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Date: Tue, 19 Jan 2021 13:08:17 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: Jiri Olsa <jolsa@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
lkml <linux-kernel@...r.kernel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Ingo Molnar <mingo@...nel.org>,
Mark Rutland <mark.rutland@....com>,
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: Re: [PATCH 07/22] perf daemon: Add daemon command
Hi Jiri,
On Sun, Jan 3, 2021 at 7:05 AM Jiri Olsa <jolsa@...nel.org> wrote:
>
> Adding daemon command that allows to run record sessions
> on background. Each session represents one perf record
> process and is configured in config file.
>
> Example:
>
> # cat ~/.perfconfig
> [daemon]
> base=/opt/perfdata
>
> [session-cycles]
> run = -m 10M -e cycles --overwrite --switch-output -a
>
> [session-sched]
> run = -m 20M -e sched:* --overwrite --switch-output -a
>
> Starting the daemon:
>
> # perf daemon start
>
> Check sessions:
>
> # perf daemon
> [771394:daemon] base: /opt/perfdata
> [771395:cycles] perf record -m 10M -e cycles --overwrite --switch-output -a
> [771396:sched] perf record -m 20M -e sched:* --overwrite --switch-output -a
>
> Check sessions with more info:
>
> # perf daemon -v
> [771394:daemon] base: /opt/perfdata
> output: /opt/perfdata/output
> [771395:cycles] perf record -m 10M -e cycles --overwrite --switch-output -a
> base: /opt/perfdata/session-cycles
> output: /opt/perfdata/session-cycles/output
> [771396:sched] perf record -m 20M -e sched:* --overwrite --switch-output -a
> base: /opt/perfdata/session-sched
> output: /opt/perfdata/session-sched/output
>
> The 'output' file is perf record output for specific session.
>
> Note you have to stop all running perf processes manually at
> this point, stop command is coming in following patches.
>
> Adding empty perf-daemon.txt to skip compile warning,
> the man page is populated in following patch.
>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
[SNIP]
> +static int session_config(struct daemon *daemon, const char *var, const char *value)
> +{
> + struct session *session;
> + char name[100];
> +
> + if (get_session_name(var, name, sizeof(name)))
> + return -EINVAL;
> +
> + var = strchr(var, '.');
> + if (!var)
> + return -EINVAL;
> +
> + var++;
> +
> + session = daemon__find_session(daemon, name);
> + if (!session) {
> + session = daemon__add_session(daemon, name);
> + if (!session)
> + return -ENOMEM;
> +
> + pr_debug("reconfig: found new session %s\n", name);
> + /* This is new session, trigger reconfig to start it. */
> + session->state = SESSION_STATE__RECONFIG;
> + } else if (session->state == SESSION_STATE__KILL) {
> + /*
> + * The session was marked to kill and we still
> + * found it in config file.
> + */
> + pr_debug("reconfig: found current session %s\n", name);
> + session->state = SESSION_STATE__OK;
> + }
> +
> + if (!strcmp(var, "run")) {
> + if (session->run && strcmp(session->run, value)) {
> + free(session->run);
> + pr_debug("reconfig: session %s is changed\n", name);
> + session->state = SESSION_STATE__RECONFIG;
> + }
> + session->run = strdup(value);
Please check the result.
> + }
> +
> + return 0;
> +}
> +
> +static int server_config(const char *var, const char *value, void *cb)
> +{
> + struct daemon *daemon = cb;
> +
> + if (strstarts(var, "session-"))
> + return session_config(daemon, var, value);
> + else if (!strcmp(var, "daemon.base"))
> + daemon->base = strdup(value);
It seems these config items are mandatory. Is there a check
for their presence?
> +
> + return 0;
> +}
> +
> +static int client_config(const char *var, const char *value, void *cb)
> +{
> + struct daemon *daemon = cb;
> +
> + if (!strcmp(var, "daemon.base"))
> + daemon->base = strdup(value);
> +
> + return 0;
> +}
> +
> +static int setup_client_config(struct daemon *daemon)
> +{
> + struct perf_config_set *set;
> + int err = -ENOMEM;
> +
> + set = perf_config_set__load_file(daemon->config_real);
> + if (set) {
> + err = perf_config_set(set, client_config, daemon);
> + perf_config_set__delete(set);
> + }
> +
> + return err;
> +}
> +
> +static int setup_server_config(struct daemon *daemon)
> +{
> + struct perf_config_set *set;
> + struct session *session;
> + int err = -ENOMEM;
> +
> + pr_debug("reconfig: started\n");
> +
> + /*
> + * Mark all session for kill, the server config will
> + * set proper state for found sessions.
> + */
> + list_for_each_entry(session, &daemon->sessions, list)
> + session->state = SESSION_STATE__KILL;
Probably we can put them in a different state like INIT or READY?
> +
> + set = perf_config_set__load_file(daemon->config_real);
> + if (set) {
> + err = perf_config_set(set, server_config, daemon);
> + perf_config_set__delete(set);
> + }
> +
> + return err;
> +}
> +
> +static int session__signal(struct session *session, int sig)
> +{
> + if (session->pid < 0)
> + return -1;
> + return kill(session->pid, sig);
> +}
> +
> +static int session__run(struct session *session, struct daemon *daemon)
> +{
> + char buf[PATH_MAX];
> + char **argv;
> + int argc, fd;
> +
> + if (asprintf(&session->base, "%s/session-%s",
> + daemon->base, session->name) < 0) {
> + perror("asprintf failed");
> + return -1;
> + }
> +
> + if (mkdir(session->base, 0755) && errno != EEXIST) {
> + perror("mkdir failed");
> + return -1;
> + }
> +
> + session->pid = fork();
> + if (session->pid < 0)
> + return -1;
> + if (session->pid > 0) {
> + pr_info("reconfig: ruining session [%s:%d]: %s\n",
> + session->name, session->pid, session->run);
> + return 0;
> + }
> +
> + if (chdir(session->base)) {
> + perror("chdir failed");
> + return -1;
> + }
> +
> + fd = open("/dev/null", O_RDONLY);
> + if (fd < 0) {
> + perror("failed to open /dev/null");
> + return -1;
> + }
> +
> + close(0);
> + dup2(fd, 0);
The man page says dup2() will close the second file descriptor.
> + close(fd);
> +
> + fd = open(SESSION_OUTPUT, O_RDWR|O_CREAT|O_TRUNC, 0644);
> + if (fd < 0) {
> + perror("failed to open session output");
> + return -1;
> + }
> +
> + close(1);
> + close(2);
> + dup2(fd, 1);
> + dup2(fd, 2);
Ditto.
> + close(fd);
> +
> + scnprintf(buf, sizeof(buf), "%s record %s", daemon->perf, session->run);
> +
> + argv = argv_split(buf, &argc);
> + if (!argv)
> + exit(-1);
> +
> + exit(execve(daemon->perf, argv, NULL));
> + return -1;
> +}
[SNIP]
> +static int daemon__reconfig(struct daemon *daemon)
> +{
> + struct session *session, *n;
> +
> + list_for_each_entry_safe(session, n, &daemon->sessions, list) {
> + /* No change. */
> + if (session->state == SESSION_STATE__OK)
> + continue;
> +
> + /* Remove session. */
> + if (session->state == SESSION_STATE__KILL) {
> + if (session->pid > 0) {
> + session__kill(session);
> + pr_info("reconfig: session '%s' killed\n", session->name);
> + }
> + session__remove(session);
> + continue;
> + }
> +
> + /* Reconfig session. */
> + pr_debug2("reconfig: session '%s' start\n", session->name);
> + if (session->pid > 0) {
> + session__kill(session);
> + pr_info("reconfig: session '%s' killed\n", session->name);
> + }
> + if (session__run(session, daemon))
Does it call a config function? Or is it called already?
> + return -1;
> + pr_debug2("reconfig: session '%s' done\n", session->name);
> + session->state = SESSION_STATE__OK;
I think RUNNING is a better name.
Thanks,
Namhyung
> + }
> +
> + return 0;
> +}
> +
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