Merge "Atrace: support streaming data to stdout." am: 83a98b101c am: 78d4fb8e77
am: b134014110
* commit 'b1340141101a2528cb6680862aa9d88df491bc3d':
Atrace: support streaming data to stdout.
diff --git a/cmds/atrace/atrace.cpp b/cmds/atrace/atrace.cpp
index 0e77850..be9709a 100644
--- a/cmds/atrace/atrace.cpp
+++ b/cmds/atrace/atrace.cpp
@@ -26,6 +26,7 @@
#include <string.h>
#include <sys/sendfile.h>
#include <time.h>
+#include <unistd.h>
#include <zlib.h>
#include <binder/IBinder.h>
@@ -214,6 +215,9 @@
static const char* k_tracePath =
"/sys/kernel/debug/tracing/trace";
+static const char* k_traceStreamPath =
+ "/sys/kernel/debug/tracing/trace_pipe";
+
static const char* k_traceMarkerPath =
"/sys/kernel/debug/tracing/trace_marker";
@@ -732,6 +736,31 @@
setTracingEnabled(false);
}
+// Read data from the tracing pipe and forward to stdout
+static void streamTrace()
+{
+ char trace_data[4096];
+ int traceFD = open(k_traceStreamPath, O_RDWR);
+ if (traceFD == -1) {
+ fprintf(stderr, "error opening %s: %s (%d)\n", k_traceStreamPath,
+ strerror(errno), errno);
+ return;
+ }
+ while (!g_traceAborted) {
+ ssize_t bytes_read = read(traceFD, trace_data, 4096);
+ if (bytes_read > 0) {
+ write(STDOUT_FILENO, trace_data, bytes_read);
+ fflush(stdout);
+ } else {
+ if (!g_traceAborted) {
+ fprintf(stderr, "read returned %zd bytes err %d (%s)\n",
+ bytes_read, errno, strerror(errno));
+ }
+ break;
+ }
+ }
+}
+
// Read the current kernel trace and write it to stdout.
static void dumpTrace()
{
@@ -878,6 +907,10 @@
" --async_dump dump the current contents of circular trace buffer\n"
" --async_stop stop tracing and dump the current contents of circular\n"
" trace buffer\n"
+ " --stream stream trace to stdout as it enters the trace buffer\n"
+ " Note: this can take significant CPU time, and is best\n"
+ " used for measuring things that are not affected by\n"
+ " CPU performance, like pagecache usage.\n"
" --list_categories\n"
" list the available tracing categories\n"
);
@@ -889,6 +922,7 @@
bool traceStart = true;
bool traceStop = true;
bool traceDump = true;
+ bool traceStream = false;
if (argc == 2 && 0 == strcmp(argv[1], "--help")) {
showHelp(argv[0]);
@@ -903,6 +937,7 @@
{"async_stop", no_argument, 0, 0 },
{"async_dump", no_argument, 0, 0 },
{"list_categories", no_argument, 0, 0 },
+ {"stream", no_argument, 0, 0 },
{ 0, 0, 0, 0 }
};
@@ -969,6 +1004,9 @@
async = true;
traceStart = false;
traceStop = false;
+ } else if (!strcmp(long_options[option_index].name, "stream")) {
+ traceStream = true;
+ traceDump = false;
} else if (!strcmp(long_options[option_index].name, "list_categories")) {
listSupportedCategories();
exit(0);
@@ -994,8 +1032,10 @@
ok &= startTrace();
if (ok && traceStart) {
- printf("capturing trace...");
- fflush(stdout);
+ if (!traceStream) {
+ printf("capturing trace...");
+ fflush(stdout);
+ }
// We clear the trace after starting it because tracing gets enabled for
// each CPU individually in the kernel. Having the beginning of the trace
@@ -1005,7 +1045,7 @@
ok = clearTrace();
writeClockSyncMarker();
- if (ok && !async) {
+ if (ok && !async && !traceStream) {
// Sleep to allow the trace to be captured.
struct timespec timeLeft;
timeLeft.tv_sec = g_traceDurationSeconds;
@@ -1016,6 +1056,10 @@
}
} while (nanosleep(&timeLeft, &timeLeft) == -1 && errno == EINTR);
}
+
+ if (traceStream) {
+ streamTrace();
+ }
}
// Stop the trace and restore the default settings.