linux-kernel - [PATCH 4/4] perf tools: Add ping control command

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Message-Id: <20201226232038.390883-5-jolsa@kernel.org>
Date:   Sun, 27 Dec 2020 00:20:38 +0100
From:   Jiri Olsa <jolsa@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Ian Rogers <irogers@...gle.com>,
        Stephane Eranian <eranian@...gle.com>,
        Alexei Budankov <abudankov@...wei.com>
Subject: [PATCH 4/4] perf tools: Add ping control command

Adding control 'ping' command to detect if perf is up and
control interface is operational.

It will be used in following daemon patches to synchronize
with record session - when control interface is up and
running, we know that perf record is monitoring and ready
to receive signals.

Example session:

  terminal 1:
    # mkfifo control ack
    # perf record --control=fifo:control,ack

  terminal 2:
    # echo ping > control
    # cat ack
    ack

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 tools/perf/Documentation/perf-record.txt | 1 +
 tools/perf/builtin-record.c              | 1 +
 tools/perf/builtin-stat.c                | 1 +
 tools/perf/util/evlist.c                 | 4 ++++
 tools/perf/util/evlist.h                 | 2 ++
 5 files changed, 9 insertions(+)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 539230955dbc..aa2da60ff12b 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -646,6 +646,7 @@ Available commands:
   'disable name'     : disable event 'name'
   'snapshot'         : AUX area tracing snapshot).
   'stop'             : stop perf record
+  'ping'             : ping
 
   'evlist [-v|-g|-F] : display all events
                        -F  Show just the sample frequency used for each event.
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 9aa051c3c722..3de81453ff8a 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1949,6 +1949,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 			case EVLIST_CTL_CMD_ENABLE:
 			case EVLIST_CTL_CMD_DISABLE:
 			case EVLIST_CTL_CMD_EVLIST:
+			case EVLIST_CTL_CMD_PING:
 			default:
 				break;
 			}
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 5681cbabbec5..d5d08ffae31b 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -590,6 +590,7 @@ static void process_evlist(struct evlist *evlist, unsigned int interval)
 		case EVLIST_CTL_CMD_UNSUPPORTED:
 		case EVLIST_CTL_CMD_EVLIST:
 		case EVLIST_CTL_CMD_STOP:
+		case EVLIST_CTL_CMD_PING:
 		default:
 			break;
 		}
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index c6de70cefbae..61b2408821e5 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1943,6 +1943,9 @@ static int evlist__ctlfd_recv(struct evlist *evlist, enum evlist_ctl_cmd *cmd,
 		} else if (!strncmp(cmd_data, EVLIST_CTL_CMD_STOP_TAG,
 				    (sizeof(EVLIST_CTL_CMD_STOP_TAG)-1))) {
 			*cmd = EVLIST_CTL_CMD_STOP;
+		} else if (!strncmp(cmd_data, EVLIST_CTL_CMD_PING_TAG,
+				    (sizeof(EVLIST_CTL_CMD_PING_TAG)-1))) {
+			*cmd = EVLIST_CTL_CMD_PING;
 		}
 	}
 
@@ -2081,6 +2084,7 @@ int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd)
 				break;
 			case EVLIST_CTL_CMD_SNAPSHOT:
 			case EVLIST_CTL_CMD_STOP:
+			case EVLIST_CTL_CMD_PING:
 				break;
 			case EVLIST_CTL_CMD_ACK:
 			case EVLIST_CTL_CMD_UNSUPPORTED:
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 6f45c3630355..7c2521cb6b09 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -332,6 +332,7 @@ struct evsel *evlist__reset_weak_group(struct evlist *evlist, struct evsel *evse
 #define EVLIST_CTL_CMD_SNAPSHOT_TAG "snapshot"
 #define EVLIST_CTL_CMD_EVLIST_TAG "evlist"
 #define EVLIST_CTL_CMD_STOP_TAG "stop"
+#define EVLIST_CTL_CMD_PING_TAG "ping"
 
 #define EVLIST_CTL_CMD_MAX_LEN 64
 
@@ -343,6 +344,7 @@ enum evlist_ctl_cmd {
 	EVLIST_CTL_CMD_SNAPSHOT,
 	EVLIST_CTL_CMD_EVLIST,
 	EVLIST_CTL_CMD_STOP,
+	EVLIST_CTL_CMD_PING,
 };
 
 int evlist__parse_control(const char *str, int *ctl_fd, int *ctl_fd_ack, bool *ctl_fd_close);
-- 
2.26.2