Commit 27c6f245 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

perf record: Record dropped sample count 



When it uses bpf filters, event might drop some samples.  It'd be nice
if it can report how many samples it lost.  As LOST_SAMPLES event can
carry the similar information, let's use it for bpf filters.

To indicate it's from BPF filters, add a new misc flag for that and
do not display cpu load warnings.

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Clark <james.clark@arm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Song Liu <song@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230314234237.3008956-2-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent d180aa56

tools/lib/perf/include/perf/event.h

+2 −0
Original line number Diff line number Diff line
@@ -70,6 +70,8 @@ struct perf_record_lost { 
	__u64			 lost;

};



#define PERF_RECORD_MISC_LOST_SAMPLES_BPF (1 << 15)



struct perf_record_lost_samples {

	struct perf_event_header header;

	__u64			 lost;

tools/perf/builtin-record.c

+24 −14
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ 
#include "util/pmu-hybrid.h"

#include "util/evlist-hybrid.h"

#include "util/off_cpu.h"

#include "util/bpf-filter.h"

#include "asm/bug.h"

#include "perf.h"

#include "cputopo.h"
@@ -1856,24 +1857,16 @@ record__switch_output(struct record *rec, bool at_exit) 
	return fd;

}



static void __record__read_lost_samples(struct record *rec, struct evsel *evsel,

static void __record__save_lost_samples(struct record *rec, struct evsel *evsel,

					struct perf_record_lost_samples *lost,

					int cpu_idx, int thread_idx)

					int cpu_idx, int thread_idx, u64 lost_count,

					u16 misc_flag)

{

	struct perf_counts_values count;

	struct perf_sample_id *sid;

	struct perf_sample sample = {};

	int id_hdr_size;



	if (perf_evsel__read(&evsel->core, cpu_idx, thread_idx, &count) < 0) {

		pr_debug("read LOST count failed\n");

		return;

	}



	if (count.lost == 0)

		return;



	lost->lost = count.lost;

	lost->lost = lost_count;

	if (evsel->core.ids) {

		sid = xyarray__entry(evsel->core.sample_id, cpu_idx, thread_idx);

		sample.id = sid->id;
@@ -1882,6 +1875,7 @@ static void __record__read_lost_samples(struct record *rec, struct evsel *evsel, 
	id_hdr_size = perf_event__synthesize_id_sample((void *)(lost + 1),

						       evsel->core.attr.sample_type, &sample);

	lost->header.size = sizeof(*lost) + id_hdr_size;

	lost->header.misc = misc_flag;

	record__write(rec, NULL, lost, lost->header.size);

}
@@ -1905,6 +1899,7 @@ static void record__read_lost_samples(struct record *rec) 


	evlist__for_each_entry(session->evlist, evsel) {

		struct xyarray *xy = evsel->core.sample_id;

		u64 lost_count;



		if (xy == NULL || evsel->core.fd == NULL)

			continue;
@@ -1916,12 +1911,27 @@ static void record__read_lost_samples(struct record *rec) 


		for (int x = 0; x < xyarray__max_x(xy); x++) {

			for (int y = 0; y < xyarray__max_y(xy); y++) {

				__record__read_lost_samples(rec, evsel, lost, x, y);

				struct perf_counts_values count;



				if (perf_evsel__read(&evsel->core, x, y, &count) < 0) {

					pr_debug("read LOST count failed\n");

					goto out;

				}



				if (count.lost) {

					__record__save_lost_samples(rec, evsel, lost,

								    x, y, count.lost, 0);

				}

			}

		}

	free(lost);



		lost_count = perf_bpf_filter__lost_count(evsel);

		if (lost_count)

			__record__save_lost_samples(rec, evsel, lost, 0, 0, lost_count,

						    PERF_RECORD_MISC_LOST_SAMPLES_BPF);

	}

out:

	free(lost);

}



static volatile sig_atomic_t workload_exec_errno;

tools/perf/util/bpf-filter.c

+7 −0
Original line number Diff line number Diff line
@@ -69,6 +69,13 @@ int perf_bpf_filter__destroy(struct evsel *evsel) 
	return 0;

}



u64 perf_bpf_filter__lost_count(struct evsel *evsel)

{

	struct sample_filter_bpf *skel = evsel->bpf_skel;



	return skel ? skel->bss->dropped : 0;

}



struct perf_bpf_filter_expr *perf_bpf_filter_expr__new(unsigned long sample_flags,

						       enum perf_bpf_filter_op op,

						       unsigned long val)

tools/perf/util/bpf-filter.h

+5 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ struct perf_bpf_filter_expr *perf_bpf_filter_expr__new(unsigned long sample_flag 
int perf_bpf_filter__parse(struct list_head *expr_head, const char *str);

int perf_bpf_filter__prepare(struct evsel *evsel);

int perf_bpf_filter__destroy(struct evsel *evsel);

u64 perf_bpf_filter__lost_count(struct evsel *evsel);



#else /* !HAVE_BPF_SKEL */
@@ -38,5 +39,9 @@ static inline int perf_bpf_filter__destroy(struct evsel *evsel __maybe_unused) 
{

	return -EOPNOTSUPP;

}

static inline u64 perf_bpf_filter__lost_count(struct evsel *evsel __maybe_unused)

{

	return 0;

}

#endif /* HAVE_BPF_SKEL*/

#endif /* PERF_UTIL_BPF_FILTER_H */

tools/perf/util/session.c

+2 −1
Original line number Diff line number Diff line
@@ -1582,7 +1582,8 @@ static int machines__deliver_event(struct machines *machines, 
			evlist->stats.total_lost += event->lost.lost;

		return tool->lost(tool, event, sample, machine);

	case PERF_RECORD_LOST_SAMPLES:

		if (tool->lost_samples == perf_event__process_lost_samples)

		if (tool->lost_samples == perf_event__process_lost_samples &&

		    !(event->header.misc & PERF_RECORD_MISC_LOST_SAMPLES_BPF))

			evlist->stats.total_lost_samples += event->lost_samples.lost;

		return tool->lost_samples(tool, event, sample, machine);

	case PERF_RECORD_READ: