perf tools: Add 'ping' control command

Add a control 'ping' command to detect if perf is up and its 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 <[email protected]> Tested-by: Arnaldo Carvalho de Melo <[email protected]> Acked-by: Namhyung Kim <[email protected]> Cc: Alexander Shishkin <[email protected]> Cc: Alexei Budankov <[email protected]> Cc: Ian Rogers <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Michael Petlan <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Link: http://lore.kernel.org/lkml/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
jangid · Jan 20, 2021 · 47fddcb · 47fddcb
1 parent f186cd6
commit 47fddcb
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diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
@@ -652,6 +652,7 @@ 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
@@ -1950,6 +1950,7 @@ 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
@@ -623,6 +623,7 @@ 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
@@ -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
@@ -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);