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SubjectRe: [PATCH 14/37] perf tools: Convert dead thread list into rbtree
On Fri, Dec 26, 2014 at 8:05 AM, Jiri Olsa <jolsa@redhat.com> wrote:
> On Wed, Dec 24, 2014 at 04:15:10PM +0900, Namhyung Kim wrote:
>
> SNIP
>
>>
>> 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;
>> + }
>
> hum, why is this 'new list' in thread object necessary? why not
> to store all in the tree?

No absolute reason, but I just wanted to keep them in a single place
and to see how many of them exist easily. We could compare pid and
then timestamp so that it can be in a single rbtree.

>
>
>> +
>> + if (th->tid < pos->tid)
>> + p = &(*p)->rb_left;
>> + else
>> + p = &(*p)->rb_right;
>> + }
>> +
>
> SNIP
>
>> 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;
>> @@ -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 */
>
> looks like this also changes the logic (new exited flag),
> not just the dead threads storage wheel

AFAICS the 'dead' flag is not used other than thread__exited(). And
it confused me a dead thread might not be in a dead_threads tree (or
list). So I changed the name and no logical change intended.

Thanks,
Namhyung


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