From: Benjamin Poirier <benjamin.poirier@polymtl.ca>
Date: Thu, 9 Jul 2009 19:13:56 +0000 (-0400)
Subject: Add members to LttTrace to support time adjustments
X-Git-Tag: v0.12.26~58
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=9c9bf2d4c123db7e0d53714410d642388c8ae8e9;p=lttv.git

Add members to LttTrace to support time adjustments

Adds a function to convert tsc values to nanoseconds.
Adds drift and offset members for linear clock correction.

Signed-off-by: Benjamin Poirier <benjamin.poirier@polymtl.ca>
---

diff --git a/ltt/trace.h b/ltt/trace.h
index 202def10..7d7d7122 100644
--- a/ltt/trace.h
+++ b/ltt/trace.h
@@ -41,6 +41,8 @@ struct LttTrace {
   uint64_t  start_freq;
   uint64_t  start_tsc;
   uint64_t  start_monotonic;
+  double    drift;
+  double    offset;
   LttTime   start_time;
   LttTime   start_time_from_tsc;
 
@@ -207,6 +209,8 @@ gint64 ltt_get_int(gboolean reverse_byte_order, gint size, void *data);
 
 guint64 ltt_get_uint(gboolean reverse_byte_order, gint size, void *data);
 
+guint64 tsc_to_uint64(guint32 freq_scale, uint64_t start_freq, guint64 tsc);
+
 LttTime ltt_interpolate_time_from_tsc(LttTracefile *tf, guint64 tsc);
 
 /* Set to enable event debugging output */
diff --git a/ltt/tracefile.c b/ltt/tracefile.c
index 1d6f2a86..2ac0fa58 100644
--- a/ltt/tracefile.c
+++ b/ltt/tracefile.c
@@ -171,10 +171,9 @@ static int parse_trace_header(ltt_subbuffer_header_t *header,
                                        &vheader->start_time_usec);
           t->start_time.tv_nsec *= 1000; /* microsec to nanosec */
 
-          t->start_time_from_tsc = ltt_time_from_uint64(
-              (double)t->start_tsc
-              * 1000000000.0 * tf->trace->freq_scale
-              / (double)t->start_freq);
+	  t->start_time_from_tsc =
+		  ltt_time_from_uint64(tsc_to_uint64(t->freq_scale,
+				  t->start_freq, t->start_tsc));
         }
       }
       break;
@@ -872,6 +871,8 @@ LttTrace *ltt_trace_open(const gchar *pathname)
   g_assert(!ret);
 
   t->num_cpu = group->len;
+  t->drift = 1.;
+  t->offset = 0.;
   
   //ret = allocate_marker_data(t);
   //if (ret)
@@ -1154,28 +1155,22 @@ fail:
   return 1;
 }
 
+/*
+ * Convert a value in "TSC scale" to a value in nanoseconds
+ */
+guint64 tsc_to_uint64(guint32 freq_scale, uint64_t start_freq, guint64 tsc)
+{
+	return (double) tsc * NANOSECONDS_PER_SECOND * freq_scale / start_freq;
+}
+
 /* Given a TSC value, return the LttTime (seconds,nanoseconds) it
  * corresponds to.
  */
-
 LttTime ltt_interpolate_time_from_tsc(LttTracefile *tf, guint64 tsc)
 {
-  LttTime time;
-  
-  if(tsc > tf->trace->start_tsc) {
-    time = ltt_time_from_uint64(
-        (double)(tsc - tf->trace->start_tsc) 
-                                    * 1000000000.0 * tf->trace->freq_scale
-                                    / (double)tf->trace->start_freq);
-    time = ltt_time_add(tf->trace->start_time_from_tsc, time);
-  } else {
-    time = ltt_time_from_uint64(
-        (double)(tf->trace->start_tsc - tsc)
-                                    * 1000000000.0 * tf->trace->freq_scale
-                                    / (double)tf->trace->start_freq);
-    time = ltt_time_sub(tf->trace->start_time_from_tsc, time);
-  }
-  return time;
+	return ltt_time_from_uint64(tsc_to_uint64(tf->trace->freq_scale,
+			tf->trace->start_freq, tf->trace->drift * tsc +
+			tf->trace->offset));
 }
 
 /* Calculate the real event time based on the buffer boundaries */