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Message-Id: <20221209190727.759804-3-namhyung@kernel.org>
Date: Fri, 9 Dec 2022 11:07:25 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...nel.org>
Cc: Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
LKML <linux-kernel@...r.kernel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
linux-perf-users@...r.kernel.org, Song Liu <song@...nel.org>,
Blake Jones <blakejones@...gle.com>, bpf@...r.kernel.org
Subject: [PATCH 2/4] perf lock contention: Implement -t/--threads option for BPF
The BPF didn't show the per-thread stat properly. Use task's thread id (PID)
as a key instead of stack_id and add a task_data map to save task comm names.
$ sudo ./perf lock con -abt -E 5 sleep 1
contended total wait max wait avg wait pid comm
1 740.66 ms 740.66 ms 740.66 ms 1950 nv_queue
3 305.50 ms 298.19 ms 101.83 ms 1884 nvidia-modeset/
1 25.14 us 25.14 us 25.14 us 2725038 EventManager_De
12 23.09 us 9.30 us 1.92 us 0 swapper
1 20.18 us 20.18 us 20.18 us 2725033 EventManager_De
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
tools/perf/builtin-lock.c | 13 ++----
tools/perf/util/bpf_lock_contention.c | 40 ++++++++++++++++--
.../perf/util/bpf_skel/lock_contention.bpf.c | 41 +++++++++++++++++--
tools/perf/util/lock-contention.h | 1 +
4 files changed, 78 insertions(+), 17 deletions(-)
diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index 15ce6358f127..6fa3cdfec5cb 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -12,6 +12,7 @@
#include "util/target.h"
#include "util/callchain.h"
#include "util/lock-contention.h"
+#include "util/bpf_skel/lock_data.h"
#include <subcmd/pager.h>
#include <subcmd/parse-options.h>
@@ -61,11 +62,7 @@ static int max_stack_depth = CONTENTION_STACK_DEPTH;
static int stack_skip = CONTENTION_STACK_SKIP;
static int print_nr_entries = INT_MAX / 2;
-static enum {
- LOCK_AGGR_ADDR,
- LOCK_AGGR_TASK,
- LOCK_AGGR_CALLER,
-} aggr_mode = LOCK_AGGR_ADDR;
+static enum lock_aggr_mode aggr_mode = LOCK_AGGR_ADDR;
static struct thread_stat *thread_stat_find(u32 tid)
{
@@ -1619,6 +1616,7 @@ static int __cmd_contention(int argc, const char **argv)
.map_nr_entries = bpf_map_entries,
.max_stack = max_stack_depth,
.stack_skip = stack_skip,
+ .aggr_mode = show_thread_stats ? LOCK_AGGR_TASK : LOCK_AGGR_CALLER,
};
session = perf_session__new(use_bpf ? NULL : &data, &eops);
@@ -1691,11 +1689,6 @@ static int __cmd_contention(int argc, const char **argv)
if (select_key(true))
goto out_delete;
- if (show_thread_stats)
- aggr_mode = LOCK_AGGR_TASK;
- else
- aggr_mode = LOCK_AGGR_CALLER;
-
if (use_bpf) {
lock_contention_start();
if (argc)
diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index b6a8eb7164b3..1590a9f05145 100644
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -5,6 +5,7 @@
#include "util/map.h"
#include "util/symbol.h"
#include "util/target.h"
+#include "util/thread.h"
#include "util/thread_map.h"
#include "util/lock-contention.h"
#include <linux/zalloc.h>
@@ -30,10 +31,17 @@ int lock_contention_prepare(struct lock_contention *con)
}
bpf_map__set_value_size(skel->maps.stacks, con->max_stack * sizeof(u64));
- bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);
bpf_map__set_max_entries(skel->maps.lock_stat, con->map_nr_entries);
bpf_map__set_max_entries(skel->maps.tstamp, con->map_nr_entries);
+ if (con->aggr_mode == LOCK_AGGR_TASK) {
+ bpf_map__set_max_entries(skel->maps.task_data, con->map_nr_entries);
+ bpf_map__set_max_entries(skel->maps.stacks, 1);
+ } else {
+ bpf_map__set_max_entries(skel->maps.task_data, 1);
+ bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);
+ }
+
if (target__has_cpu(target))
ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
if (target__has_task(target))
@@ -82,7 +90,9 @@ int lock_contention_prepare(struct lock_contention *con)
bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
}
+ /* these don't work well if in the rodata section */
skel->bss->stack_skip = con->stack_skip;
+ skel->bss->aggr_mode = con->aggr_mode;
lock_contention_bpf__attach(skel);
return 0;
@@ -102,7 +112,7 @@ int lock_contention_stop(void)
int lock_contention_read(struct lock_contention *con)
{
- int fd, stack, err = 0;
+ int fd, stack, task_fd, err = 0;
struct contention_key *prev_key, key;
struct contention_data data = {};
struct lock_stat *st = NULL;
@@ -112,6 +122,7 @@ int lock_contention_read(struct lock_contention *con)
fd = bpf_map__fd(skel->maps.lock_stat);
stack = bpf_map__fd(skel->maps.stacks);
+ task_fd = bpf_map__fd(skel->maps.task_data);
con->lost = skel->bss->lost;
@@ -119,6 +130,13 @@ int lock_contention_read(struct lock_contention *con)
if (stack_trace == NULL)
return -1;
+ if (con->aggr_mode == LOCK_AGGR_TASK) {
+ struct thread *idle = __machine__findnew_thread(machine,
+ /*pid=*/0,
+ /*tid=*/0);
+ thread__set_comm(idle, "swapper", /*timestamp=*/0);
+ }
+
prev_key = NULL;
while (!bpf_map_get_next_key(fd, prev_key, &key)) {
struct map *kmap;
@@ -143,6 +161,22 @@ int lock_contention_read(struct lock_contention *con)
st->flags = data.flags;
+ if (con->aggr_mode == LOCK_AGGR_TASK) {
+ struct contention_task_data task;
+ struct thread *t;
+
+ st->addr = key.stack_or_task_id;
+
+ /* do not update idle comm which contains CPU number */
+ if (st->addr) {
+ bpf_map_lookup_elem(task_fd, &key, &task);
+ t = __machine__findnew_thread(machine, /*pid=*/-1,
+ key.stack_or_task_id);
+ thread__set_comm(t, task.comm, /*timestamp=*/0);
+ }
+ goto next;
+ }
+
bpf_map_lookup_elem(stack, &key, stack_trace);
/* skip lock internal functions */
@@ -175,7 +209,7 @@ int lock_contention_read(struct lock_contention *con)
if (st->callstack == NULL)
break;
}
-
+next:
hlist_add_head(&st->hash_entry, con->result);
prev_key = &key;
diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index 0f63cc28ccba..cd405adcd252 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -41,6 +41,13 @@ struct {
__uint(max_entries, MAX_ENTRIES);
} lock_stat SEC(".maps");
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(struct contention_task_data));
+ __uint(max_entries, MAX_ENTRIES);
+} task_data SEC(".maps");
+
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(key_size, sizeof(__u32));
@@ -61,6 +68,9 @@ int has_cpu;
int has_task;
int stack_skip;
+/* determine the key of lock stat */
+int aggr_mode;
+
/* error stat */
int lost;
@@ -87,6 +97,19 @@ static inline int can_record(void)
return 1;
}
+static inline void update_task_data(__u32 pid)
+{
+ struct contention_task_data *p;
+
+ p = bpf_map_lookup_elem(&task_data, &pid);
+ if (p == NULL) {
+ struct contention_task_data data;
+
+ bpf_get_current_comm(data.comm, sizeof(data.comm));
+ bpf_map_update_elem(&task_data, &pid, &data, BPF_NOEXIST);
+ }
+}
+
SEC("tp_btf/contention_begin")
int contention_begin(u64 *ctx)
{
@@ -115,10 +138,14 @@ int contention_begin(u64 *ctx)
pelem->timestamp = bpf_ktime_get_ns();
pelem->lock = (__u64)ctx[0];
pelem->flags = (__u32)ctx[1];
- pelem->stack_id = bpf_get_stackid(ctx, &stacks, BPF_F_FAST_STACK_CMP | stack_skip);
- if (pelem->stack_id < 0)
- lost++;
+ if (aggr_mode == LOCK_AGGR_CALLER) {
+ pelem->stack_id = bpf_get_stackid(ctx, &stacks,
+ BPF_F_FAST_STACK_CMP | stack_skip);
+ if (pelem->stack_id < 0)
+ lost++;
+ }
+
return 0;
}
@@ -141,7 +168,13 @@ int contention_end(u64 *ctx)
duration = bpf_ktime_get_ns() - pelem->timestamp;
- key.stack_id = pelem->stack_id;
+ if (aggr_mode == LOCK_AGGR_CALLER) {
+ key.stack_or_task_id = pelem->stack_id;
+ } else {
+ key.stack_or_task_id = pid;
+ update_task_data(pid);
+ }
+
data = bpf_map_lookup_elem(&lock_stat, &key);
if (!data) {
struct contention_data first = {
diff --git a/tools/perf/util/lock-contention.h b/tools/perf/util/lock-contention.h
index a2346875098d..47fd47fb56c1 100644
--- a/tools/perf/util/lock-contention.h
+++ b/tools/perf/util/lock-contention.h
@@ -117,6 +117,7 @@ struct lock_contention {
int lost;
int max_stack;
int stack_skip;
+ int aggr_mode;
};
#ifdef HAVE_BPF_SKEL
--
2.39.0.rc1.256.g54fd8350bd-goog
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