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Subject: [PATCH v9 10/15] perf stat: extend -D,--delay option with -1 value
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>
Cc:     Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Andi Kleen <ak@linux.intel.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
References: <a4d5db4a-f25c-38dc-1c41-321a886cb122@linux.intel.com>
Organization: Intel Corp.
Message-ID: <165b6d30-b038-1579-3f16-4ba780041179@linux.intel.com>
Date:   Fri, 3 Jul 2020 10:46:50 +0300
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Extend -D,--delay option with -1 value to start monitoring with
events disabled to be enabled later by enable command provided
via control file descriptor.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
 tools/perf/Documentation/perf-stat.txt |  5 +++--
 tools/perf/builtin-stat.c              | 18 ++++++++++++++----
 tools/perf/util/evlist.h               |  3 +++
 tools/perf/util/stat.h                 |  2 +-
 4 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index b029ee728a0b..9f32f6cd558d 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -238,8 +238,9 @@ mode, use --per-node in addition to -a. (system-wide).
 
 -D msecs::
 --delay msecs::
-After starting the program, wait msecs before measuring. This is useful to
-filter out the startup phase of the program, which is often very different.
+After starting the program, wait msecs before measuring (-1: start with events
+disabled). This is useful to filter out the startup phase of the program,
+which is often very different.
 
 -T::
 --transaction::
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 723f1fe27d63..9e4288ecf2b8 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -487,16 +487,26 @@ static bool handle_interval(unsigned int interval, int *times)
 
 static void enable_counters(void)
 {
-	if (stat_config.initial_delay)
+	if (stat_config.initial_delay < 0) {
+		pr_info(EVLIST_DISABLED_MSG);
+		return;
+	}
+
+	if (stat_config.initial_delay > 0) {
+		pr_info(EVLIST_DISABLED_MSG);
 		usleep(stat_config.initial_delay * USEC_PER_MSEC);
+	}
 
 	/*
 	 * We need to enable counters only if:
 	 * - we don't have tracee (attaching to task or cpu)
 	 * - we have initial delay configured
 	 */
-	if (!target__none(&target) || stat_config.initial_delay)
+	if (!target__none(&target) || stat_config.initial_delay) {
 		evlist__enable(evsel_list);
+		if (stat_config.initial_delay > 0)
+			pr_info(EVLIST_ENABLED_MSG);
+	}
 }
 
 static void disable_counters(void)
@@ -1056,8 +1066,8 @@ static struct option stat_options[] = {
 		     "aggregate counts per thread", AGGR_THREAD),
 	OPT_SET_UINT(0, "per-node", &stat_config.aggr_mode,
 		     "aggregate counts per numa node", AGGR_NODE),
-	OPT_UINTEGER('D', "delay", &stat_config.initial_delay,
-		     "ms to wait before starting measurement after program start"),
+	OPT_INTEGER('D', "delay", &stat_config.initial_delay,
+		    "ms to wait before starting measurement after program start (-1: start with events disabled)"),
 	OPT_CALLBACK_NOOPT(0, "metric-only", &stat_config.metric_only, NULL,
 			"Only print computed metrics. No raw values", enable_metric_only),
 	OPT_BOOLEAN(0, "metric-no-group", &stat_config.metric_no_group,
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 7e7abc621366..0728a4c35f7d 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -376,4 +376,7 @@ int evlist__initialize_ctlfd(struct evlist *evlist, int ctl_fd, int ctl_fd_ack);
 int evlist__finalize_ctlfd(struct evlist *evlist);
 int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd);
 
+#define EVLIST_ENABLED_MSG "Events enabled\n"
+#define EVLIST_DISABLED_MSG "Events disabled\n"
+
 #endif /* __PERF_EVLIST_H */
diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index 6911c7249199..41d59f192931 100644
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -116,7 +116,7 @@ struct perf_stat_config {
 	FILE			*output;
 	unsigned int		 interval;
 	unsigned int		 timeout;
-	unsigned int		 initial_delay;
+	int			 initial_delay;
 	unsigned int		 unit_width;
 	unsigned int		 metric_only_len;
 	int			 times;
-- 
2.24.1