[PATCH 13/40] perf tools: Convert dead thread list into rbtree

From: Namhyung Kim
Date: Sun May 17 2015 - 20:49:16 EST

Currently perf maintains dead threads in a linked list but this can be
a problem if someone needs to search from it especially in a large
session which might have many dead threads. Convert it to a rbtree
like normal threads and it'll be used later with multi-file changes.

The list node is now used for chaining dead threads of same tid since
it's easier to handle such threads in time order.

Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
tools/perf/util/machine.c | 80 ++++++++++++++++++++++++++++++++++++++++++-----
tools/perf/util/machine.h | 2 +-
tools/perf/util/thread.c | 21 +++++++++++--
tools/perf/util/thread.h | 11 +++----
4 files changed, 96 insertions(+), 18 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 34bf89f7f4f3..ae07b84a40f5 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -30,8 +30,8 @@ int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
dsos__init(&machine->kernel_dsos);

machine->threads = RB_ROOT;
+ machine->dead_threads = RB_ROOT;
pthread_rwlock_init(&machine->threads_lock, NULL);
- INIT_LIST_HEAD(&machine->dead_threads);
machine->last_match = NULL;

machine->vdso_info = NULL;
@@ -93,6 +93,29 @@ static void dsos__delete(struct dsos *dsos)
}
}

+static void machine__delete_dead_threads(struct machine *machine)
+{
+ struct rb_node *nd = rb_first(&machine->dead_threads);
+
+ while (nd) {
+ struct thread *t = rb_entry(nd, struct thread, rb_node);
+ struct thread *pos;
+
+ nd = rb_next(nd);
+ rb_erase(&t->rb_node, &machine->dead_threads);
+ RB_CLEAR_NODE(&t->rb_node);
+
+ while (!list_empty(&t->tid_node)) {
+ pos = list_first_entry(&t->tid_node,
+ struct thread, tid_node);
+ list_del_init(&pos->tid_node);
+ thread__delete(pos);
+ }
+
+ thread__delete(t);
+ }
+}
+
void machine__delete_threads(struct machine *machine)
{
struct rb_node *nd;
@@ -106,6 +129,8 @@ void machine__delete_threads(struct machine *machine)
__machine__remove_thread(machine, t, false);
}
pthread_rwlock_unlock(&machine->threads_lock);
+
+ machine__delete_dead_threads(machine);
}

void machine__exit(struct machine *machine)
@@ -1308,6 +1333,10 @@ int machine__process_mmap_event(struct machine *machine, union perf_event *event

static void __machine__remove_thread(struct machine *machine, struct thread *th, bool lock)
{
+ struct rb_node **p = &machine->dead_threads.rb_node;
+ struct rb_node *parent = NULL;
+ struct thread *pos;
+
if (machine->last_match == th)
machine->last_match = NULL;

@@ -1316,15 +1345,43 @@ static void __machine__remove_thread(struct machine *machine, struct thread *th,
pthread_rwlock_wrlock(&machine->threads_lock);
rb_erase(&th->rb_node, &machine->threads);
RB_CLEAR_NODE(&th->rb_node);
+
+ th->dead = true;
+
+ /*
+ * No need to have an additional reference for non-index file.
+ */
+ if (!perf_has_index) {
+ thread__put(th);
+ goto out;
+ }
+
/*
- * Move it first to the dead_threads list, then drop the reference,
- * if this is the last reference, then the thread__delete destructor
- * will be called and we will remove it from the dead_threads list.
+ * For indexed file, We may have references to this (dead)
+ * thread, as samples are processed after fork/exit events.
+ * Just move them to a separate rbtree.
*/
- list_add_tail(&th->node, &machine->dead_threads);
+ while (*p != NULL) {
+ parent = *p;
+ pos = rb_entry(parent, struct thread, rb_node);
+
+ if (pos->tid == th->tid) {
+ list_add_tail(&th->tid_node, &pos->tid_node);
+ goto out;
+ }
+
+ if (th->tid < pos->tid)
+ p = &(*p)->rb_left;
+ else
+ p = &(*p)->rb_right;
+ }
+
+ rb_link_node(&th->rb_node, parent, p);
+ rb_insert_color(&th->rb_node, &machine->dead_threads);
+
+out:
if (lock)
pthread_rwlock_unlock(&machine->threads_lock);
- thread__put(th);
}

void machine__remove_thread(struct machine *machine, struct thread *th)
@@ -1826,7 +1883,7 @@ int machine__for_each_thread(struct machine *machine,
void *priv)
{
struct rb_node *nd;
- struct thread *thread;
+ struct thread *thread, *pos;
int rc = 0;

for (nd = rb_first(&machine->threads); nd; nd = rb_next(nd)) {
@@ -1836,10 +1893,17 @@ int machine__for_each_thread(struct machine *machine,
return rc;
}

- list_for_each_entry(thread, &machine->dead_threads, node) {
+ for (nd = rb_first(&machine->dead_threads); nd; nd = rb_next(nd)) {
+ thread = rb_entry(nd, struct thread, rb_node);
rc = fn(thread, priv);
if (rc != 0)
return rc;
+
+ list_for_each_entry(pos, &thread->tid_node, tid_node) {
+ rc = fn(pos, priv);
+ if (rc != 0)
+ return rc;
+ }
}
return rc;
}
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index c7963c63c474..53cdd1aad3ff 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -30,8 +30,8 @@ struct machine {
bool comm_exec;
char *root_dir;
struct rb_root threads;
+ struct rb_root dead_threads;
pthread_rwlock_t threads_lock;
- struct list_head dead_threads;
struct thread *last_match;
struct vdso_info *vdso_info;
struct dsos user_dsos;
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 962558024415..ccf1808348fe 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -9,6 +9,7 @@
#include "debug.h"
#include "comm.h"
#include "unwind.h"
+#include "machine.h"

int thread__init_map_groups(struct thread *thread, struct machine *machine)
{
@@ -38,6 +39,7 @@ struct thread *thread__new(pid_t pid, pid_t tid)
thread->ppid = -1;
thread->cpu = -1;
INIT_LIST_HEAD(&thread->comm_list);
+ INIT_LIST_HEAD(&thread->tid_node);

if (unwind__prepare_access(thread) < 0)
goto err_thread;
@@ -54,7 +56,7 @@ struct thread *thread__new(pid_t pid, pid_t tid)

list_add(&comm->list, &thread->comm_list);
atomic_set(&thread->refcnt, 0);
- INIT_LIST_HEAD(&thread->node);
+ INIT_LIST_HEAD(&thread->tid_node);
RB_CLEAR_NODE(&thread->rb_node);
}

@@ -70,7 +72,7 @@ void thread__delete(struct thread *thread)
struct comm *comm, *tmp;

BUG_ON(!RB_EMPTY_NODE(&thread->rb_node));
- BUG_ON(!list_empty(&thread->node));
+ BUG_ON(!list_empty(&thread->tid_node));

thread_stack__free(thread);

@@ -97,7 +99,20 @@ struct thread *thread__get(struct thread *thread)
void thread__put(struct thread *thread)
{
if (thread && atomic_dec_and_test(&thread->refcnt)) {
- list_del_init(&thread->node);
+ if (!RB_EMPTY_NODE(&thread->rb_node)) {
+ struct machine *machine = thread->mg->machine;
+
+ if (thread->dead) {
+ rb_erase(&thread->rb_node,
+ &machine->dead_threads);
+ } else {
+ rb_erase(&thread->rb_node,
+ &machine->threads);
+ }
+ RB_CLEAR_NODE(&thread->rb_node);
+ }
+
+ list_del_init(&thread->tid_node);
thread__delete(thread);
}
}
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index 903cfaf2628d..d6f6f150f3ff 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -13,10 +13,8 @@
struct thread_stack;

struct thread {
- union {
- struct rb_node rb_node;
- struct list_head node;
- };
+ struct rb_node rb_node;
+ struct list_head tid_node;
struct map_groups *mg;
pid_t pid_; /* Not all tools update this */
pid_t tid;
@@ -25,7 +23,8 @@ struct thread {
atomic_t refcnt;
char shortname[3];
bool comm_set;
- bool dead; /* if set thread has exited */
+ bool exited; /* if set thread has exited */
+ bool dead; /* thread is in dead_threads list */
struct list_head comm_list;
int comm_len;
u64 db_id;
@@ -54,7 +53,7 @@ static inline void __thread__zput(struct thread **thread)

static inline void thread__exited(struct thread *thread)
{
- thread->dead = true;
+ thread->exited = true;
}

int __thread__set_comm(struct thread *thread, const char *comm, u64 timestamp,
--
2.4.0

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