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 <fweis...@gmail.com>
Signed-off-by: Namhyung Kim <namhy...@kernel.org>
---
 tools/perf/util/machine.c | 70 +++++++++++++++++++++++++++++++++++++++++------
 tools/perf/util/machine.h |  2 +-
 tools/perf/util/thread.c  |  1 +
 tools/perf/util/thread.h  | 11 ++++----
 4 files changed, 68 insertions(+), 16 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 9e0f60a7e7b3..6b8236dc4367 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -28,7 +28,7 @@ int machine__init(struct machine *machine, const char 
*root_dir, pid_t pid)
        dsos__init(&machine->kernel_dsos);
 
        machine->threads = RB_ROOT;
-       INIT_LIST_HEAD(&machine->dead_threads);
+       machine->dead_threads = RB_ROOT;
        machine->last_match = NULL;
 
        machine->vdso_info = NULL;
@@ -91,10 +91,22 @@ static void dsos__delete(struct dsos *dsos)
 
 void machine__delete_dead_threads(struct machine *machine)
 {
-       struct thread *n, *t;
+       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);
+
+               while (!list_empty(&t->tid_node)) {
+                       pos = list_first_entry(&t->tid_node,
+                                              struct thread, tid_node);
+                       list_del(&pos->tid_node);
+                       thread__delete(pos);
+               }
 
-       list_for_each_entry_safe(t, n, &machine->dead_threads, node) {
-               list_del(&t->node);
                thread__delete(t);
        }
 }
@@ -106,8 +118,8 @@ void machine__delete_threads(struct machine *machine)
        while (nd) {
                struct thread *t = rb_entry(nd, struct thread, rb_node);
 
-               rb_erase(&t->rb_node, &machine->threads);
                nd = rb_next(nd);
+               rb_erase(&t->rb_node, &machine->threads);
                thread__delete(t);
        }
 }
@@ -1238,13 +1250,46 @@ int machine__process_mmap_event(struct machine 
*machine, union perf_event *event
 
 static void machine__remove_thread(struct machine *machine, struct thread *th)
 {
+       struct rb_node **p = &machine->dead_threads.rb_node;
+       struct rb_node *parent = NULL;
+       struct thread *pos;
+
        machine->last_match = NULL;
        rb_erase(&th->rb_node, &machine->threads);
+
+       th->dead = true;
+
        /*
         * We may have references to this thread, for instance in some 
hist_entry
-        * instances, so just move them to a separate list.
+        * instances, so just move them to a separate list in 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) {
+                       struct thread *old;
+
+                       /* sort by time */
+                       list_for_each_entry(old, &pos->tid_node, tid_node) {
+                               if (th->start_time >= old->start_time) {
+                                       pos = old;
+                                       break;
+                               }
+                       }
+
+                       list_add_tail(&th->tid_node, &pos->tid_node);
+                       return;
+               }
+
+               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);
 }
 
 int machine__process_fork_event(struct machine *machine, union perf_event 
*event,
@@ -1729,7 +1774,7 @@ 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)) {
@@ -1739,10 +1784,17 @@ 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 e8b7779a0a3f..4349946a38ff 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -30,7 +30,7 @@ struct machine {
        bool              comm_exec;
        char              *root_dir;
        struct rb_root    threads;
-       struct list_head  dead_threads;
+       struct rb_root    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 ad96725105c2..c9ae0e1599da 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -38,6 +38,7 @@ 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;
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index be67c3bad5e7..21268e66b2ad 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -11,10 +11,8 @@
 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;
@@ -22,7 +20,8 @@ struct thread {
        int                     cpu;
        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;
@@ -39,7 +38,7 @@ int thread__init_map_groups(struct thread *thread, struct 
machine *machine);
 void thread__delete(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,
-- 
2.2.2

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