On 20.06.2017 16:36, Mark Rutland wrote:
On Mon, Jun 19, 2017 at 11:31:59PM +0300, Alexey Budankov wrote:
On 15.06.2017 22:56, Mark Rutland wrote:
On Thu, Jun 15, 2017 at 08:41:42PM +0300, Alexey Budankov wrote:
+static int
+perf_cpu_tree_iterate(struct rb_root *tree,
+               perf_cpu_tree_callback_t callback, void *data)
+{
+       int ret = 0;
+       struct rb_node *node;
+       struct perf_event *event;
+
+       WARN_ON_ONCE(!tree);
+
+       for (node = rb_first(tree); node; node = rb_next(node)) {
+               struct perf_event *node_event = container_of(node,
+                               struct perf_event, group_node);
+
+               list_for_each_entry(event, &node_event->group_list,
+                               group_list_entry) {
+                       ret = callback(event, data);
+                       if (ret)
+                               return ret;
+               }
+       }
+
+       return 0;
  }

If you need to iterate over every event, you can use the list that
threads the whole tree.

Could you please explain more on that?

In Peter's original suggestion, we'd use a threaded tree rather than a
tree of lists.

i.e. you'd have something like:

struct threaded_rb_node {
        struct rb_node   node;
        struct list_head head;
};

Is this for every group leader? Which objects does the head keep?


... with the tree and list covering all nodes, in the same order:

Tree:

      3
     / \
    /   \
   1     5
  / \   / \
0   2 4   6

List:

0 - 1 - 2 - 3 - 4 - 5 - 6

... that way you can search using the tree, and iterate using the list,
even when you wan to iterate over sub-lists.

Thanks,
Mark.


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