[PATCH 18/49] perf tools: Introduce machine__find*_thread_by_time()

[Jiri Olsa]

From: Namhyung Kim <namhyung@xxxxxxxxxx>

With data file indexing is enabled, it needs to search thread based on
sample time since sample processing is done after other (task, comm and
mmap) events are processed.  This can be a problem if a session is very
long and pid is recycled - in that case it'll only see the last one.

So keep thread start time in it, and search thread based on the time.
This patch introduces machine__find{,new}_thread_by_time() function
for this.  It'll first search current (i.e. recent) thread rbtree and
then dead thread tree (and tid list).  If it couldn't find anyone,
it'll create a new (missing) thread.

The sample timestamp of 0 means that this is called from synthesized
event so just use current rbtree.  The timestamp will be -1 if sample
didn't record the timestamp so will see current threads automatically.

Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-fxl42zknqoke9d9jix6fvu8w@xxxxxxxxxxxxxx
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
 tools/perf/tests/dwarf-unwind.c |   4 +-
 tools/perf/tests/hists_common.c |   2 +-
 tools/perf/tests/hists_link.c   |   2 +-
 tools/perf/util/event.c         |   6 +-
 tools/perf/util/machine.c       | 128 +++++++++++++++++++++++++++++++++++++++-
 tools/perf/util/machine.h       |  10 +++-
 tools/perf/util/thread.c        |   5 ++
 tools/perf/util/thread.h        |   1 +
 8 files changed, 148 insertions(+), 10 deletions(-)

diff --git a/tools/perf/tests/dwarf-unwind.c b/tools/perf/tests/dwarf-unwind.c
index ac40e05bcab4..490f983f894e 100644
--- a/tools/perf/tests/dwarf-unwind.c
+++ b/tools/perf/tests/dwarf-unwind.c
@@ -79,12 +79,10 @@ static int unwind_entry(struct unwind_entry *entry, void *arg)
 
 static noinline int unwind_thread(struct thread *thread)
 {
-	struct perf_sample sample;
+	struct perf_sample sample = { .time = -1ULL, };
 	unsigned long cnt = 0;
 	int err = -1;
 
-	memset(&sample, 0, sizeof(sample));
-
 	if (test__arch_unwind_sample(&sample, thread)) {
 		pr_debug("failed to get unwind sample\n");
 		goto out;
diff --git a/tools/perf/tests/hists_common.c b/tools/perf/tests/hists_common.c
index f7c5b613d667..c70d7b855df9 100644
--- a/tools/perf/tests/hists_common.c
+++ b/tools/perf/tests/hists_common.c
@@ -104,7 +104,7 @@ struct machine *setup_fake_machine(struct machines *machines)
 
 	for (i = 0; i < ARRAY_SIZE(fake_mmap_info); i++) {
 		struct perf_sample sample = {
-			.cpumode = PERF_RECORD_MISC_USER,
+			.cpumode = PERF_RECORD_MISC_USER, .time = -1ULL,
 		};
 		union perf_event fake_mmap_event = {
 			.mmap = {
diff --git a/tools/perf/tests/hists_link.c b/tools/perf/tests/hists_link.c
index 9a9d06cb0222..3e07928da53c 100644
--- a/tools/perf/tests/hists_link.c
+++ b/tools/perf/tests/hists_link.c
@@ -67,7 +67,7 @@ static int add_hist_entries(struct perf_evlist *evlist, struct machine *machine)
 	struct perf_evsel *evsel;
 	struct addr_location al;
 	struct hist_entry *he;
-	struct perf_sample sample = { .period = 1, .weight = 1, };
+	struct perf_sample sample = { .period = 1, .weight = 1, .time = -1ULL, };
 	size_t i = 0, k;
 
 	/*
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 7c7a8090fb07..14c4cf5cd707 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -21,6 +21,7 @@
 #include "thread.h"
 #include "thread_map.h"
 #include "sane_ctype.h"
+#include "session.h"
 #include "symbol/kallsyms.h"
 #include "asm/bug.h"
 #include "stat.h"
@@ -1584,9 +1585,10 @@ void thread__find_addr_location(struct thread *thread,
 int machine__resolve(struct machine *machine, struct addr_location *al,
 		     struct perf_sample *sample)
 {
-	struct thread *thread = machine__findnew_thread(machine, sample->pid,
-							sample->tid);
+	struct thread *thread;
 
+	thread = machine__findnew_thread_by_time(machine, sample->pid,
+						 sample->tid, sample->time);
 	if (thread == NULL)
 		return -1;
 
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index a4d0dd57ad18..1be0fa64e3ca 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -531,6 +531,122 @@ struct thread *machine__find_thread(struct machine *machine, pid_t pid,
 	return th;
 }
 
+static struct thread *
+__machine__findnew_thread_by_time(struct machine *machine, struct threads *threads,
+				  pid_t pid, pid_t tid, u64 timestamp, bool create)
+{
+	struct thread *curr, *pos, *new;
+	struct thread *th = NULL;
+	struct rb_node **p;
+	struct rb_node *parent = NULL;
+
+	if (!perf_has_index)
+		return ____machine__findnew_thread(machine, threads, pid, tid, create);
+
+	/* lookup current thread first */
+	curr = ____machine__findnew_thread(machine, threads, pid, tid, false);
+	if (curr && timestamp >= curr->start_time)
+		return curr;
+
+	/* and then check dead threads tree & list */
+	p = &threads->dead.rb_node;
+	while (*p != NULL) {
+		parent = *p;
+		th = rb_entry(parent, struct thread, rb_node);
+
+		if (th->tid == tid) {
+			list_for_each_entry(pos, &th->tid_list, tid_list) {
+				if (timestamp >= pos->start_time &&
+				    pos->start_time > th->start_time) {
+					th = pos;
+					break;
+				}
+			}
+
+			if (timestamp >= th->start_time) {
+				machine__update_thread_pid(machine, th, pid);
+				return th;
+			}
+			break;
+		}
+
+		if (tid < th->tid)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+
+	if (!create)
+		return NULL;
+
+	if (!curr && !*p) {
+		/* found no thread.  create one as current thread */
+		return __machine__findnew_thread(machine, pid, tid);
+	}
+
+	new = thread__new(pid, tid);
+	if (new == NULL)
+		return NULL;
+
+	new->dead = true;
+	new->start_time = timestamp;
+
+	if (*p) {
+		list_for_each_entry(pos, &th->tid_list, tid_list) {
+			/* sort by time */
+			if (timestamp >= pos->start_time) {
+				th = pos;
+				break;
+			}
+		}
+		list_add_tail(&new->tid_list, &th->tid_list);
+	} else {
+		rb_link_node(&new->rb_node, parent, p);
+		rb_insert_color(&new->rb_node, &threads->dead);
+	}
+
+	thread__get(new);
+
+	/*
+	 * We have to initialize map_groups separately
+	 * after rb tree is updated.
+	 *
+	 * The reason is that we call machine__findnew_thread
+	 * within thread__init_map_groups to find the thread
+	 * leader and that would screwed the rb tree.
+	 */
+	if (thread__init_map_groups(new, machine))
+		thread__zput(new);
+
+	return new;
+}
+
+struct thread *machine__find_thread_by_time(struct machine *machine, pid_t pid,
+					    pid_t tid, u64 timestamp)
+{
+	struct threads *threads = machine__threads(machine, tid);
+	struct thread *th;
+
+	down_write(&threads->lock);
+	th = thread__get(__machine__findnew_thread_by_time(machine, threads, pid, tid,
+							   timestamp, false));
+	up_write(&threads->lock);
+	return th;
+}
+
+struct thread *machine__findnew_thread_by_time(struct machine *machine, pid_t pid,
+					       pid_t tid, u64 timestamp)
+{
+	struct threads *threads = machine__threads(machine, tid);
+	struct thread *th;
+
+	down_write(&threads->lock);
+	th = thread__get(__machine__findnew_thread_by_time(machine, threads, pid, tid,
+							   timestamp, true));
+	up_write(&threads->lock);
+	return th;
+}
+
 struct comm *machine__thread_exec_comm(struct machine *machine,
 				       struct thread *thread)
 {
@@ -1443,7 +1559,7 @@ int machine__process_mmap2_event(struct machine *machine,
 	}
 
 	thread = machine__findnew_thread(machine, event->mmap2.pid,
-					event->mmap2.tid);
+					 event->mmap2.tid);
 	if (thread == NULL)
 		goto out_problem;
 
@@ -1574,6 +1690,16 @@ static void __machine__remove_thread(struct machine *machine, struct thread *th,
 		pos = rb_entry(parent, struct thread, rb_node);
 
 		if (pos->tid == th->tid) {
+			struct thread *old;
+
+			/* sort by time */
+			list_for_each_entry(old, &pos->tid_list, tid_list) {
+				if (th->start_time >= old->start_time) {
+					pos = old;
+					break;
+				}
+			}
+
 			list_add_tail(&th->tid_list, &pos->tid_list);
 			goto out;
 		}
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index 1d1a2f199f90..8eca8af88d02 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -91,8 +91,6 @@ static inline bool machine__kernel_ip(struct machine *machine, u64 ip)
 	return ip >= kernel_start;
 }
 
-struct thread *machine__find_thread(struct machine *machine, pid_t pid,
-				    pid_t tid);
 struct comm *machine__thread_exec_comm(struct machine *machine,
 				       struct thread *thread);
 
@@ -185,6 +183,14 @@ static inline bool machine__is_host(struct machine *machine)
 
 struct thread *__machine__findnew_thread(struct machine *machine, pid_t pid, pid_t tid);
 struct thread *machine__findnew_thread(struct machine *machine, pid_t pid, pid_t tid);
+struct thread *machine__find_thread(struct machine *machine, pid_t pid,
+				    pid_t tid);
+struct thread *machine__findnew_thread_by_time(struct machine *machine,
+					       pid_t pid, pid_t tid,
+					       u64 timestamp);
+struct thread *machine__find_thread_by_time(struct machine *machine,
+					    pid_t pid, pid_t tid,
+					    u64 timestamp);
 
 struct dso *machine__findnew_dso(struct machine *machine, const char *filename);
 
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index b5ac28731c01..38510a40c898 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -225,6 +225,10 @@ static int ____thread__set_comm(struct thread *thread, const char *str,
 	/* Override the default :tid entry */
 	if (!thread->comm_set) {
 		int err = comm__override(curr, str, timestamp, exec);
+
+		if (!thread->start_time)
+			thread->start_time = timestamp;
+
 		if (err)
 			return err;
 	} else {
@@ -409,6 +413,7 @@ int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp)
 	}
 
 	thread->ppid = parent->tid;
+	thread->start_time = timestamp;
 	return thread__clone_map_groups(thread, parent);
 }
 
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index 0db517e9a1a0..90bf1d01fcf3 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -33,6 +33,7 @@ struct thread {
 	struct list_head	comm_list;
 	struct rw_semaphore	comm_lock;
 	u64			db_id;
+	u64			start_time;
 
 	void			*priv;
 	struct thread_stack	*ts;
-- 
2.13.6