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Commit fe8c96d1 authored by Mark Salyzyn's avatar Mark Salyzyn
Browse files

liblog: benchmark add BM_log_event_overhead_42 for a well known tag 

Measure the cost of using a known test event log tag from
system/core/logcat/event.logtags:

42    answer (to life the universe etc|3)

Test: liblog_benchmarks BM_log_event_overhead_42
Bug: 36683634
Change-Id: Ibd4be82bebfcedd381c84e8078cf6d05a636aa98
parent cf29755e

liblog/tests/liblog_benchmark.cpp

+25 −1
Original line number Diff line number Diff line
@@ -527,11 +527,13 @@ BENCHMARK(BM_log_print_overhead); 
/*

 *	Measure the time it takes to submit the android event logging call

 * using discrete acquisition (StartBenchmarkTiming() -> StopBenchmarkTiming())

 * under light load. Expect this to be a dozen or so syscall periods (40us)

 * under light load. Expect this to be a long path to logger to convert the

 * unknown tag (0) into a tagname (less than 200us).

 */

static void BM_log_event_overhead(int iters) {

  for (unsigned long long i = 0; i < (unsigned)iters; ++i) {

    StartBenchmarkTiming();

    // log tag number 0 is not known, nor shall it ever be known

    __android_log_btwrite(0, EVENT_TYPE_LONG, &i, sizeof(i));

    StopBenchmarkTiming();

    logd_yield();
@@ -539,6 +541,28 @@ static void BM_log_event_overhead(int iters) { 
}

BENCHMARK(BM_log_event_overhead);



/*

 *	Measure the time it takes to submit the android event logging call

 * using discrete acquisition (StartBenchmarkTiming() -> StopBenchmarkTiming())

 * under light load with a known logtag.  Expect this to be a dozen or so

 * syscall periods (less than 40us)

 */

static void BM_log_event_overhead_42(int iters) {

  for (unsigned long long i = 0; i < (unsigned)iters; ++i) {

    StartBenchmarkTiming();

    // In system/core/logcat/event.logtags:

    // # These are used for testing, do not modify without updating

    // # tests/framework-tests/src/android/util/EventLogFunctionalTest.java.

    // # system/core/liblog/tests/liblog_benchmark.cpp

    // # system/core/liblog/tests/liblog_test.cpp

    // 42    answer (to life the universe etc|3)

    __android_log_btwrite(42, EVENT_TYPE_LONG, &i, sizeof(i));

    StopBenchmarkTiming();

    logd_yield();

  }

}

BENCHMARK(BM_log_event_overhead_42);



static void BM_log_event_overhead_null(int iters) {

  set_log_null();

  BM_log_event_overhead(iters);

logcat/event.logtags

+2 −0
Original line number Diff line number Diff line
@@ -36,6 +36,8 @@ 


# These are used for testing, do not modify without updating

# tests/framework-tests/src/android/util/EventLogFunctionalTest.java.

# system/core/liblog/tests/liblog_benchmark.cpp

# system/core/liblog/tests/liblog_test.cpp

42    answer (to life the universe etc|3)

314   pi

2718  e