Messages in this thread | | | Subject | Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi | From | Alexey Budankov <> | Date | Tue, 20 Jun 2017 20:10:06 +0300 |
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On 20.06.2017 19:37, Mark Rutland wrote: > On Tue, Jun 20, 2017 at 06:22:56PM +0300, Alexey Budankov wrote: >> 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? > > Yes; *every* group leader would be directly in the threaded rb tree.
In this case the tree's key heeds to be something trickier than just event->cpu. To avoid that complication group_list is introduced. BTW, addressing perf_event_tree_delete issue doesn't look like a big change now:
static void perf_cpu_tree_delete(struct rb_root *tree, struct perf_event *event) { struct perf_event *next;
WARN_ON_ONCE(!tree || !event);
list_del_init(&event->group_entry);
if (!RB_EMPTY_NODE(&event->group_node)) { if (!list_empty(&event->group_list)) { next = list_first_entry(&event->group_list, struct perf_event, group_entry); list_replace_init(&event->group_list, &next->group_list); rb_replace_node(&event->group_node, &next->group_node, tree); } else { rb_erase(&event->group_node, tree); } RB_CLEAR_NODE(&event->group_node); } }
> >> Which objects does the head keep? > > Sorry, I'm not sure how to answer that. Did the above clarify? > > If not, could you rephrase the question? > > Thanks, > Mark. >
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