[PATCH v2 2/6] perf trace: Ignore thread hashing in summary

Ian Rogers
2024-02-27T22:02:06Z

Commit 91e467bc568f ("perf machine: Use hashtable for machine
threads") made the iteration of thread tids unordered. The perf trace
--summary output sorts and prints each hash bucket, rather than all
threads globally. Change this behavior by turn all threads into a
list, sort the list by number of trace events then by tids, finally
print the list. This also allows the rbtree in threads to be not
accessed outside of machine.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/builtin-trace.c | 41 +++++++++++++++++++++----------------
tools/perf/util/rb_resort.h | 5 -----
2 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 109b8e64fe69..90eaff8c0f6e 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -74,6 +74,7 @@
#include <linux/err.h>
#include <linux/filter.h>
#include <linux/kernel.h>
+#include <linux/list_sort.h>
#include <linux/random.h>
#include <linux/stringify.h>
#include <linux/time64.h>
@@ -4312,34 +4313,38 @@ static unsigned long thread__nr_events(struct thread_trace *ttrace)
return ttrace ? ttrace->nr_events : 0;
}

-DEFINE_RESORT_RB(threads,
- (thread__nr_events(thread__priv(a->thread)) <
- thread__nr_events(thread__priv(b->thread))),
- struct thread *thread;
-)
+static int trace_nr_events_cmp(void *priv __maybe_unused,
+ const struct list_head *la,
+ const struct list_head *lb)
{
- entry->thread = rb_entry(nd, struct thread_rb_node, rb_node)->thread;
+ struct thread_list *a = list_entry(la, struct thread_list, list);
+ struct thread_list *b = list_entry(lb, struct thread_list, list);
+ unsigned long a_nr_events = thread__nr_events(thread__priv(a->thread));
+ unsigned long b_nr_events = thread__nr_events(thread__priv(b->thread));
+
+ if (a_nr_events != b_nr_events)
+ return a_nr_events < b_nr_events ? -1 : 1;
+
+ /* Identical number of threads, place smaller tids first. */
+ return thread__tid(a->thread) < thread__tid(b->thread)
+ ? -1
+ : (thread__tid(a->thread) > thread__tid(b->thread) ? 1 : 0);
}

static size_t trace__fprintf_thread_summary(struct trace *trace, FILE *fp)
{
size_t printed = trace__fprintf_threads_header(fp);
- struct rb_node *nd;
- int i;
-
- for (i = 0; i < THREADS__TABLE_SIZE; i++) {
- DECLARE_RESORT_RB_MACHINE_THREADS(threads, trace->host, i);
+ LIST_HEAD(threads);

- if (threads == NULL) {
- fprintf(fp, "%s", "Error sorting output by nr_events!\n");
- return 0;
- }
+ if (machine__thread_list(trace->host, &threads) == 0) {
+ struct thread_list *pos;

- resort_rb__for_each_entry(nd, threads)
- printed += trace__fprintf_thread(fp, threads_entry->thread, trace);
+ list_sort(NULL, &threads, trace_nr_events_cmp);

- resort_rb__delete(threads);
+ list_for_each_entry(pos, &threads, list)
+ printed += trace__fprintf_thread(fp, pos->thread, trace);
}
+ thread_list__delete(&threads);
return printed;
}

diff --git a/tools/perf/util/rb_resort.h b/tools/perf/util/rb_resort.h
index 376e86cb4c3c..d927a0d25052 100644
--- a/tools/perf/util/rb_resort.h
+++ b/tools/perf/util/rb_resort.h
@@ -143,9 +143,4 @@ struct __name##_sorted *__name = __name##_sorted__new
DECLARE_RESORT_RB(__name)(&__ilist->rblist.entries.rb_root, \
__ilist->rblist.nr_entries)

-/* For 'struct machine->threads' */
-#define DECLARE_RESORT_RB_MACHINE_THREADS(__name, __machine, hash_bucket) \
- DECLARE_RESORT_RB(__name)(&__machine->threads[hash_bucket].entries.rb_root, \
- __machine->threads[hash_bucket].nr)
-
#endif /* _PERF_RESORT_RB_H_ */
--
2.44.0.rc1.240.g4c46232300-goog