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perf lock: Print the number of lost entries for BPF

Browse source 
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: Namhyung 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: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Namhyung Kim 2022-08-02 12:10:04 -07:00 • committed by Arnaldo Carvalho de Melo
parent ceb13bfc01
commit 6d499a6b3d
4 changed files with 19 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
tools/perf/builtin-lock.c
View file

@ -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)

6
tools/perf/util/bpf_lock_contention.c
View file

@ -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;

9
tools/perf/util/bpf_skel/lock_contention.bpf.c
View file

@ -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;
}

1
tools/perf/util/lock-contention.h
View file

@ -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