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

From: Alexey Budankov
Date: Wed Sep 02 2020 - 13:03:58 EST

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In reply to: Adrian Hunter: "[PATCH V3 4/6] perf tools: Add FIFO file names as alternative options to --control"
Next in thread: Adrian Hunter: "Re: [PATCH V3 4/6] perf tools: Add FIFO file names as alternative options to --control"
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On 02.09.2020 13:57, Adrian Hunter wrote:
> 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@xxxxxxxxx>
> Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
>
>
> 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)

This function above and the same one for stat mode below look duplicating.
It could possibly be combined.

Acked-by: Alexei Budankov <alexey.budankov@xxxxxxxxxxxxxxx>

Regards,
Alexei

> +{
> + 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);
>

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