Fix: --clock-force-correlate to handle trace collections gathered from various nodes

Currently, traces generated by lttng have the "absolute" flag set to 0,
because they are based on the monotonic clock, which is not perfectly
correlated across nodes.

Fix a couple of minor issue in the handling of --clock-force-correlate
that now allow to use it to force correlation of traces taken with the
monotonic clock source, with "offset" approximation populated using NTP
time.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/formats/ctf/ctf.c b/formats/ctf/ctf.c
index a2403a77ab8d8906e18e59cb41d6a68684e2ba7a..f43fe91789d21d109c0adf407a0b7e951201ca39 100644 (file)
--- a/formats/ctf/ctf.c
+++ b/formats/ctf/ctf.c
@@ -1517,7 +1517,7 @@ int ctf_open_file_stream_read(struct ctf_trace *td, const char *path, int flags,
        if (ret)
                goto error_def;
        /*
-        * For now, only a single slock is supported.
+        * For now, only a single clock per trace is supported.
         */
        file_stream->parent.current_clock = td->single_clock;
        ret = create_stream_packet_index(td, file_stream);
@@ -1746,7 +1746,7 @@ int ctf_open_mmap_stream_read(struct ctf_trace *td,
                goto error_index;
 
        /*
-        * For now, only a single slock is supported.
+        * For now, only a single clock per trace is supported.
         */
        file_stream->parent.current_clock = td->single_clock;
 

diff --git a/formats/ctf/events-private.h b/formats/ctf/events-private.h
index 6208e563d2315f94994f88c183041bacc8d3d65c..a3caf7aed9092796e2e79e95b999a678c5d45baf 100644 (file)
--- a/formats/ctf/events-private.h
+++ b/formats/ctf/events-private.h
@@ -33,7 +33,12 @@ uint64_t ctf_get_real_timestamp(struct ctf_stream_definition *stream,
        uint64_t ts_nsec;
        struct ctf_trace *trace = stream->stream_class->trace;
        struct trace_collection *tc = trace->collection;
-       uint64_t tc_offset = tc->single_clock_offset_avg;
+       uint64_t tc_offset;
+
+       if (tc->clock_use_offset_avg)
+               tc_offset = tc->single_clock_offset_avg;
+       else
+               tc_offset = trace->single_clock->offset;
 
        ts_nsec = clock_cycles_to_ns(stream->current_clock, timestamp);
        ts_nsec += tc_offset;   /* Add offset */

diff --git a/formats/ctf/metadata/ctf-visitor-generate-io-struct.c b/formats/ctf/metadata/ctf-visitor-generate-io-struct.c
index 500482f57f03f5c77b445dc92938a12b4fe779c2..43fdcb22442386cace3e60553842e3b5c7eabd82 100644 (file)
--- a/formats/ctf/metadata/ctf-visitor-generate-io-struct.c
+++ b/formats/ctf/metadata/ctf-visitor-generate-io-struct.c
@@ -2360,7 +2360,7 @@ int ctf_clock_visit(FILE *fd, int depth, struct ctf_node *node, struct ctf_trace
        }
        if (!CTF_CLOCK_FIELD_IS_SET(clock, name)) {
                ret = -EPERM;
-               fprintf(fd, "[error] %s: missing namefield in clock declaration\n", __func__);
+               fprintf(fd, "[error] %s: missing name field in clock declaration\n", __func__);
                goto error;
        }
        if (g_hash_table_size(trace->clocks) > 0) {

diff --git a/include/babeltrace/babeltrace-internal.h b/include/babeltrace/babeltrace-internal.h
index 2137c23f5e74c9c941fc5b16671633d489d7f038..29354a4a0eaa5f4503fec218c2aa0489a042d308 100644 (file)
--- a/include/babeltrace/babeltrace-internal.h
+++ b/include/babeltrace/babeltrace-internal.h
@@ -46,6 +46,7 @@ struct trace_collection {
        uint64_t offset_first;
        int64_t delta_offset_first_sum;
        int offset_nr;
+       int clock_use_offset_avg;
 };
 
 extern int opt_all_field_names,

diff --git a/lib/trace-collection.c b/lib/trace-collection.c
index 1c78f280fe0bcb128d3da85dbdfdf5a0e5daa6b4..9b60986f5018e98c54e870c471cf498d36d79839 100644 (file)
--- a/lib/trace-collection.c
+++ b/lib/trace-collection.c
@@ -39,24 +39,24 @@ static void check_clock_match(gpointer key, gpointer value, gpointer user_data)
        struct clock_match *match = user_data;
        struct ctf_clock *clock_a = value, *clock_b;
 
-       if (clock_a->uuid != 0) {
+       if (clock_a->absolute) {
                /*
-                * Lookup the the trace clocks into the collection
-                * clocks.
+                * Absolute time references, such as NTP, are looked up
+                * by clock name.
                 */
                clock_b = g_hash_table_lookup(match->clocks,
-                       (gpointer) (unsigned long) clock_a->uuid);
+                       (gpointer) (unsigned long) clock_a->name);
                if (clock_b) {
                        match->clock_match = clock_b;
                        return;
                }
-       } else if (clock_a->absolute) {
+       } else if (clock_a->uuid != 0) {
                /*
-                * Absolute time references, such as NTP, are looked up
-                * by clock name.
+                * Lookup the the trace clocks into the collection
+                * clocks.
                 */
                clock_b = g_hash_table_lookup(match->clocks,
-                       (gpointer) (unsigned long) clock_a->name);
+                       (gpointer) (unsigned long) clock_a->uuid);
                if (clock_b) {
                        match->clock_match = clock_b;
                        return;
@@ -95,8 +95,9 @@ static void clock_add(gpointer key, gpointer value, gpointer user_data)
                                (gpointer) (unsigned long) v);
                if (!tc_clock) {
                        /*
-                        * For now, we only support CTF that has one
-                        * single clock uuid or name (absolute ref).
+                        * For now we only support CTF that has one
+                        * single clock uuid or name (absolute ref) per
+                        * trace.
                         */
                        if (g_hash_table_size(tc_clocks) > 0) {
                                fprintf(stderr, "[error] Only CTF traces with a single clock description are supported by this babeltrace version.\n");
@@ -111,12 +112,13 @@ static void clock_add(gpointer key, gpointer value, gpointer user_data)
                        g_hash_table_insert(tc_clocks,
                                (gpointer) (unsigned long) v,
                                value);
-               } else {
+               } else if (!t_clock->absolute) {
                        int64_t diff_ns;
 
                        /*
-                        * Check that the offsets match. If not, warn
-                        * the user that we do an arbitrary choice.
+                        * For non-absolute clocks, check that the
+                        * offsets match. If not, warn the user that we
+                        * do an arbitrary choice.
                         */
                        diff_ns = clock_offset_ns(tc_clock) - clock_offset_ns(t_clock);
                        printf_debug("Clock \"%s\" offset between traces has a delta of %" PRIu64 " ns.",
@@ -134,6 +136,8 @@ static void clock_add(gpointer key, gpointer value, gpointer user_data)
                        clock_match->tc->single_clock_offset_avg =
                                clock_match->tc->offset_first
                                + (clock_match->tc->delta_offset_first_sum / clock_match->tc->offset_nr);
+                       /* Time need to use offset average */
+                       clock_match->tc->clock_use_offset_avg = 1;
                }
        }
 }