Commit 6d499a6b authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
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perf lock: Print the number of lost entries for BPF 



Like the normal 'perf lock contention' output, it'd print the number of
lost entries for BPF if exists or -v option is passed.

Currently it uses BROKEN_CONTENDED stat for the lost count (due to full
stack maps).

  $ sudo perf lock con -a -b --map-nr-entries 128 sleep 5
  ...
  === output for debug===

  bad: 43, total: 14903
  bad rate: 0.29 %
  histogram of events caused bad sequence
      acquire: 0
     acquired: 0
    contended: 43
      release: 0

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Blake Jones <blakejones@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220802191004.347740-3-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent ceb13bfc

tools/perf/builtin-lock.c

+7 −1
Original line number Diff line number Diff line
@@ -1472,8 +1472,11 @@ static void print_contention_result(void) 
		pr_info("  %10s   %s\n\n", "type", "caller");



	bad = total = 0;

	if (use_bpf)

		bad = bad_hist[BROKEN_CONTENDED];



	while ((st = pop_from_result())) {

		total++;

		total += use_bpf ? st->nr_contended : 1;

		if (st->broken)

			bad++;
@@ -1687,6 +1690,9 @@ static int __cmd_contention(int argc, const char **argv) 


		lock_contention_stop();

		lock_contention_read(&con);



		/* abuse bad hist stats for lost entries */

		bad_hist[BROKEN_CONTENDED] = con.lost;

	} else {

		err = perf_session__process_events(session);

		if (err)

tools/perf/util/bpf_lock_contention.c

+4 −2
Original line number Diff line number Diff line
@@ -16,7 +16,7 @@ static struct lock_contention_bpf *skel; 


/* should be same as bpf_skel/lock_contention.bpf.c */

struct lock_contention_key {

	u32 stack_id;

	s32 stack_id;

};



struct lock_contention_data {
@@ -110,7 +110,7 @@ int lock_contention_stop(void) 
int lock_contention_read(struct lock_contention *con)

{

	int fd, stack;

	u32 prev_key, key;

	s32 prev_key, key;

	struct lock_contention_data data;

	struct lock_stat *st;

	struct machine *machine = con->machine;
@@ -119,6 +119,8 @@ int lock_contention_read(struct lock_contention *con) 
	fd = bpf_map__fd(skel->maps.lock_stat);

	stack = bpf_map__fd(skel->maps.stacks);



	con->lost = skel->bss->lost;



	prev_key = 0;

	while (!bpf_map_get_next_key(fd, &prev_key, &key)) {

		struct map *kmap;

tools/perf/util/bpf_skel/lock_contention.bpf.c

+7 −2
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ 
#define MAX_ENTRIES  10240



struct contention_key {

	__u32 stack_id;

	__s32 stack_id;

};



struct contention_data {
@@ -27,7 +27,7 @@ struct tstamp_data { 
	__u64 timestamp;

	__u64 lock;

	__u32 flags;

	__u32 stack_id;

	__s32 stack_id;

};



/* callstack storage  */
@@ -73,6 +73,9 @@ int enabled; 
int has_cpu;

int has_task;



/* error stat */

unsigned long lost;



static inline int can_record(void)

{

	if (has_cpu) {
@@ -116,6 +119,8 @@ int contention_begin(u64 *ctx) 
	pelem->flags = (__u32)ctx[1];

	pelem->stack_id = bpf_get_stackid(ctx, &stacks, BPF_F_FAST_STACK_CMP);



	if (pelem->stack_id < 0)

		lost++;

	return 0;

}

tools/perf/util/lock-contention.h

+1 −0
Original line number Diff line number Diff line
@@ -113,6 +113,7 @@ struct lock_contention { 
	struct machine *machine;

	struct hlist_head *result;

	unsigned long map_nr_entries;

	unsigned long lost;

};



#ifdef HAVE_BPF_SKEL