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

Namhyung Kim
2023-02-02T05:05:12Z

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.

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