Add tools/busy_threads for spawning N busy-wait threads for debugging
Change-Id: I7deec1f6499f32077bc6db1b4a3afa01785617fe
diff --git a/BUILD.gn b/BUILD.gn
index ee9ed13..3b5e5e7 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -73,6 +73,7 @@
]
if (is_linux || is_android) {
deps += [ "tools/skippy" ]
+ deps += [ "tools/busy_threads" ]
}
if (is_fuzzer) {
deps += [ ":fuzzers" ]
diff --git a/tools/busy_threads/BUILD.gn b/tools/busy_threads/BUILD.gn
new file mode 100644
index 0000000..0f33776
--- /dev/null
+++ b/tools/busy_threads/BUILD.gn
@@ -0,0 +1,24 @@
+# Copyright (C) 2019 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+executable("busy_threads") {
+ testonly = true
+ deps = [
+ "../../gn:default_deps",
+ "../../src/base",
+ ]
+ sources = [
+ "busy_threads.cc",
+ ]
+}
diff --git a/tools/busy_threads/busy_threads.cc b/tools/busy_threads/busy_threads.cc
new file mode 100644
index 0000000..03677cd
--- /dev/null
+++ b/tools/busy_threads/busy_threads.cc
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <getopt.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#include <thread>
+
+#include "perfetto/base/logging.h"
+#include "perfetto/base/time.h"
+
+// Spawns the requested number threads that busy-wait for a fixed duration, and
+// then yield.
+
+namespace perfetto {
+namespace {
+
+constexpr int64_t kBusyWaitPeriodNs = 1000 * 1000;
+
+__attribute__((noreturn)) void BusyWait() {
+ while (1) {
+ base::TimeNanos start = base::GetWallTimeNs();
+ while ((base::GetWallTimeNs() - start).count() < kBusyWaitPeriodNs) {
+ for (int i = 0; i < 10000; i++) {
+ asm volatile("" ::: "memory");
+ }
+ }
+ std::this_thread::yield();
+ }
+}
+
+int BusyThreadsMain(int argc, char** argv) {
+ int num_threads = -1;
+
+ static struct option long_options[] = {
+ {"threads", required_argument, nullptr, 't'}, {nullptr, 0, nullptr, 0}};
+ int option_index;
+ int c;
+ while ((c = getopt_long(argc, argv, "", long_options, &option_index)) != -1) {
+ switch (c) {
+ case 't':
+ num_threads = atoi(optarg);
+ break;
+ default:
+ break;
+ }
+ }
+ if (num_threads == -1) {
+ PERFETTO_ELOG("Usage: %s [--threads=N]", argv[0]);
+ return 1;
+ }
+
+ PERFETTO_LOG("Spawning %d threads.", num_threads);
+ for (int i = 0; i < num_threads; i++) {
+ std::thread th(BusyWait);
+ th.detach();
+ }
+ PERFETTO_LOG("Threads spawned, Ctrl-C to stop.");
+ while (sleep(600))
+ ;
+
+ return 0;
+}
+
+} // namespace
+} // namespace perfetto
+
+int main(int argc, char** argv) {
+ return perfetto::BusyThreadsMain(argc, argv);
+}
