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SubjectRe: [PATCH 3/3] perf lock: Print lost entries at the end
Em Tue, Aug 02, 2022 at 12:35:11AM -0700, Namhyung Kim escreveu:
> Like the normal perf lock report output, it'd print bad stats at the end
> if exists or -v option is passed. Currently it uses BROKEN_CONTENDED
stat for the lost count (due to full stack maps).

"Print the number of lost entries in verbose mode"?

> $ sudo perf lock con -a -b -m 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>
> ---
> tools/perf/builtin-lock.c | 8 +++++++-
> tools/perf/util/bpf_lock_contention.c | 6 ++++--
> tools/perf/util/bpf_skel/lock_contention.bpf.c | 9 +++++++--
> tools/perf/util/lock-contention.h | 1 +
> 4 files changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> index e32fdcd497e0..8065f0268e55 100644
> --- a/tools/perf/builtin-lock.c
> +++ b/tools/perf/builtin-lock.c
> @@ -1471,8 +1471,11 @@ 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++;
>
> @@ -1686,6 +1689,9 @@ 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)
> diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
> index 26128e5bb659..65f51cc25236 100644
> --- a/tools/perf/util/bpf_lock_contention.c
> +++ b/tools/perf/util/bpf_lock_contention.c
> @@ -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;
> diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> index 67d46533e518..9e8b94eb6320 100644
> --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> @@ -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;
> }
>
> diff --git a/tools/perf/util/lock-contention.h b/tools/perf/util/lock-contention.h
> index b09fd6eb978a..d9fc5f076567 100644
> --- a/tools/perf/util/lock-contention.h
> +++ b/tools/perf/util/lock-contention.h
> @@ -113,6 +113,7 @@ struct lock_contention {
> struct machine *machine;
> struct hlist_head *result;
> unsigned long map_len;
> + unsigned long lost;
> };
>
> #ifdef HAVE_BPF_SKEL
> --
> 2.37.1.455.g008518b4e5-goog

--

- Arnaldo

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