perf machine: Use hashtable for machine threads

To process any events, it needs to find the thread in the machine first.
The machine maintains a rb tree to store all threads. The rb tree is
protected by a rw lock.

It is not a problem for current perf which serially processing events.
However, it will have scalability performance issue to process events in
parallel, especially on a heavy load system which have many threads.

Introduce a hashtable to divide the big rb tree into many samll rb tree
for threads. The index is thread id % hashtable size. It can reduce the
lock contention.

Committer notes:

Renamed some variables and function names to reduce semantic confusion:

  'struct threads' pointers: thread -> threads
  threads hastable index: tid -> hash_bucket
  struct threads *machine__thread() -> machine__threads()
  Cast tid to (unsigned int) to handle -1 in machine__threads() (Kan Liang)

Signed-off-by: Kan Liang <kan.liang@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Lukasz Odzioba <lukasz.odzioba@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1505096603-215017-2-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 11 insertions, 8 deletions

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 771ddab94bb0..ee8c6e814437 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -2730,20 +2730,23 @@ DEFINE_RESORT_RB(threads, (thread__nr_events(a->thread->priv) < thread__nr_event
 
 static size_t trace__fprintf_thread_summary(struct trace *trace, FILE *fp)
 {
-	DECLARE_RESORT_RB_MACHINE_THREADS(threads, trace->host);
 	size_t printed = trace__fprintf_threads_header(fp);
 	struct rb_node *nd;
+	int i;
 
-	if (threads == NULL) {
-		fprintf(fp, "%s", "Error sorting output by nr_events!\n");
-		return 0;
-	}
+	for (i = 0; i < THREADS__TABLE_SIZE; i++) {
+		DECLARE_RESORT_RB_MACHINE_THREADS(threads, trace->host, i);
 
-	resort_rb__for_each_entry(nd, threads)
-		printed += trace__fprintf_thread(fp, threads_entry->thread, trace);
+		if (threads == NULL) {
+			fprintf(fp, "%s", "Error sorting output by nr_events!\n");
+			return 0;
+		}
 
-	resort_rb__delete(threads);
+		resort_rb__for_each_entry(nd, threads)
+			printed += trace__fprintf_thread(fp, threads_entry->thread, trace);
 
+		resort_rb__delete(threads);
+	}
 	return printed;
 }