RE: [RFC PATCH v17 3/8] perf stat: Fork and launch perf record when perf stat needs to get retire latency value for a metric.

[Wang, Weilin]

> -----Original Message-----
> From: Namhyung Kim <namhyung@xxxxxxxxxx>
> Sent: Wednesday, July 17, 2024 10:56 PM
> To: Wang, Weilin <weilin.wang@xxxxxxxxx>
> Cc: Ian Rogers <irogers@xxxxxxxxxx>; Arnaldo Carvalho de Melo
> <acme@xxxxxxxxxx>; Peter Zijlstra <peterz@xxxxxxxxxxxxx>; Ingo Molnar
> <mingo@xxxxxxxxxx>; Alexander Shishkin
> <alexander.shishkin@xxxxxxxxxxxxxxx>; Jiri Olsa <jolsa@xxxxxxxxxx>; Hunter,
> Adrian <adrian.hunter@xxxxxxxxx>; Kan Liang <kan.liang@xxxxxxxxxxxxxxx>;
> linux-perf-users@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Taylor, Perry
> <perry.taylor@xxxxxxxxx>; Alt, Samantha <samantha.alt@xxxxxxxxx>; Biggers,
> Caleb <caleb.biggers@xxxxxxxxx>
> Subject: Re: [RFC PATCH v17 3/8] perf stat: Fork and launch perf record when
> perf stat needs to get retire latency value for a metric.
> 
> On Fri, Jul 12, 2024 at 03:09:25PM -0400, weilin.wang@xxxxxxxxx wrote:
> > From: Weilin Wang <weilin.wang@xxxxxxxxx>
> >
> > When retire_latency value is used in a metric formula, evsel would fork a perf
> > record process with "-e" and "-W" options. Perf record will collect required
> > retire_latency values in parallel while perf stat is collecting counting values.
> >
> > At the point of time that perf stat stops counting, evsel would stop perf
> record
> > by sending sigterm signal to perf record process. Sampled data will be
> process
> > to get retire latency value. Another thread is required to synchronize
> between
> > perf stat and perf record when we pass data through pipe.
> >
> > Retire_latency evsel is not opened for perf stat so that there is no counter
> > wasted on it. This commit includes code suggested by Namhyung to adjust
> reading
> > size for groups that include retire_latency evsels.
> >
> > Signed-off-by: Weilin Wang <weilin.wang@xxxxxxxxx>
> > ---
> >  tools/perf/builtin-stat.c     |   4 +
> >  tools/perf/util/Build         |   1 +
> >  tools/perf/util/evlist.c      |   2 +
> >  tools/perf/util/evsel.c       |  66 +++++-
> >  tools/perf/util/intel-tpebs.c | 430
> ++++++++++++++++++++++++++++++++++
> >  tools/perf/util/intel-tpebs.h |  35 +++
> >  6 files changed, 536 insertions(+), 2 deletions(-)
> >  create mode 100644 tools/perf/util/intel-tpebs.c
> >  create mode 100644 tools/perf/util/intel-tpebs.h
> >
> > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > index 661832756a24..68125bd75b37 100644
> > --- a/tools/perf/builtin-stat.c
> > +++ b/tools/perf/builtin-stat.c
> > @@ -70,6 +70,7 @@
> >  #include "util/bpf_counter.h"
> >  #include "util/iostat.h"
> >  #include "util/util.h"
> > +#include "util/intel-tpebs.h"
> >  #include "asm/bug.h"
> >
> >  #include <linux/time64.h>
> > @@ -683,6 +684,9 @@ static enum counter_recovery
> stat_handle_error(struct evsel *counter)
> >
> >  	if (child_pid != -1)
> >  		kill(child_pid, SIGTERM);
> > +
> > +	tpebs_delete();
> > +
> >  	return COUNTER_FATAL;
> >  }
> >
> > diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> > index 0f18fe81ef0b..25cae5c613ad 100644
> > --- a/tools/perf/util/Build
> > +++ b/tools/perf/util/Build
> > @@ -154,6 +154,7 @@ perf-util-y += clockid.o
> >  perf-util-y += list_sort.o
> >  perf-util-y += mutex.o
> >  perf-util-y += sharded_mutex.o
> > +perf-util-$(CONFIG_X86_64) += intel-tpebs.o
> >
> >  perf-util-$(CONFIG_LIBBPF) += bpf_map.o
> >  perf-util-$(CONFIG_PERF_BPF_SKEL) += bpf_counter.o
> > diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> > index 3a719edafc7a..78ce80f227aa 100644
> > --- a/tools/perf/util/evlist.c
> > +++ b/tools/perf/util/evlist.c
> > @@ -33,6 +33,7 @@
> >  #include "util/bpf-filter.h"
> >  #include "util/stat.h"
> >  #include "util/util.h"
> > +#include "util/intel-tpebs.h"
> >  #include <signal.h>
> >  #include <unistd.h>
> >  #include <sched.h>
> > @@ -179,6 +180,7 @@ void evlist__delete(struct evlist *evlist)
> >  	if (evlist == NULL)
> >  		return;
> >
> > +	tpebs_delete();
> >  	evlist__free_stats(evlist);
> >  	evlist__munmap(evlist);
> >  	evlist__close(evlist);
> > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > index bc603193c477..1d000fa2c6cf 100644
> > --- a/tools/perf/util/evsel.c
> > +++ b/tools/perf/util/evsel.c
> > @@ -1554,6 +1554,60 @@ static void evsel__set_count(struct evsel
> *counter, int cpu_map_idx, int thread,
> >  	perf_counts__set_loaded(counter->counts, cpu_map_idx, thread,
> true);
> >  }
> >
> > +static bool evsel__group_has_tpebs(struct evsel *leader)
> > +{
> > +	struct evsel *evsel;
> > +
> > +	for_each_group_evsel(evsel, leader) {
> > +		if (evsel__is_retire_lat(evsel))
> > +			return true;
> > +	}
> > +	return false;
> > +}
> > +
> > +static u64 evsel__group_read_nr_members(struct evsel *leader)
> > +{
> > +	u64 nr = leader->core.nr_members;
> > +	struct evsel *evsel;
> > +
> > +	for_each_group_evsel(evsel, leader) {
> > +		if (evsel__is_retire_lat(evsel))
> > +			nr--;
> > +	}
> > +	return nr;
> > +}
> > +
> > +static u64 evsel__group_read_size(struct evsel *leader)
> > +{
> > +	u64 read_format = leader->core.attr.read_format;
> > +	int entry = sizeof(u64); /* value */
> > +	int size = 0;
> > +	int nr = 1;
> > +
> > +	if (!evsel__group_has_tpebs(leader))
> > +		return perf_evsel__read_size(&leader->core);
> > +
> > +	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
> > +		size += sizeof(u64);
> > +
> > +	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
> > +		size += sizeof(u64);
> > +
> > +	if (read_format & PERF_FORMAT_ID)
> > +		entry += sizeof(u64);
> > +
> > +	if (read_format & PERF_FORMAT_LOST)
> > +		entry += sizeof(u64);
> > +
> > +	if (read_format & PERF_FORMAT_GROUP) {
> > +		nr = evsel__group_read_nr_members(leader);
> > +		size += sizeof(u64);
> > +	}
> > +
> > +	size += entry * nr;
> > +	return size;
> > +}
> > +
> >  static int evsel__process_group_data(struct evsel *leader, int cpu_map_idx,
> int thread, u64 *data)
> >  {
> >  	u64 read_format = leader->core.attr.read_format;
> > @@ -1562,7 +1616,7 @@ static int evsel__process_group_data(struct evsel
> *leader, int cpu_map_idx, int
> >
> >  	nr = *data++;
> >
> > -	if (nr != (u64) leader->core.nr_members)
> > +	if (nr != evsel__group_read_nr_members(leader))
> >  		return -EINVAL;
> >
> >  	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
> > @@ -1592,7 +1646,7 @@ static int evsel__read_group(struct evsel *leader,
> int cpu_map_idx, int thread)
> >  {
> >  	struct perf_stat_evsel *ps = leader->stats;
> >  	u64 read_format = leader->core.attr.read_format;
> > -	int size = perf_evsel__read_size(&leader->core);
> > +	int size = evsel__group_read_size(leader);
> >  	u64 *data = ps->group_data;
> >
> >  	if (!(read_format & PERF_FORMAT_ID))
> > @@ -2200,6 +2254,9 @@ static int evsel__open_cpu(struct evsel *evsel,
> struct perf_cpu_map *cpus,
> >  		return 0;
> >  	}
> >
> > +	if (evsel__is_retire_lat(evsel))
> > +		return tpebs_start(evsel->evlist);
> > +
> >  	err = __evsel__prepare_open(evsel, cpus, threads);
> >  	if (err)
> >  		return err;
> > @@ -2392,6 +2449,8 @@ int evsel__open(struct evsel *evsel, struct
> perf_cpu_map *cpus,
> >
> >  void evsel__close(struct evsel *evsel)
> >  {
> > +	if (evsel__is_retire_lat(evsel))
> > +		tpebs_delete();
> >  	perf_evsel__close(&evsel->core);
> >  	perf_evsel__free_id(&evsel->core);
> >  }
> > @@ -3357,6 +3416,9 @@ static int store_evsel_ids(struct evsel *evsel,
> struct evlist *evlist)
> >  {
> >  	int cpu_map_idx, thread;
> >
> > +	if (evsel__is_retire_lat(evsel))
> > +		return 0;
> > +
> >  	for (cpu_map_idx = 0; cpu_map_idx < xyarray__max_x(evsel->core.fd);
> cpu_map_idx++) {
> >  		for (thread = 0; thread < xyarray__max_y(evsel->core.fd);
> >  		     thread++) {
> > diff --git a/tools/perf/util/intel-tpebs.c b/tools/perf/util/intel-tpebs.c
> > new file mode 100644
> > index 000000000000..6680ef887961
> > --- /dev/null
> > +++ b/tools/perf/util/intel-tpebs.c
> > @@ -0,0 +1,430 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * intel_tpebs.c: Intel TPEBS support
> > + */
> > +
> > +
> > +#include <sys/param.h>
> > +#include <subcmd/run-command.h>
> > +#include <thread.h>
> > +#include "intel-tpebs.h"
> > +#include <linux/list.h>
> > +#include <linux/zalloc.h>
> > +#include <linux/err.h>
> > +#include "sample.h"
> > +#include "debug.h"
> > +#include "evlist.h"
> > +#include "evsel.h"
> > +#include "session.h"
> > +#include "tool.h"
> > +#include "cpumap.h"
> > +#include "metricgroup.h"
> > +#include <sys/stat.h>
> > +#include <sys/file.h>
> > +#include <poll.h>
> > +#include <math.h>
> > +
> > +#define PERF_DATA		"-"
> > +
> > +bool tpebs_recording;
> > +static pid_t tpebs_pid = -1;
> > +static size_t tpebs_event_size;
> > +static LIST_HEAD(tpebs_results);
> > +static pthread_t tpebs_reader_thread;
> > +static struct child_process *tpebs_cmd;
> > +
> > +struct tpebs_retire_lat {
> > +	struct list_head nd;
> > +	/* Event name */
> > +	const char *name;
> > +	/* Event name with the TPEBS modifier R */
> > +	const char *tpebs_name;
> > +	/* Count of retire_latency values found in sample data */
> > +	size_t count;
> > +	/* Sum of all the retire_latency values in sample data */
> > +	int sum;
> > +	/* Average of retire_latency, val = sum / count */
> > +	double val;
> > +};
> > +
> > +static int get_perf_record_args(const char **record_argv, char buf[],
> > +				const char *cpumap_buf)
> > +{
> > +	struct tpebs_retire_lat *e;
> > +	int i = 0;
> > +
> > +	pr_debug("tpebs: Prepare perf record for retire_latency\n");
> > +
> > +	record_argv[i++] = "perf";
> > +	record_argv[i++] = "record";
> > +	record_argv[i++] = "-W";
> > +	record_argv[i++] = "--synth=no";
> > +	record_argv[i++] = buf;
> > +
> > +	if (!cpumap_buf) {
> > +		pr_err("tpebs: Require cpumap list to run sampling\n");
> > +		return -ECANCELED;
> > +	}
> > +	/* Use -C when cpumap_buf is not "-1" */
> > +	if (strcmp(cpumap_buf, "-1")) {
> > +		record_argv[i++] = "-C";
> > +		record_argv[i++] = cpumap_buf;
> > +	}
> > +
> > +	list_for_each_entry(e, &tpebs_results, nd) {
> > +		record_argv[i++] = "-e";
> > +		record_argv[i++] = e->name;
> > +	}
> > +
> > +	record_argv[i++] = "-o";
> > +	record_argv[i++] = PERF_DATA;
> > +
> > +	return 0;
> > +}
> > +
> > +static int prepare_run_command(const char **argv)
> > +{
> > +	tpebs_cmd = zalloc(sizeof(struct child_process));
> > +	if (!tpebs_cmd)
> > +		return -ENOMEM;
> > +	tpebs_cmd->argv = argv;
> > +	tpebs_cmd->out = -1;
> > +	return 0;
> > +}
> > +
> > +static int start_perf_record(int control_fd[], int ack_fd[],
> > +				const char *cpumap_buf)
> > +{
> > +	const char **record_argv;
> > +	int ret;
> > +	char buf[32];
> > +
> > +	scnprintf(buf, sizeof(buf), "--control=fd:%d,%d", control_fd[0],
> ack_fd[1]);
> > +
> > +	record_argv = calloc(12 + 2 * tpebs_event_size, sizeof(char *));
> > +	if (!record_argv)
> > +		return -ENOMEM;
> > +
> > +	ret = get_perf_record_args(record_argv, buf, cpumap_buf);
> > +	if (ret)
> > +		goto out;
> > +
> > +	ret = prepare_run_command(record_argv);
> > +	if (ret)
> > +		goto out;
> > +	ret = start_command(tpebs_cmd);
> > +out:
> > +	free(record_argv);
> > +	return ret;
> > +}
> > +
> > +static int process_sample_event(struct perf_tool *tool __maybe_unused,
> > +				union perf_event *event __maybe_unused,
> > +				struct perf_sample *sample,
> > +				struct evsel *evsel,
> > +				struct machine *machine __maybe_unused)
> > +{
> > +	int ret = 0;
> > +	const char *evname;
> > +	struct tpebs_retire_lat *t;
> > +
> > +	evname = evsel__name(evsel);
> > +
> > +	/*
> > +	 * Need to handle per core results? We are assuming average retire
> > +	 * latency value will be used. Save the number of samples and the sum
> of
> > +	 * retire latency value for each event.
> > +	 */
> > +	list_for_each_entry(t, &tpebs_results, nd) {
> > +		if (!strcmp(evname, t->name)) {
> > +			t->count += 1;
> > +			t->sum += sample->retire_lat;
> > +			t->val = (double) t->sum / t->count;
> > +			break;
> > +		}
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +static int process_feature_event(struct perf_session *session,
> > +				 union perf_event *event)
> > +{
> > +	if (event->feat.feat_id < HEADER_LAST_FEATURE)
> > +		return perf_event__process_feature(session, event);
> > +	return 0;
> > +}
> > +
> > +static void *__sample_reader(void *arg)
> > +{
> > +	struct child_process *child = arg;
> > +	struct perf_session *session;
> > +	struct perf_data data = {
> > +		.mode = PERF_DATA_MODE_READ,
> > +		.path = PERF_DATA,
> > +		.file.fd = child->out,
> > +	};
> > +	struct perf_tool tool = {
> > +		.sample = process_sample_event,
> > +		.feature = process_feature_event,
> > +		.attr = perf_event__process_attr,
> > +	};
> > +
> > +	session = perf_session__new(&data, &tool);
> > +	if (IS_ERR(session))
> > +		return NULL;
> > +	perf_session__process_events(session);
> > +	perf_session__delete(session);
> > +
> > +	return NULL;
> > +}
> > +
> > +/*
> > + * tpebs_stop - stop the sample data read thread and the perf record
> process.
> > + */
> > +static int tpebs_stop(void)
> > +{
> > +	int ret = 0;
> > +
> > +	/* Like tpebs_start, we should only run tpebs_end once. */
> > +	if (tpebs_pid != -1) {
> > +		kill(tpebs_cmd->pid, SIGTERM);
> > +		tpebs_pid = -1;
> > +		pthread_join(tpebs_reader_thread, NULL);
> > +		close(tpebs_cmd->out);
> > +		ret = finish_command(tpebs_cmd);
> > +		if (ret == -ERR_RUN_COMMAND_WAITPID_SIGNAL)
> > +			ret = 0;
> > +	}
> > +	return ret;
> > +}
> > +
> > +/*
> > + * tpebs_start - start tpebs execution.
> > + * @evsel_list: retire_latency evsels in this list will be selected and sampled
> > + * to get the average retire_latency value.
> > + *
> > + * This function will be called from evlist level later when evlist__open() is
> > + * called consistently.
> > + */
> > +int tpebs_start(struct evlist *evsel_list)
> > +{
> > +	int ret = 0;
> > +	struct evsel *evsel;
> > +	char cpumap_buf[50];
> > +
> > +	/*
> > +	 * We should only run tpebs_start when tpebs_recording is enabled.
> > +	 * And we should only run it once with all the required events.
> > +	 */
> > +	if (tpebs_pid != -1 || !tpebs_recording)
> > +		return 0;
> > +
> > +	cpu_map__snprint(evsel_list->core.user_requested_cpus,
> cpumap_buf, sizeof(cpumap_buf));
> > +	/*
> > +	 * Prepare perf record for sampling event retire_latency before fork
> and
> > +	 * prepare workload
> > +	 */
> > +	evlist__for_each_entry(evsel_list, evsel) {
> > +		int i;
> > +		char *name;
> > +		struct tpebs_retire_lat *new;
> > +
> > +		if (!evsel->retire_lat)
> > +			continue;
> > +
> > +		pr_debug("tpebs: Retire_latency of event %s is required\n",
> evsel->name);
> > +		for (i = strlen(evsel->name) - 1; i > 0; i--) {
> > +			if (evsel->name[i] == 'R')
> > +				break;
> > +		}
> > +		if (i <= 0 || evsel->name[i] != 'R') {
> > +			ret = -1;
> > +			goto err;
> > +		}
> > +
> > +		name = strdup(evsel->name);
> > +		if (!name) {
> > +			ret = -ENOMEM;
> > +			goto err;
> > +		}
> > +		name[i] = 'p';
> > +
> > +		new = zalloc(sizeof(*new));
> > +		if (!new) {
> > +			ret = -1;
> > +			zfree(name);
> > +			goto err;
> > +		}
> > +		new->name = name;
> > +		new->tpebs_name = evsel->name;
> > +		list_add_tail(&new->nd, &tpebs_results);
> > +		tpebs_event_size += 1;
> > +	}
> > +
> > +	if (tpebs_event_size > 0) {
> > +		struct pollfd pollfd = { .events = POLLIN, };
> > +		int control_fd[2], ack_fd[2], len;
> > +		char ack_buf[8];
> > +
> > +		/*Create control and ack fd for --control*/
> > +		if (pipe(control_fd) < 0) {
> > +			pr_err("tpebs: Failed to create control fifo");
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +		if (pipe(ack_fd) < 0) {
> > +			pr_err("tpebs: Failed to create control fifo");
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		ret = start_perf_record(control_fd, ack_fd, cpumap_buf);
> > +		if (ret)
> > +			goto out;
> > +		tpebs_pid = tpebs_cmd->pid;
> > +		if (pthread_create(&tpebs_reader_thread, NULL,
> __sample_reader, tpebs_cmd)) {
> > +			kill(tpebs_cmd->pid, SIGTERM);
> > +			close(tpebs_cmd->out);
> > +			pr_err("Could not create thread to process sample
> data.\n");
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +		/* Wait for perf record initialization.*/
> > +		len = strlen("enable");
> > +		ret = write(control_fd[1], "enable", len);
> 
> Can we use EVLIST_CTL_CMD_ENABLE_TAG instead?
> 
> 
> > +		if (ret != len) {
> > +			pr_err("perf record control write control message
> failed\n");
> > +			goto out;
> > +		}
> > +
> > +		/* wait for an ack */
> > +		pollfd.fd = ack_fd[0];
> > +
> > +		/*
> > +		 * We need this poll to ensure the ack_fd PIPE will not hang
> > +		 * when perf record failed for any reason. The timeout value
> > +		 * 3000ms is an empirical selection.
> > +		 */
> 
> Oh, you changed it to 3 sec.  But I think it's ok as we don't wait for
> that long for the normal cases.

Hi Namhyung, 

I found it's more reliable to use 3 secs because in some of my test cases 2 secs 
are not enough for perf record reach the point of sending ACK back. 

Thanks,
Weilin

> 
> 
> > +		if (!poll(&pollfd, 1, 3000)) {
> > +			pr_err("tpebs failed: perf record ack timeout\n");
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		if (!(pollfd.revents & POLLIN)) {
> > +			pr_err("tpebs failed: did not received an ack\n");
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		ret = read(ack_fd[0], ack_buf, sizeof(ack_buf));
> > +		if (ret > 0)
> > +			ret = strcmp(ack_buf, "ack\n");
> 
> Same for EVLIST_CTL_CMD_ACK_TAG.
> 
> 
> > +		else {
> > +			pr_err("tpebs: perf record control ack failed\n");
> > +			goto out;
> > +		}
> > +out:
> > +		close(control_fd[0]);
> > +		close(control_fd[1]);
> > +		close(ack_fd[0]);
> > +		close(ack_fd[1]);
> > +	}
> > +err:
> > +	if (ret)
> > +		tpebs_delete();
> > +	return ret;
> > +}
> > +
> > +
> > +int tpebs_set_evsel(struct evsel *evsel, int cpu_map_idx, int thread)
> > +{
> > +	__u64 val;
> > +	bool found = false;
> > +	struct tpebs_retire_lat *t;
> > +	struct perf_counts_values *count;
> > +
> > +	/* Non reitre_latency evsel should never enter this function. */
> > +	if (!evsel__is_retire_lat(evsel))
> > +		return -1;
> > +
> > +	/*
> > +	 * Need to stop the forked record to ensure get sampled data from the
> > +	 * PIPE to process and get non-zero retire_lat value for hybrid.
> > +	 */
> > +	tpebs_stop();
> > +	count = perf_counts(evsel->counts, cpu_map_idx, thread);
> > +
> > +	list_for_each_entry(t, &tpebs_results, nd) {
> > +		if (t->tpebs_name == evsel->name || (evsel->metric_id
> && !strcmp(t->tpebs_name, evsel->metric_id))) {
> 
> This line is too long, please break.
> 
> Thanks,
> Namhyung
> 
> 
> > +			found = true;
> > +			break;
> > +		}
> > +	}
> > +
> > +	/* Set ena and run to non-zero */
> > +	count->ena = count->run = 1;
> > +	count->lost = 0;
> > +
> > +	if (!found) {
> > +		/*
> > +		 * Set default value or 0 when retire_latency for this event is
> > +		 * not found from sampling data (record_tpebs not set or 0
> > +		 * sample recorded).
> > +		 */
> > +		count->val = 0;
> > +		return 0;
> > +	}
> > +
> > +	/*
> > +	 * Only set retire_latency value to the first CPU and thread.
> > +	 */
> > +	if (cpu_map_idx == 0 && thread == 0)
> > +		val = rint(t->val);
> > +	else
> > +		val = 0;
> > +
> > +	count->val = val;
> > +	return 0;
> > +}
> > +
> > +static void tpebs_retire_lat__delete(struct tpebs_retire_lat *r)
> > +{
> > +	zfree(&r->name);
> > +	free(r);
> > +}
> > +
> > +
> > +/*
> > + * tpebs_delete - delete tpebs related data and stop the created thread and
> > + * process by calling tpebs_stop().
> > + *
> > + * This function is called from evlist_delete() and also from builtin-stat
> > + * stat_handle_error(). If tpebs_start() is called from places other then perf
> > + * stat, need to ensure tpebs_delete() is also called to safely free mem and
> > + * close the data read thread and the forked perf record process.
> > + *
> > + * This function is also called in evsel__close() to be symmetric with
> > + * tpebs_start() being called in evsel__open(). We will update this call site
> > + * when move tpebs_start() to evlist level.
> > + */
> > +void tpebs_delete(void)
> > +{
> > +	struct tpebs_retire_lat *r, *rtmp;
> > +
> > +	if (tpebs_pid == -1)
> > +		return;
> > +
> > +	tpebs_stop();
> > +
> > +	list_for_each_entry_safe(r, rtmp, &tpebs_results, nd) {
> > +		list_del_init(&r->nd);
> > +		tpebs_retire_lat__delete(r);
> > +	}
> > +
> > +	if (tpebs_cmd) {
> > +		free(tpebs_cmd);
> > +		tpebs_cmd = NULL;
> > +	}
> > +}
> > diff --git a/tools/perf/util/intel-tpebs.h b/tools/perf/util/intel-tpebs.h
> > new file mode 100644
> > index 000000000000..766b3fbd79f1
> > --- /dev/null
> > +++ b/tools/perf/util/intel-tpebs.h
> > @@ -0,0 +1,35 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * intel_tpebs.h: Intel TEPBS support
> > + */
> > +#ifndef INCLUDE__PERF_INTEL_TPEBS_H__
> > +#define INCLUDE__PERF_INTEL_TPEBS_H__
> > +
> > +#include "stat.h"
> > +#include "evsel.h"
> > +
> > +#ifdef HAVE_ARCH_X86_64_SUPPORT
> > +
> > +extern bool tpebs_recording;
> > +int tpebs_start(struct evlist *evsel_list);
> > +void tpebs_delete(void);
> > +int tpebs_set_evsel(struct evsel *evsel, int cpu_map_idx, int thread);
> > +
> > +#else
> > +
> > +static inline int tpebs_start(struct evlist *evsel_list __maybe_unused)
> > +{
> > +	return 0;
> > +}
> > +
> > +static inline void tpebs_delete(void) {};
> > +
> > +static inline int tpebs_set_evsel(struct evsel *evsel  __maybe_unused,
> > +				int cpu_map_idx  __maybe_unused,
> > +				int thread  __maybe_unused)
> > +{
> > +	return 0;
> > +}
> > +
> > +#endif
> > +#endif
> > --
> > 2.43.0
> >