#define max_t(type, a, b) ((type) ((a) > (b) ? (a) : (b)))
#endif
+#define NR_CLOCK_OFFSET_SAMPLES 10
+
+struct offset_sample {
+ uint64_t offset; /* correlation offset */
+ uint64_t measure_delta; /* lower is better */
+};
+
static inline
int fls(unsigned int x)
{
"};\n\n");
if (ret)
goto end;
+ event->metadata_dumped = 1;
end:
return ret;
ret = lttng_metadata_printf(session,
"};\n\n");
+ /* Flag success of metadata dump. */
+ chan->metadata_dumped = 1;
end:
return ret;
);
}
-/*
- * Approximation of NTP time of day to clock monotonic correlation,
- * taken at start of trace.
- * Yes, this is only an approximation. Yes, we can (and will) do better
- * in future versions.
- */
static
-uint64_t measure_clock_offset(void)
+int measure_single_clock_offset(struct offset_sample *sample)
{
- uint64_t offset, monotonic[2], realtime;
+ uint64_t offset, monotonic[2], measure_delta, realtime;
struct timespec rts = { 0, 0 };
int ret;
monotonic[0] = trace_clock_read64();
ret = clock_gettime(CLOCK_REALTIME, &rts);
- if (ret < 0)
- return 0;
+ if (ret < 0) {
+ return ret;
+ }
monotonic[1] = trace_clock_read64();
+ measure_delta = monotonic[1] - monotonic[0];
+ if (measure_delta > sample->measure_delta) {
+ /*
+ * Discard value if it took longer to read than the best
+ * sample so far.
+ */
+ return 0;
+ }
offset = (monotonic[0] + monotonic[1]) >> 1;
realtime = (uint64_t) rts.tv_sec * 1000000000ULL;
realtime += rts.tv_nsec;
offset = realtime - offset;
- return offset;
+ sample->offset = offset;
+ sample->measure_delta = measure_delta;
+ return 0;
}
+/*
+ * Approximation of NTP time of day to clock monotonic correlation,
+ * taken at start of trace. Keep the measurement that took the less time
+ * to complete, thus removing imprecision caused by preemption.
+ */
+static
+uint64_t measure_clock_offset(void)
+{
+ int i;
+ struct offset_sample offset_best_sample = {
+ .offset = 0,
+ .measure_delta = UINT64_MAX,
+ };
+
+ for (i = 0; i < NR_CLOCK_OFFSET_SAMPLES; i++) {
+ if (measure_single_clock_offset(&offset_best_sample)) {
+ return 0;
+ }
+ }
+ return offset_best_sample.offset;
+}
/*
* Should be called with session registry mutex held.
*/
int ust_metadata_session_statedump(struct ust_registry_session *session,
- struct ust_app *app)
+ struct ust_app *app,
+ uint32_t major,
+ uint32_t minor)
{
unsigned char *uuid_c;
char uuid_s[UUID_STR_LEN],
int ret = 0;
char hostname[HOST_NAME_MAX];
+ assert(session);
+
uuid_c = session->uuid;
snprintf(uuid_s, sizeof(uuid_s),
" domain = \"ust\";\n"
" tracer_name = \"lttng-ust\";\n"
" tracer_major = %u;\n"
- " tracer_minor = %u;\n"
- " tracer_patchlevel = %u;\n"
- "};\n\n",
+ " tracer_minor = %u;\n",
hostname,
- app->version.major,
- app->version.minor,
- app->version.patchlevel
+ major,
+ minor
);
if (ret)
goto end;
*/
if (app) {
ret = lttng_metadata_printf(session,
+ " tracer_patchlevel = %u;\n"
" vpid = %d;\n"
- " procname = \"%s\";\n"
- "};\n\n",
+ " procname = \"%s\";\n",
+ app->version.patchlevel,
(int) app->pid,
app->name
);