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SubjectRe: [PATCH 14/37] perf tools: Convert dead thread list into rbtree
On 12/24/14 12:15 AM, Namhyung Kim wrote:
> @@ -106,8 +117,8 @@ 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);
> }
> }

unrelated to dead threads. Bug fix? separate patch?


> @@ -1236,13 +1247,36 @@ 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) {
> + list_add_tail(&th->node, &pos->node);
> + return;
> + }

So you have a linked list for tid collisions (not mentioned in the git log).

> +
> + 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,
> @@ -1649,7 +1683,7 @@ int machine__for_each_thread(struct machine *machine,

---8<---

> diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
> index 0b6dcd70bc8b..413f28cf689b 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 node;
> struct map_groups *mg;
> pid_t pid_; /* Not all tools update this */
> pid_t tid;

could use better names for rb_node and node. rb_node is the entry in the
dead_threads tree - dead_node?; node is the linked list for tid
collisions - tid_node?

David


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