[PATCH V3 4/6] perf tools: Add FIFO file names as alternative options to --control

Adrian Hunter
2020-09-02T10:58:19Z

Enable the --control option to accept file names as an alternative to
file descriptors.

Example:

$ mkfifo perf.control
$ mkfifo perf.ack
$ cat perf.ack &
[1] 6808
$ perf record --control fifo:perf.control,perf.ack -- sleep 300 &
[2] 6810
$ echo disable > perf.control
$ Events disabled
ack

$ echo enable > perf.control
$ Events enabled
ack

$ echo disable > perf.control
$ Events disabled
ack

$ kill %2
[ perf record: Woken up 4 times to write data ]
$ [ perf record: Captured and wrote 0.018 MB perf.data (7 samples) ]

[1]- Done cat perf.ack
[2]+ Terminated perf record --control fifo:perf.control,perf.ack -- sleep 300
$

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
---

Changes in V3:

Rename evlist__parse_control_names to evlist__parse_control_fifo
Explicitly initialize *ctl_fd_close = false

tools/perf/Documentation/perf-record.txt | 2 +
tools/perf/Documentation/perf-stat.txt | 2 +
tools/perf/builtin-record.c | 34 +++++++++++----
tools/perf/builtin-stat.c | 18 ++++++--
tools/perf/util/evlist.c | 55 +++++++++++++++++++++++-
tools/perf/util/evlist.h | 2 +-
tools/perf/util/record.h | 1 +
tools/perf/util/stat.h | 1 +
8 files changed, 101 insertions(+), 14 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 07c4734f1c7a..2ffc1196d2b8 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -627,7 +627,9 @@ option. The -e option and this one can be mixed and matched. Events
can be grouped using the {} notation.
endif::HAVE_LIBPFM[]

+--control=fifo:ctl-fifo[,ack-fifo]::
--control=fd:ctl-fd[,ack-fd]::
+ctl-fifo / ack-fifo are opened and used as ctl-fd / ack-fd as follows.
Listen on ctl-fd descriptor for command to control measurement ('enable': enable events,
'disable': disable events). Measurements can be started with events disabled using
--delay=-1 option. Optionally send control command completion ('ack\n') to ack-fd descriptor
diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 7fb7368cc2d9..d33ffd11bb85 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -176,7 +176,9 @@ with it. --append may be used here. Examples:
3>results perf stat --log-fd 3 -- $cmd
3>>results perf stat --log-fd 3 --append -- $cmd

+--control=fifo:ctl-fifo[,ack-fifo]::
--control=fd:ctl-fd[,ack-fd]::
+ctl-fifo / ack-fifo are opened and used as ctl-fd / ack-fd as follows.
Listen on ctl-fd descriptor for command to control measurement ('enable': enable events,
'disable': disable events). Measurements can be started with events disabled using
--delay=-1 option. Optionally send control command completion ('ack\n') to ack-fd descriptor
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index f2ab5bd7e2ba..117dd180f780 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -2236,7 +2236,17 @@ static int parse_control_option(const struct option *opt,
{
struct record_opts *opts = opt->value;

- return evlist__parse_control(str, &opts->ctl_fd, &opts->ctl_fd_ack);
+ return evlist__parse_control(str, &opts->ctl_fd, &opts->ctl_fd_ack, &opts->ctl_fd_close);
+}
+
+static void close_control_option(struct record_opts *opts)
+{
+ if (opts->ctl_fd_close) {
+ opts->ctl_fd_close = false;
+ close(opts->ctl_fd);
+ if (opts->ctl_fd_ack >= 0)
+ close(opts->ctl_fd_ack);
+ }
}

static void switch_output_size_warn(struct record *rec)
@@ -2578,9 +2588,10 @@ static struct option __record_options[] = {
"libpfm4 event selector. use 'perf list' to list available events",
parse_libpfm_events_option),
#endif
- OPT_CALLBACK(0, "control", &record.opts, "fd:ctl-fd[,ack-fd]",
+ OPT_CALLBACK(0, "control", &record.opts, "fd:ctl-fd[,ack-fd] or fifo:ctl-fifo[,ack-fifo]",
"Listen on ctl-fd descriptor for command to control measurement ('enable': enable events, 'disable': disable events).\n"
- "\t\t\t Optionally send control command completion ('ack\\n') to ack-fd descriptor.",
+ "\t\t\t Optionally send control command completion ('ack\\n') to ack-fd descriptor.\n"
+ "\t\t\t Alternatively, ctl-fifo / ack-fifo will be opened and used as ctl-fd / ack-fd.",
parse_control_option),
OPT_END()
};
@@ -2653,12 +2664,14 @@ int cmd_record(int argc, const char **argv)
!perf_can_record_switch_events()) {
ui__error("kernel does not support recording context switch events\n");
parse_options_usage(record_usage, record_options, "switch-events", 0);
- return -EINVAL;
+ err = -EINVAL;
+ goto out_opts;
}

if (switch_output_setup(rec)) {
parse_options_usage(record_usage, record_options, "switch-output", 0);
- return -EINVAL;
+ err = -EINVAL;
+ goto out_opts;
}

if (rec->switch_output.time) {
@@ -2669,8 +2682,10 @@ int cmd_record(int argc, const char **argv)
if (rec->switch_output.num_files) {
rec->switch_output.filenames = calloc(sizeof(char *),
rec->switch_output.num_files);
- if (!rec->switch_output.filenames)
- return -EINVAL;
+ if (!rec->switch_output.filenames) {
+ err = -EINVAL;
+ goto out_opts;
+ }
}

/*
@@ -2686,7 +2701,8 @@ int cmd_record(int argc, const char **argv)
rec->affinity_mask.bits = bitmap_alloc(rec->affinity_mask.nbits);
if (!rec->affinity_mask.bits) {
pr_err("Failed to allocate thread mask for %zd cpus\n", rec->affinity_mask.nbits);
- return -ENOMEM;
+ err = -ENOMEM;
+ goto out_opts;
}
pr_debug2("thread mask[%zd]: empty\n", rec->affinity_mask.nbits);
}
@@ -2817,6 +2833,8 @@ int cmd_record(int argc, const char **argv)
evlist__delete(rec->evlist);
symbol__exit();
auxtrace_record__free(rec->itr);
+out_opts:
+ close_control_option(&rec->opts);
return err;
}

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 12ce5cf2b10e..6170226d44f9 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1047,7 +1047,17 @@ static int parse_control_option(const struct option *opt,
{
struct perf_stat_config *config = opt->value;

- return evlist__parse_control(str, &config->ctl_fd, &config->ctl_fd_ack);
+ return evlist__parse_control(str, &config->ctl_fd, &config->ctl_fd_ack, &config->ctl_fd_close);
+}
+
+static void close_control_option(struct perf_stat_config *config)
+{
+ if (config->ctl_fd_close) {
+ config->ctl_fd_close = false;
+ close(config->ctl_fd);
+ if (config->ctl_fd_ack >= 0)
+ close(config->ctl_fd_ack);
+ }
}

static struct option stat_options[] = {
@@ -1151,9 +1161,10 @@ static struct option stat_options[] = {
"libpfm4 event selector. use 'perf list' to list available events",
parse_libpfm_events_option),
#endif
- OPT_CALLBACK(0, "control", &stat_config, "fd:ctl-fd[,ack-fd]",
+ OPT_CALLBACK(0, "control", &stat_config, "fd:ctl-fd[,ack-fd] or fifo:ctl-fifo[,ack-fifo]",
"Listen on ctl-fd descriptor for command to control measurement ('enable': enable events, 'disable': disable events).\n"
- "\t\t\t Optionally send control command completion ('ack\\n') to ack-fd descriptor.",
+ "\t\t\t Optionally send control command completion ('ack\\n') to ack-fd descriptor.\n"
+ "\t\t\t Alternatively, ctl-fifo / ack-fifo will be opened and used as ctl-fd / ack-fd.",
parse_control_option),
OPT_END()
};
@@ -2396,6 +2407,7 @@ int cmd_stat(int argc, const char **argv)

metricgroup__rblist_exit(&stat_config.metric_events);
runtime_stat_delete(&stat_config);
+ close_control_option(&stat_config);

return status;
}
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 47d1045a19af..00593e5f2a9d 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1727,12 +1727,63 @@ struct evsel *perf_evlist__reset_weak_group(struct evlist *evsel_list,
return leader;
}

-int evlist__parse_control(const char *str, int *ctl_fd, int *ctl_fd_ack)
+static int evlist__parse_control_fifo(const char *str, int *ctl_fd, int *ctl_fd_ack, bool *ctl_fd_close)
+{
+ char *s, *p;
+ int ret = 0, fd;
+
+ if (strncmp(str, "fifo:", 5))
+ return -EINVAL;
+
+ str += 5;
+ if (!*str || *str == ',')
+ return -EINVAL;
+
+ s = strdup(str);
+ if (!s)
+ return -ENOMEM;
+
+ p = strchr(s, ',');
+ if (p)
+ *p = '\0';
+
+ /*
+ * O_RDWR avoids POLLHUPs which is necessary to allow the other
+ * end of a FIFO to be repeatedly opened and closed.
+ */
+ fd = open(s, O_RDWR | O_NONBLOCK | O_CLOEXEC);
+ if (fd < 0) {
+ pr_err("Failed to open '%s'\n", s);
+ ret = -errno;
+ goto out_free;
+ }
+ *ctl_fd = fd;
+ *ctl_fd_close = true;
+
+ if (p && *++p) {
+ /* O_RDWR | O_NONBLOCK means the other end need not be open */
+ fd = open(p, O_RDWR | O_NONBLOCK | O_CLOEXEC);
+ if (fd < 0) {
+ pr_err("Failed to open '%s'\n", p);
+ ret = -errno;
+ goto out_free;
+ }
+ *ctl_fd_ack = fd;
+ }
+
+out_free:
+ free(s);
+ return ret;
+}
+
+int evlist__parse_control(const char *str, int *ctl_fd, int *ctl_fd_ack, bool *ctl_fd_close)
{
char *comma = NULL, *endptr = NULL;

+ *ctl_fd_close = false;
+
if (strncmp(str, "fd:", 3))
- return -EINVAL;
+ return evlist__parse_control_fifo(str, ctl_fd, ctl_fd_ack, ctl_fd_close);

*ctl_fd = strtoul(&str[3], &endptr, 0);
if (endptr == &str[3])
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index a5a5a07d5c55..a5678eb5ee60 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -373,7 +373,7 @@ enum evlist_ctl_cmd {
EVLIST_CTL_CMD_ACK
};

-int evlist__parse_control(const char *str, int *ctl_fd, int *ctl_fd_ack);
+int evlist__parse_control(const char *str, int *ctl_fd, int *ctl_fd_ack, bool *ctl_fd_close);
int evlist__initialize_ctlfd(struct evlist *evlist, int ctl_fd, int ctl_fd_ack);
int evlist__finalize_ctlfd(struct evlist *evlist);
bool evlist__ctlfd_initialized(struct evlist *evlist);
diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
index 03678ff25539..266760ac9143 100644
--- a/tools/perf/util/record.h
+++ b/tools/perf/util/record.h
@@ -73,6 +73,7 @@ struct record_opts {
unsigned int nr_threads_synthesize;
int ctl_fd;
int ctl_fd_ack;
+ bool ctl_fd_close;
};

extern const char * const *record_usage;
diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index f8778cffd941..65402e13b704 100644
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -135,6 +135,7 @@ struct perf_stat_config {
struct rblist metric_events;
int ctl_fd;
int ctl_fd_ack;
+ bool ctl_fd_close;
};

void perf_stat__set_big_num(int set);
--
2.17.1