Adding system property tracing
Introducing a new systrace tag, TRACE_TAG_SYSPROP, for use with
system property.
For property set, the tracing is added in __system_property_set() instead of
__system_property_update() / __system_property_add() so we can record
control properties like ctl.*, sys.powerctl.*, etc.., which won't be
updated via the latter two functions.
Bug: 147275573
Test: atest CtsBionicTestCases
Test: adb shell perfetto -o /data/misc/perfetto-traces/test_trace -t 10s bionic
Test: adb shell perfetto -o /data/misc/perfetto-traces/test_trace -t 10s sysprop
Test: adb shell /data/benchmarktest64/bionic-benchmarks/bionic-benchmarks \
--benchmark_filter=BM_property --bionic_cpu=4, then compares the results
of property benchmarks before and after the change, didn't see
significant difference.
Change-Id: Id2b93acb2ce02b308c0e4889f836159151af3b46
Merged-In: Id2b93acb2ce02b308c0e4889f836159151af3b46
(cherry picked from commit 26970c34937e2339876d6ba335a56769d6f0d75e)
diff --git a/libc/bionic/bionic_systrace.cpp b/libc/bionic/bionic_systrace.cpp
index fd97712..06f4505 100644
--- a/libc/bionic/bionic_systrace.cpp
+++ b/libc/bionic/bionic_systrace.cpp
@@ -14,36 +14,41 @@
* limitations under the License.
*/
+#include "private/bionic_systrace.h"
+
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
-#include "private/bionic_lock.h"
-#include "private/bionic_systrace.h"
-#include "private/CachedProperty.h"
-
#include <async_safe/log.h>
#include <cutils/trace.h> // For ATRACE_TAG_BIONIC.
+#include "private/CachedProperty.h"
+#include "private/bionic_lock.h"
+
#define WRITE_OFFSET 32
static Lock g_lock;
-static CachedProperty g_debug_atrace_tags_enableflags("debug.atrace.tags.enableflags");
static uint64_t g_tags;
static int g_trace_marker_fd = -1;
-static bool should_trace() {
- g_lock.lock();
- if (g_debug_atrace_tags_enableflags.DidChange()) {
- g_tags = strtoull(g_debug_atrace_tags_enableflags.Get(), nullptr, 0);
- }
- g_lock.unlock();
- return ((g_tags & ATRACE_TAG_BIONIC) != 0);
+static CachedProperty& GetTagsProp() {
+ static CachedProperty cached_property(kTraceTagsProp);
+ return cached_property;
}
-static int get_trace_marker_fd() {
+bool should_trace(const uint64_t enable_tags) {
+ g_lock.lock();
+ if (GetTagsProp().DidChange()) {
+ g_tags = strtoull(GetTagsProp().Get(), nullptr, 0);
+ }
+ g_lock.unlock();
+ return g_tags & enable_tags;
+}
+
+int get_trace_marker_fd() {
g_lock.lock();
if (g_trace_marker_fd == -1) {
g_trace_marker_fd = open("/sys/kernel/tracing/trace_marker", O_CLOEXEC | O_WRONLY);
@@ -55,11 +60,8 @@
return g_trace_marker_fd;
}
-void bionic_trace_begin(const char* message) {
- if (!should_trace()) {
- return;
- }
-
+// event could be 'B' for begin or 'E' for end.
+void output_trace(const char* message, const char event) {
int trace_marker_fd = get_trace_marker_fd();
if (trace_marker_fd == -1) {
return;
@@ -69,13 +71,22 @@
// kernel trace_marker.
int length = strlen(message);
char buf[length + WRITE_OFFSET];
- size_t len = async_safe_format_buffer(buf, length + WRITE_OFFSET, "B|%d|%s", getpid(), message);
+ size_t len =
+ async_safe_format_buffer(buf, length + WRITE_OFFSET, "%c|%d|%s", event, getpid(), message);
// Tracing may stop just after checking property and before writing the message.
// So the write is acceptable to fail. See b/20666100.
TEMP_FAILURE_RETRY(write(trace_marker_fd, buf, len));
}
+void bionic_trace_begin(const char* message) {
+ if (!should_trace()) {
+ return;
+ }
+
+ output_trace(message);
+}
+
void bionic_trace_end() {
if (!should_trace()) {
return;