Avoid a system call in 'gettid'.
System calls can be pretty slow. This is mako, which has one of our
lowest latencies:
iterations ns/op
BM_unistd_getpid 10000000 209
BM_unistd_gettid 200000000 8
Bug: 15297299 (kernel panic from too many gettid calls)
Bug: 15315766 (excessive gettid overhead in liblogd)
Change-Id: I49656c0fc5b5d092390264a59e4f2c0d8a8b1aeb
diff --git a/benchmarks/unistd_benchmark.cpp b/benchmarks/unistd_benchmark.cpp
index e839bf8..12b788a 100644
--- a/benchmarks/unistd_benchmark.cpp
+++ b/benchmarks/unistd_benchmark.cpp
@@ -28,3 +28,14 @@
StopBenchmarkTiming();
}
BENCHMARK(BM_unistd_getpid);
+
+static void BM_unistd_gettid(int iters) {
+ StartBenchmarkTiming();
+
+ for (int i = 0; i < iters; ++i) {
+ gettid();
+ }
+
+ StopBenchmarkTiming();
+}
+BENCHMARK(BM_unistd_gettid);