Re: [PATCH 2/4] perf lock contention: Use lock_stat_find{,new}

Arnaldo Carvalho de Melo
2023-02-02T20:27:59Z

Em Wed, Feb 01, 2023 at 09:04:53PM -0800, Namhyung Kim escreveu:
> This is a preparation work to support complex keys of BPF maps. Now it
> has single value key according to the aggregation mode like stack_id or
> pid. But we want to use a combination of those keys.
>
> Then lock_contention_read() should still aggregate the result based on
> the key that was requested by user. The other key info will be used for
> filtering.
>
> So instead of creating a lock_stat entry always, Check if it's already
> there using lock_stat_find() first.

Hey, try building without libtraceevent-devel installed, should be
equivalent to NO_LIBTRACEEVENT=1.

At this point I think you should move bpf_lock_contention.o to inside
that CONFIG_LIBTRACEEVENT if block.

perf-$(CONFIG_PERF_BPF_SKEL) += bpf_lock_contention.o

ifeq ($(CONFIG_LIBTRACEEVENT),y)
perf-$(CONFIG_PERF_BPF_SKEL) += bpf_kwork.o
endif

I'm removing this series from tmp.perf/core for now.

- Arnaldo

> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
> tools/perf/builtin-lock.c | 4 +--
> tools/perf/util/bpf_lock_contention.c | 41 ++++++++++++++++-----------
> tools/perf/util/lock-contention.h | 3 ++
> 3 files changed, 30 insertions(+), 18 deletions(-)
>
> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> index 216a9a252bf4..0593c6e636c6 100644
> --- a/tools/perf/builtin-lock.c
> +++ b/tools/perf/builtin-lock.c
> @@ -465,7 +465,7 @@ static struct lock_stat *pop_from_result(void)
> return container_of(node, struct lock_stat, rb);
> }
>
> -static struct lock_stat *lock_stat_find(u64 addr)
> +struct lock_stat *lock_stat_find(u64 addr)
> {
> struct hlist_head *entry = lockhashentry(addr);
> struct lock_stat *ret;
> @@ -477,7 +477,7 @@ static struct lock_stat *lock_stat_find(u64 addr)
> return NULL;
> }
>
> -static struct lock_stat *lock_stat_findnew(u64 addr, const char *name, int flags)
> +struct lock_stat *lock_stat_findnew(u64 addr, const char *name, int flags)
> {
> struct hlist_head *entry = lockhashentry(addr);
> struct lock_stat *ret, *new;
> diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
> index 967ce168f163..c6f2db603d5a 100644
> --- a/tools/perf/util/bpf_lock_contention.c
> +++ b/tools/perf/util/bpf_lock_contention.c
> @@ -254,12 +254,34 @@ int lock_contention_read(struct lock_contention *con)
> prev_key = NULL;
> while (!bpf_map_get_next_key(fd, prev_key, &key)) {
> s32 stack_id;
> + const char *name;
>
> /* to handle errors in the loop body */
> err = -1;
>
> bpf_map_lookup_elem(fd, &key, &data);
> - st = zalloc(sizeof(*st));
> +
> + if (con->save_callstack) {
> + stack_id = key.aggr_key;
> + bpf_map_lookup_elem(stack, &stack_id, stack_trace);
> + }
> +
> + st = lock_stat_find(key.aggr_key);
> + if (st != NULL) {
> + st->wait_time_total += data.total_time;
> + if (st->wait_time_max < data.max_time)
> + st->wait_time_max = data.max_time;
> + if (st->wait_time_min > data.min_time)
> + st->wait_time_min = data.min_time;
> +
> + st->nr_contended += data.count;
> + if (st->nr_contended)
> + st->avg_wait_time = st->wait_time_total / st->nr_contended;
> + goto next;
> + }
> +
> + name = lock_contention_get_name(con, &key, stack_trace);
> + st = lock_stat_findnew(key.aggr_key, name, data.flags);
> if (st == NULL)
> break;
>
> @@ -272,14 +294,6 @@ int lock_contention_read(struct lock_contention *con)
> st->avg_wait_time = data.total_time / data.count;
>
> st->flags = data.flags;
> - st->addr = key.aggr_key;
> -
> - stack_id = key.aggr_key;
> - bpf_map_lookup_elem(stack, &stack_id, stack_trace);
> -
> - st->name = strdup(lock_contention_get_name(con, &key, stack_trace));
> - if (st->name == NULL)
> - break;
>
> if (con->save_callstack) {
> st->callstack = memdup(stack_trace, stack_size);
> @@ -287,19 +301,14 @@ int lock_contention_read(struct lock_contention *con)
> break;
> }
>
> - hlist_add_head(&st->hash_entry, con->result);
> +next:
> prev_key = &key;
>
> - /* we're fine now, reset the values */
> - st = NULL;
> + /* we're fine now, reset the error */
> err = 0;
> }
>
> free(stack_trace);
> - if (st) {
> - free(st->name);
> - free(st);
> - }
>
> return err;
> }
> diff --git a/tools/perf/util/lock-contention.h b/tools/perf/util/lock-contention.h
> index 17e594d57a61..39d5bfc77f4e 100644
> --- a/tools/perf/util/lock-contention.h
> +++ b/tools/perf/util/lock-contention.h
> @@ -65,6 +65,9 @@ struct lock_stat {
> */
> #define MAX_LOCK_DEPTH 48
>
> +struct lock_stat *lock_stat_find(u64 addr);
> +struct lock_stat *lock_stat_findnew(u64 addr, const char *name, int flags);
> +
> /*
> * struct lock_seq_stat:
> * Place to put on state of one lock sequence
> --
> 2.39.1.456.gfc5497dd1b-goog
>

--

- Arnaldo