liblog: clock_gettime, clock_getres and time benchmarks

Add local BM_time_clock_gettime_*, BM_time_clock_getres_* and
BM_time_time benchmarks.  Relates to the bionic benchmarks of
the same names, except adds CLOCK_MONOTONIC_RAW.  Added here for
developer convenience whenever updates to the liblog or logd
code base need integration testing.

ToDo: add liblog gTests that analyse the benchmark data to confirm
that the specified integrated device has vdso access to all the
pertinent clock sources.  Add liblog local benchmarks and tests to
measure the device clock drift of each possible liblog clock
source to help evaluate device configuration.

Test: liblog_benchmarks --benchmark_filter=BM_time*
Bug: 63737556
Bug: 69423514
Change-Id: Ibafe0880d976ef2b3885765f71e0ba6c99d56f2a

1 files changed, 60 insertions, 0 deletions

diff --git a/liblog/tests/liblog_benchmark.cpp b/liblog/tests/liblog_benchmark.cpp
index 706a0f6ae..c2f3f837a 100644
--- a/liblog/tests/liblog_benchmark.cpp
+++ b/liblog/tests/liblog_benchmark.cpp
@@ -19,6 +19,7 @@
 #include <poll.h>
 #include <sys/endian.h>
 #include <sys/socket.h>
+#include <sys/syscall.h>
 #include <sys/types.h>
 #include <unistd.h>
 
@@ -107,6 +108,65 @@ static void BM_clock_overhead(benchmark::State& state) {
 }
 BENCHMARK(BM_clock_overhead);
 
+static void do_clock_overhead(benchmark::State& state, clockid_t clk_id) {
+  timespec t;
+  while (state.KeepRunning()) {
+    clock_gettime(clk_id, &t);
+  }
+}
+
+static void BM_time_clock_gettime_REALTIME(benchmark::State& state) {
+  do_clock_overhead(state, CLOCK_REALTIME);
+}
+BENCHMARK(BM_time_clock_gettime_REALTIME);
+
+static void BM_time_clock_gettime_MONOTONIC(benchmark::State& state) {
+  do_clock_overhead(state, CLOCK_MONOTONIC);
+}
+BENCHMARK(BM_time_clock_gettime_MONOTONIC);
+
+static void BM_time_clock_gettime_MONOTONIC_syscall(benchmark::State& state) {
+  timespec t;
+  while (state.KeepRunning()) {
+    syscall(__NR_clock_gettime, CLOCK_MONOTONIC, &t);
+  }
+}
+BENCHMARK(BM_time_clock_gettime_MONOTONIC_syscall);
+
+static void BM_time_clock_gettime_MONOTONIC_RAW(benchmark::State& state) {
+  do_clock_overhead(state, CLOCK_MONOTONIC_RAW);
+}
+BENCHMARK(BM_time_clock_gettime_MONOTONIC_RAW);
+
+static void BM_time_clock_gettime_BOOTTIME(benchmark::State& state) {
+  do_clock_overhead(state, CLOCK_BOOTTIME);
+}
+BENCHMARK(BM_time_clock_gettime_BOOTTIME);
+
+static void BM_time_clock_getres_MONOTONIC(benchmark::State& state) {
+  timespec t;
+  while (state.KeepRunning()) {
+    clock_getres(CLOCK_MONOTONIC, &t);
+  }
+}
+BENCHMARK(BM_time_clock_getres_MONOTONIC);
+
+static void BM_time_clock_getres_MONOTONIC_syscall(benchmark::State& state) {
+  timespec t;
+  while (state.KeepRunning()) {
+    syscall(__NR_clock_getres, CLOCK_MONOTONIC, &t);
+  }
+}
+BENCHMARK(BM_time_clock_getres_MONOTONIC_syscall);
+
+static void BM_time_time(benchmark::State& state) {
+  while (state.KeepRunning()) {
+    time_t now;
+    now = time(&now);
+  }
+}
+BENCHMARK(BM_time_time);
+
 /*
  * Measure the time it takes to submit the android logging data to pstore
  */