Re: [PATCH 8/8] perf daemon: Set control fifo for session

From: Arnaldo Carvalho de Melo
Date: Tue Dec 15 2020 - 10:47:40 EST


Em Sat, Dec 12, 2020 at 11:43:58AM +0100, Jiri Olsa escreveu:
> Setup control fifos for session and add --control
> option to session arguments.

You're stating what this does, not why this is useful, can you add a
paragraph to that effect?

- Arnaldo

> Use can list control fifos with:
>
> # perf daemon -v
> [1:92187] perf record -m 11M -e cycles -o /opt/perfdata/1/perf.data --overwrite --switch-output -a
> output: /opt/perfdata/1/output
> control: /opt/perfdata/1/control
> ack: /opt/perfdata/1/ack
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> tools/perf/Documentation/perf-daemon.txt | 8 +++++++-
> tools/perf/builtin-daemon.c | 24 +++++++++++++++++++++++-
> 2 files changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-daemon.txt b/tools/perf/Documentation/perf-daemon.txt
> index 87de2c77e4c7..c507ba7c85cc 100644
> --- a/tools/perf/Documentation/perf-daemon.txt
> +++ b/tools/perf/Documentation/perf-daemon.txt
> @@ -16,7 +16,8 @@ DESCRIPTION
> This command allows to run simple daemon process that starts and
> monitors configured record sessions.
>
> -Each session represents one perf record process.
> +Each session represents one perf record process started with
> +control setup (with perf record --control.. options).
>
> These sessions are configured through config file, see CONFIG FILE
> section with EXAMPLES.
> @@ -94,10 +95,15 @@ Check sessions with more info:
> # perf daemon -v
> [1:92187] perf record -m 11M -e cycles -o /opt/perfdata/1/perf.data --overwrite --switch-output -a
> output: /opt/perfdata/1/output
> + control: /opt/perfdata/1/control
> + ack: /opt/perfdata/1/ack
> [2:92188] perf record -m 20M -e sched:* -o /opt/perfdata/2/perf.data --overwrite --switch-output -a
> output: /opt/perfdata/2/output
> + control: /opt/perfdata/2/control
> + ack: /opt/perfdata/2/ack
>
> The 'output' file is perf record output for specific session.
> +The 'control' and 'ack' files are perf control files.
>
>
> Send SIGUSR2 signal to all sessions:
> diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
> index 1bd5432a57a3..765369a30414 100644
> --- a/tools/perf/builtin-daemon.c
> +++ b/tools/perf/builtin-daemon.c
> @@ -33,6 +33,8 @@
> #include <api/fs/fs.h>
>
> #define SESSION_OUTPUT "output"
> +#define SESSION_CONTROL "control"
> +#define SESSION_ACK "ack"
>
> enum session_state {
> SESSION_STATE__OK,
> @@ -43,6 +45,7 @@ enum session_state {
> struct session {
> char *name;
> char *run;
> + char *control;
> int pid;
> struct list_head list;
> enum session_state state;
> @@ -254,6 +257,8 @@ static void session__kill(struct session *session, struct daemon *daemon)
>
> static int session__run(struct session *session, struct daemon *daemon)
> {
> + char control[PATH_MAX];
> + char ack[PATH_MAX];
> char base[PATH_MAX];
> char buf[PATH_MAX];
> char **argv;
> @@ -266,6 +271,18 @@ static int session__run(struct session *session, struct daemon *daemon)
> return -1;
> }
>
> + scnprintf(control, sizeof(control), "%s/" SESSION_CONTROL, base);
> + if (mkfifo(control, O_RDWR) && errno != EEXIST) {
> + perror("failed to create control fifo");
> + return -1;
> + }
> +
> + scnprintf(ack, sizeof(ack), "%s/" SESSION_ACK, base);
> + if (mkfifo(ack, O_RDWR) && errno != EEXIST) {
> + perror("failed to create ack fifo");
> + return -1;
> + }
> +
> session->pid = fork();
> if (session->pid < 0)
> return -1;
> @@ -291,7 +308,8 @@ static int session__run(struct session *session, struct daemon *daemon)
> dup2(fd, 2);
> close(fd);
>
> - scnprintf(buf, sizeof(buf), "%s record %s", PERF, session->run);
> + scnprintf(buf, sizeof(buf), "%s record --control=fifo:%s,%s %s",
> + PERF, control, ack, session->run);
>
> argv = argv_split(buf, &argc);
> if (!argv)
> @@ -472,6 +490,10 @@ static int cmd_session_list(struct daemon *daemon, FILE *out, bool simple)
> continue;
> fprintf(out, " output: %s/%s/" SESSION_OUTPUT "\n",
> daemon->base, session->name);
> + fprintf(out, " control: %s/%s/" SESSION_CONTROL "\n",
> + daemon->base, session->name);
> + fprintf(out, " ack: %s/%s/" SESSION_ACK "\n",
> + daemon->base, session->name);
> }
>
> return 0;
> --
> 2.26.2
>

--

- Arnaldo