
> +	auxtrace_snapshot_disable();
>  	auxtrace_snapshot_err = auxtrace_record__snapshot_start(record.itr);
>  	auxtrace_record__snapshot_started = 1;
>  }
> -- 
> 1.8.3.4