Messages in this thread | | | Date | Tue, 20 Jun 2017 14:36:25 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi |
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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; };
... 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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