[PATCH v2 0/3] perf lock contention: Improve aggr x filter combination

[PATCH v2 0/3] perf lock contention: Improve aggr x filter combination

[Namhyung Kim]

Hello,

The callstack filter can be useful to debug lock issues but it has a
limitation that it only works with caller aggregation mode (which is the
default setting).  IOW it cannot filter by callstack when showing tasks
or lock addresses/names.

But sometimes users want to use the filter for other aggregation mode.
Like "show me lock addresses/names from this caller only" or "show me
tasks having these callers".

When it's using tracepoint events from the data file, the situation is
good since the tracepoints have all the necessary info.  But when using
BPF it needs to extend the key of lock stat BPF map to have more than
one info like 'pid + stack_id' or 'lock_addr + stack_id'.  As callstack
filter works in userspace, it should save the both info.

With this change we can now use the -S/--callstack-filter with the
-t/--threads option or -l/--lock-addr option.  It's also possible to use
it with other filter options.

The following example shows the top 5 tasks that have contention
somewhere in the epoll handling.

  $ sudo perf lock con -abt -S epoll -E5 -- sleep 1
   contended   total wait     max wait     avg wait          pid   comm

           2     58.64 us     32.38 us     29.32 us      1514752   Chrome_IOThread
           3     29.31 us     12.65 us      9.77 us         3773   Xorg
           1     17.45 us     17.45 us     17.45 us      1514906   Chrome_ChildIOT
           1     15.41 us     15.41 us     15.41 us      1515382   Chrome_ChildIOT
           1     12.52 us     12.52 us     12.52 us       293878   IPC I/O Parent

You get get the code at 'perf/lock-filter-v1' branch in

  git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git

Thanks,
Namhyung

Namhyung Kim (3):
  perf lock contention: Factor out lock_contention_get_name()
  perf lock contention: Use lock_stat_find{,new}
  perf lock contention: Support filters for different aggregation

 tools/perf/builtin-lock.c                     |  79 ++++----
 tools/perf/util/Build                         |   5 +-
 tools/perf/util/bpf_lock_contention.c         | 180 +++++++++++-------
 .../perf/util/bpf_skel/lock_contention.bpf.c  |  15 +-
 tools/perf/util/bpf_skel/lock_data.h          |   4 +-
 tools/perf/util/lock-contention.h             |   5 +
 6 files changed, 178 insertions(+), 110 deletions(-)

-- 
2.39.1.519.gcb327c4b5f-goog

[PATCH v2 1/3] perf lock contention: Factor out lock_contention_get_name()

[Namhyung Kim]

The lock_contention_get_name() returns a name for the lock stat entry
based on the current aggregation mode.  As it's called sequentially in a
single thread, it can return the address of a static buffer for symbol
and offset of the caller.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/bpf_lock_contention.c | 115 +++++++++++++++-----------
 1 file changed, 65 insertions(+), 50 deletions(-)

diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index 4902ac331f41..286e52ba9f91 100644
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -163,9 +163,70 @@ int lock_contention_stop(void)
 	return 0;
 }
 
+static const char *lock_contention_get_name(struct lock_contention *con,
+					    struct contention_key *key,
+					    u64 *stack_trace)
+{
+	int idx = 0;
+	u64 addr;
+	const char *name = "";
+	static char name_buf[KSYM_NAME_LEN];
+	struct symbol *sym;
+	struct map *kmap;
+	struct machine *machine = con->machine;
+
+	if (con->aggr_mode == LOCK_AGGR_TASK) {
+		struct contention_task_data task;
+		int pid = key->aggr_key;
+		int task_fd = bpf_map__fd(skel->maps.task_data);
+
+		/* do not update idle comm which contains CPU number */
+		if (pid) {
+			struct thread *t = __machine__findnew_thread(machine, /*pid=*/-1, pid);
+
+			if (t == NULL)
+				return name;
+			if (!bpf_map_lookup_elem(task_fd, &pid, &task) &&
+			    thread__set_comm(t, task.comm, /*timestamp=*/0))
+				name = task.comm;
+		}
+		return name;
+	}
+
+	if (con->aggr_mode == LOCK_AGGR_ADDR) {
+		sym = machine__find_kernel_symbol(machine, key->aggr_key, &kmap);
+		if (sym)
+			name = sym->name;
+		return name;
+	}
+
+	/* LOCK_AGGR_CALLER: skip lock internal functions */
+	while (machine__is_lock_function(machine, stack_trace[idx]) &&
+	       idx < con->max_stack - 1)
+		idx++;
+
+	addr = stack_trace[idx];
+	sym = machine__find_kernel_symbol(machine, addr, &kmap);
+
+	if (sym) {
+		unsigned long offset;
+
+		offset = kmap->map_ip(kmap, addr) - sym->start;
+
+		if (offset == 0)
+			return sym->name;
+
+		snprintf(name_buf, sizeof(name_buf), "%s+%#lx", sym->name, offset);
+	} else {
+		snprintf(name_buf, sizeof(name_buf), "%#lx", (unsigned long)addr);
+	}
+
+	return name_buf;
+}
+
 int lock_contention_read(struct lock_contention *con)
 {
-	int fd, stack, task_fd, err = 0;
+	int fd, stack, err = 0;
 	struct contention_key *prev_key, key;
 	struct contention_data data = {};
 	struct lock_stat *st = NULL;
@@ -175,7 +236,6 @@ 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;
 
@@ -195,9 +255,6 @@ int lock_contention_read(struct lock_contention *con)
 
 	prev_key = NULL;
 	while (!bpf_map_get_next_key(fd, prev_key, &key)) {
-		struct map *kmap;
-		struct symbol *sym;
-		int idx = 0;
 		s32 stack_id;
 
 		/* to handle errors in the loop body */
@@ -219,61 +276,19 @@ int lock_contention_read(struct lock_contention *con)
 		st->flags = data.flags;
 		st->addr = key.aggr_key;
 
-		if (con->aggr_mode == LOCK_AGGR_TASK) {
-			struct contention_task_data task;
-			struct thread *t;
-			int pid = key.aggr_key;
-
-			/* do not update idle comm which contains CPU number */
-			if (st->addr) {
-				bpf_map_lookup_elem(task_fd, &pid, &task);
-				t = __machine__findnew_thread(machine, /*pid=*/-1, pid);
-				thread__set_comm(t, task.comm, /*timestamp=*/0);
-			}
-			goto next;
-		}
-
-		if (con->aggr_mode == LOCK_AGGR_ADDR) {
-			sym = machine__find_kernel_symbol(machine, st->addr, &kmap);
-			if (sym)
-				st->name = strdup(sym->name);
-			goto next;
-		}
-
 		stack_id = key.aggr_key;
 		bpf_map_lookup_elem(stack, &stack_id, stack_trace);
 
-		/* skip lock internal functions */
-		while (machine__is_lock_function(machine, stack_trace[idx]) &&
-		       idx < con->max_stack - 1)
-			idx++;
-
-		st->addr = stack_trace[idx];
-		sym = machine__find_kernel_symbol(machine, st->addr, &kmap);
-
-		if (sym) {
-			unsigned long offset;
-			int ret = 0;
-
-			offset = kmap->map_ip(kmap, st->addr) - sym->start;
-
-			if (offset)
-				ret = asprintf(&st->name, "%s+%#lx", sym->name, offset);
-			else
-				st->name = strdup(sym->name);
-
-			if (ret < 0 || st->name == NULL)
-				break;
-		} else if (asprintf(&st->name, "%#lx", (unsigned long)st->addr) < 0) {
+		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);
 			if (st->callstack == NULL)
 				break;
 		}
-next:
+
 		hlist_add_head(&st->hash_entry, con->result);
 		prev_key = &key;
 
-- 
2.39.1.519.gcb327c4b5f-goog

[PATCH v2 2/3] perf lock contention: Use lock_stat_find{,new}

[Namhyung Kim]

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/Build                 |  5 +++-
 tools/perf/util/bpf_lock_contention.c | 41 ++++++++++++++++-----------
 tools/perf/util/lock-contention.h     |  3 ++
 4 files changed, 34 insertions(+), 19 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/Build b/tools/perf/util/Build
index 79b9498886a2..918b501f9bd8 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -154,7 +154,10 @@ perf-$(CONFIG_PERF_BPF_SKEL) += bpf_counter.o
 perf-$(CONFIG_PERF_BPF_SKEL) += bpf_counter_cgroup.o
 perf-$(CONFIG_PERF_BPF_SKEL) += bpf_ftrace.o
 perf-$(CONFIG_PERF_BPF_SKEL) += bpf_off_cpu.o
-perf-$(CONFIG_PERF_BPF_SKEL) += bpf_lock_contention.o
+
+ifeq ($(CONFIG_LIBTRACEEVENT),y)
+  perf-$(CONFIG_PERF_BPF_SKEL) += bpf_lock_contention.o
+endif
 
 ifeq ($(CONFIG_LIBTRACEEVENT),y)
   perf-$(CONFIG_PERF_BPF_SKEL) += bpf_kwork.o
diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index 286e52ba9f91..ead2898ba377 100644
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -256,12 +256,34 @@ 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;
 
@@ -274,14 +296,6 @@ 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);
@@ -289,19 +303,14 @@ 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
-- 
2.39.1.519.gcb327c4b5f-goog

[PATCH v2 3/3] perf lock contention: Support filters for different aggregation

[Namhyung Kim]

It'd be useful to filter other than the current aggregation mode.  For
example, users may want to see callstacks for specific locks only.  Or
they may want tasks from a certain callstack.

The tracepoints already collected the information but it needs to check
the condition again when processing the event.  And it needs to change
BPF to allow the key combinations.

The lock contentions on 'rcu_state' spinlock can be monitored:

  $ sudo perf lock con -abv -L rcu_state sleep 1
  ...
   contended   total wait     max wait     avg wait         type   caller

           4    151.39 us     62.57 us     37.85 us     spinlock   rcu_core+0xcb
                          0xffffffff81fd1666  _raw_spin_lock_irqsave+0x46
                          0xffffffff8172d76b  rcu_core+0xcb
                          0xffffffff822000eb  __softirqentry_text_start+0xeb
                          0xffffffff816a0ba9  __irq_exit_rcu+0xc9
                          0xffffffff81fc0112  sysvec_apic_timer_interrupt+0xa2
                          0xffffffff82000e46  asm_sysvec_apic_timer_interrupt+0x16
                          0xffffffff81d49f78  cpuidle_enter_state+0xd8
                          0xffffffff81d4a259  cpuidle_enter+0x29
           1     30.21 us     30.21 us     30.21 us     spinlock   rcu_core+0xcb
                          0xffffffff81fd1666  _raw_spin_lock_irqsave+0x46
                          0xffffffff8172d76b  rcu_core+0xcb
                          0xffffffff822000eb  __softirqentry_text_start+0xeb
                          0xffffffff816a0ba9  __irq_exit_rcu+0xc9
                          0xffffffff81fc00c4  sysvec_apic_timer_interrupt+0x54
                          0xffffffff82000e46  asm_sysvec_apic_timer_interrupt+0x16
           1     28.84 us     28.84 us     28.84 us     spinlock   rcu_accelerate_cbs_unlocked+0x40
                          0xffffffff81fd1c60  _raw_spin_lock+0x30
                          0xffffffff81728cf0  rcu_accelerate_cbs_unlocked+0x40
                          0xffffffff8172da82  rcu_core+0x3e2
                          0xffffffff822000eb  __softirqentry_text_start+0xeb
                          0xffffffff816a0ba9  __irq_exit_rcu+0xc9
                          0xffffffff81fc0112  sysvec_apic_timer_interrupt+0xa2
                          0xffffffff82000e46  asm_sysvec_apic_timer_interrupt+0x16
                          0xffffffff81d49f78  cpuidle_enter_state+0xd8
  ...

To see tasks calling 'rcu_core' function:

  $ sudo perf lock con -abt -S rcu_core sleep 1
   contended   total wait     max wait     avg wait          pid   comm

          19     23.46 us      2.21 us      1.23 us            0   swapper
           2     18.37 us     17.01 us      9.19 us      2061859   ThreadPoolForeg
           3      5.76 us      1.97 us      1.92 us         3909   pipewire-pulse
           1      2.26 us      2.26 us      2.26 us      1809271   MediaSu~isor #2
           1      1.97 us      1.97 us      1.97 us      1514882   Chrome_ChildIOT
           1       987 ns       987 ns       987 ns         3740   pipewire-pulse

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/builtin-lock.c                     | 75 +++++++++++--------
 tools/perf/util/bpf_lock_contention.c         | 44 +++++++----
 .../perf/util/bpf_skel/lock_contention.bpf.c  | 15 ++--
 tools/perf/util/bpf_skel/lock_data.h          |  4 +-
 tools/perf/util/lock-contention.h             |  2 +
 5 files changed, 89 insertions(+), 51 deletions(-)

diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index 0593c6e636c6..0d11f301fd72 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -509,6 +509,34 @@ struct lock_stat *lock_stat_findnew(u64 addr, const char *name, int flags)
 	return NULL;
 }
 
+bool match_callstack_filter(struct machine *machine, u64 *callstack)
+{
+	struct map *kmap;
+	struct symbol *sym;
+	u64 ip;
+
+	if (list_empty(&callstack_filters))
+		return true;
+
+	for (int i = 0; i < max_stack_depth; i++) {
+		struct callstack_filter *filter;
+
+		if (!callstack || !callstack[i])
+			break;
+
+		ip = callstack[i];
+		sym = machine__find_kernel_symbol(machine, ip, &kmap);
+		if (sym == NULL)
+			continue;
+
+		list_for_each_entry(filter, &callstack_filters, list) {
+			if (strstr(sym->name, filter->name))
+				return true;
+		}
+	}
+	return false;
+}
+
 struct trace_lock_handler {
 	/* it's used on CONFIG_LOCKDEP */
 	int (*acquire_event)(struct evsel *evsel,
@@ -1070,12 +1098,6 @@ static int report_lock_contention_begin_event(struct evsel *evsel,
 		ls = lock_stat_findnew(key, name, flags);
 		if (!ls)
 			return -ENOMEM;
-
-		if (aggr_mode == LOCK_AGGR_CALLER && needs_callstack()) {
-			ls->callstack = get_callstack(sample, max_stack_depth);
-			if (ls->callstack == NULL)
-				return -ENOMEM;
-		}
 	}
 
 	if (filters.nr_types) {
@@ -1106,6 +1128,22 @@ static int report_lock_contention_begin_event(struct evsel *evsel,
 			return 0;
 	}
 
+	if (needs_callstack()) {
+		u64 *callstack = get_callstack(sample, max_stack_depth);
+		if (callstack == NULL)
+			return -ENOMEM;
+
+		if (!match_callstack_filter(machine, callstack)) {
+			free(callstack);
+			return 0;
+		}
+
+		if (ls->callstack == NULL)
+			ls->callstack = callstack;
+		else
+			free(callstack);
+	}
+
 	ts = thread_stat_findnew(sample->tid);
 	if (!ts)
 		return -ENOMEM;
@@ -1606,31 +1644,6 @@ static void print_contention_result(struct lock_contention *con)
 		if (!st->wait_time_total)
 			continue;
 
-		if (aggr_mode == LOCK_AGGR_CALLER && !list_empty(&callstack_filters)) {
-			struct map *kmap;
-			struct symbol *sym;
-			u64 ip;
-
-			for (int i = 0; i < max_stack_depth; i++) {
-				struct callstack_filter *filter;
-
-				if (!st->callstack || !st->callstack[i])
-					break;
-
-				ip = st->callstack[i];
-				sym = machine__find_kernel_symbol(con->machine, ip, &kmap);
-				if (sym == NULL)
-					continue;
-
-				list_for_each_entry(filter, &callstack_filters, list) {
-					if (strstr(sym->name, filter->name))
-						goto found;
-				}
-			}
-			continue;
-		}
-
-found:
 		list_for_each_entry(key, &lock_keys, list) {
 			key->print(key, st);
 			pr_info(" ");
diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index ead2898ba377..72cf81114982 100644
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -34,13 +34,15 @@ int lock_contention_prepare(struct lock_contention *con)
 	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) {
+	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 {
+	else
 		bpf_map__set_max_entries(skel->maps.task_data, 1);
+
+	if (con->save_callstack)
 		bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);
-	}
+	else
+		bpf_map__set_max_entries(skel->maps.stacks, 1);
 
 	if (target__has_cpu(target))
 		ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
@@ -146,6 +148,7 @@ int lock_contention_prepare(struct lock_contention *con)
 	/* these don't work well if in the rodata section */
 	skel->bss->stack_skip = con->stack_skip;
 	skel->bss->aggr_mode = con->aggr_mode;
+	skel->bss->needs_callstack = con->save_callstack;
 
 	lock_contention_bpf__attach(skel);
 	return 0;
@@ -177,7 +180,7 @@ static const char *lock_contention_get_name(struct lock_contention *con,
 
 	if (con->aggr_mode == LOCK_AGGR_TASK) {
 		struct contention_task_data task;
-		int pid = key->aggr_key;
+		int pid = key->pid;
 		int task_fd = bpf_map__fd(skel->maps.task_data);
 
 		/* do not update idle comm which contains CPU number */
@@ -194,7 +197,7 @@ static const char *lock_contention_get_name(struct lock_contention *con,
 	}
 
 	if (con->aggr_mode == LOCK_AGGR_ADDR) {
-		sym = machine__find_kernel_symbol(machine, key->aggr_key, &kmap);
+		sym = machine__find_kernel_symbol(machine, key->lock_addr, &kmap);
 		if (sym)
 			name = sym->name;
 		return name;
@@ -255,20 +258,35 @@ int lock_contention_read(struct lock_contention *con)
 
 	prev_key = NULL;
 	while (!bpf_map_get_next_key(fd, prev_key, &key)) {
-		s32 stack_id;
+		s64 ls_key;
 		const char *name;
 
 		/* to handle errors in the loop body */
 		err = -1;
 
 		bpf_map_lookup_elem(fd, &key, &data);
-
 		if (con->save_callstack) {
-			stack_id = key.aggr_key;
-			bpf_map_lookup_elem(stack, &stack_id, stack_trace);
+			bpf_map_lookup_elem(stack, &key.stack_id, stack_trace);
+
+			if (!match_callstack_filter(machine, stack_trace))
+				goto next;
 		}
 
-		st = lock_stat_find(key.aggr_key);
+		switch (con->aggr_mode) {
+		case LOCK_AGGR_CALLER:
+			ls_key = key.stack_id;
+			break;
+		case LOCK_AGGR_TASK:
+			ls_key = key.pid;
+			break;
+		case LOCK_AGGR_ADDR:
+			ls_key = key.lock_addr;
+			break;
+		default:
+			goto next;
+		}
+
+		st = lock_stat_find(ls_key);
 		if (st != NULL) {
 			st->wait_time_total += data.total_time;
 			if (st->wait_time_max < data.max_time)
@@ -283,7 +301,7 @@ int lock_contention_read(struct lock_contention *con)
 		}
 
 		name = lock_contention_get_name(con, &key, stack_trace);
-		st = lock_stat_findnew(key.aggr_key, name, data.flags);
+		st = lock_stat_findnew(ls_key, name, data.flags);
 		if (st == NULL)
 			break;
 
@@ -295,8 +313,6 @@ int lock_contention_read(struct lock_contention *con)
 		if (data.count)
 			st->avg_wait_time = data.total_time / data.count;
 
-		st->flags = data.flags;
-
 		if (con->save_callstack) {
 			st->callstack = memdup(stack_trace, stack_size);
 			if (st->callstack == NULL)
diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index ad0ca5d50557..7ce276ed987e 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -82,6 +82,7 @@ int has_cpu;
 int has_task;
 int has_type;
 int has_addr;
+int needs_callstack;
 int stack_skip;
 
 /* determine the key of lock stat */
@@ -173,7 +174,7 @@ int contention_begin(u64 *ctx)
 	pelem->lock = (__u64)ctx[0];
 	pelem->flags = (__u32)ctx[1];
 
-	if (aggr_mode == LOCK_AGGR_CALLER) {
+	if (needs_callstack) {
 		pelem->stack_id = bpf_get_stackid(ctx, &stacks,
 						  BPF_F_FAST_STACK_CMP | stack_skip);
 		if (pelem->stack_id < 0)
@@ -188,7 +189,7 @@ int contention_end(u64 *ctx)
 {
 	__u32 pid;
 	struct tstamp_data *pelem;
-	struct contention_key key;
+	struct contention_key key = {};
 	struct contention_data *data;
 	__u64 duration;
 
@@ -204,14 +205,18 @@ int contention_end(u64 *ctx)
 
 	switch (aggr_mode) {
 	case LOCK_AGGR_CALLER:
-		key.aggr_key = pelem->stack_id;
+		key.stack_id = pelem->stack_id;
 		break;
 	case LOCK_AGGR_TASK:
-		key.aggr_key = pid;
+		key.pid = pid;
 		update_task_data(pid);
+		if (needs_callstack)
+			key.stack_id = pelem->stack_id;
 		break;
 	case LOCK_AGGR_ADDR:
-		key.aggr_key = pelem->lock;
+		key.lock_addr = pelem->lock;
+		if (needs_callstack)
+			key.stack_id = pelem->stack_id;
 		break;
 	default:
 		/* should not happen */
diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
index ce71cf1a7e1e..3d35fd4407ac 100644
--- a/tools/perf/util/bpf_skel/lock_data.h
+++ b/tools/perf/util/bpf_skel/lock_data.h
@@ -4,7 +4,9 @@
 #define UTIL_BPF_SKEL_LOCK_DATA_H
 
 struct contention_key {
-	u64 aggr_key;  /* can be stack_id, pid or lock addr */
+	u32 stack_id;
+	u32 pid;
+	u64 lock_addr;
 };
 
 #define TASK_COMM_LEN  16
diff --git a/tools/perf/util/lock-contention.h b/tools/perf/util/lock-contention.h
index 39d5bfc77f4e..e5fc036108ec 100644
--- a/tools/perf/util/lock-contention.h
+++ b/tools/perf/util/lock-contention.h
@@ -68,6 +68,8 @@ struct lock_stat {
 struct lock_stat *lock_stat_find(u64 addr);
 struct lock_stat *lock_stat_findnew(u64 addr, const char *name, int flags);
 
+bool match_callstack_filter(struct machine *machine, u64 *callstack);
+
 /*
  * struct lock_seq_stat:
  * Place to put on state of one lock sequence
-- 
2.39.1.519.gcb327c4b5f-goog

Re: [PATCH v2 0/3] perf lock contention: Improve aggr x filter combination

[Arnaldo Carvalho de Melo]

Em Thu, Feb 02, 2023 at 06:13:21PM -0800, Namhyung Kim escreveu:
> Hello,
> 
> The callstack filter can be useful to debug lock issues but it has a
> limitation that it only works with caller aggregation mode (which is the
> default setting).  IOW it cannot filter by callstack when showing tasks
> or lock addresses/names.

Thanks, applied.

- Arnaldo

 
> But sometimes users want to use the filter for other aggregation mode.
> Like "show me lock addresses/names from this caller only" or "show me
> tasks having these callers".
> 
> When it's using tracepoint events from the data file, the situation is
> good since the tracepoints have all the necessary info.  But when using
> BPF it needs to extend the key of lock stat BPF map to have more than
> one info like 'pid + stack_id' or 'lock_addr + stack_id'.  As callstack
> filter works in userspace, it should save the both info.
> 
> With this change we can now use the -S/--callstack-filter with the
> -t/--threads option or -l/--lock-addr option.  It's also possible to use
> it with other filter options.
> 
> The following example shows the top 5 tasks that have contention
> somewhere in the epoll handling.
> 
>   $ sudo perf lock con -abt -S epoll -E5 -- sleep 1
>    contended   total wait     max wait     avg wait          pid   comm
> 
>            2     58.64 us     32.38 us     29.32 us      1514752   Chrome_IOThread
>            3     29.31 us     12.65 us      9.77 us         3773   Xorg
>            1     17.45 us     17.45 us     17.45 us      1514906   Chrome_ChildIOT
>            1     15.41 us     15.41 us     15.41 us      1515382   Chrome_ChildIOT
>            1     12.52 us     12.52 us     12.52 us       293878   IPC I/O Parent
> 
> You get get the code at 'perf/lock-filter-v1' branch in
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
> 
> Thanks,
> Namhyung
> 
> Namhyung Kim (3):
>   perf lock contention: Factor out lock_contention_get_name()
>   perf lock contention: Use lock_stat_find{,new}
>   perf lock contention: Support filters for different aggregation
> 
>  tools/perf/builtin-lock.c                     |  79 ++++----
>  tools/perf/util/Build                         |   5 +-
>  tools/perf/util/bpf_lock_contention.c         | 180 +++++++++++-------
>  .../perf/util/bpf_skel/lock_contention.bpf.c  |  15 +-
>  tools/perf/util/bpf_skel/lock_data.h          |   4 +-
>  tools/perf/util/lock-contention.h             |   5 +
>  6 files changed, 178 insertions(+), 110 deletions(-)
> 
> -- 
> 2.39.1.519.gcb327c4b5f-goog
> 

-- 

- Arnaldo