[PATCH v4 15/23] trace-cmd: Set order and priorities when applying timestamp corrections

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

There are multiple options that affect the event's timestamps while
recording trace or displaying the trace file. Some of these options can
be used together and the order and priorities for all of them should be
strictly defined:
 trace-cmd record --date , --ts-offset - only one of these can be used
 trace-cmd record host-guest trace - guest timestamps are auto
synchronized with host time stamps. If no trace clock is set by the user
and "kvm" synch plugin is available, then "x86-tsc" trace clock is used
and tsc timestamps are converted to nanoseconds in both host and guest
trace events.
 trace-cmd report --ts-offset, --ts2secs, --nodate

Event timestamps corrections are applied in this order, when the trace
file is opened for reading:
 1. If it is a guest trace file and there is information for
    synchronization with the host events and is this synchronization is
    enabled: synchronize guest events with host events.
 2. If the user has specified --ts2secs, apply it.
 3. If the user has not specified --ts2secs and there is information in
    the trace file metadata for tsc to nanosecond conversion, apply it.
 4. If the user has specified --ts-offset or --date, apply it. The
    offsets specified by "report" command have higher priority that the
    offsets specified by "record" command.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/trace-input.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 266b0b0c..696e7bd8 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -1241,21 +1241,12 @@ timestamp_correction_calc(unsigned long long ts, unsigned int flags,
 	return ts + tscor;
 }
 
-static unsigned long long timestamp_correct(unsigned long long ts,
-					    struct tracecmd_input *handle)
+static unsigned long long timestamp_host_sync(unsigned long long ts,
+					      struct tracecmd_input *handle)
 {
 	struct host_trace_info	*host = &handle->host;
 	int min, mid, max;
 
-	if (handle->flags & TRACECMD_FL_IGNORE_DATE)
-		return ts;
-
-	if (handle->ts_offset)
-		return ts + handle->ts_offset;
-
-	if (!host->sync_enable)
-		return ts;
-
 	/* We have one sample, nothing to calc here */
 	if (host->ts_samples_count == 1)
 		return ts + host->ts_samples[0].offset;
@@ -1296,15 +1287,23 @@ static unsigned long long timestamp_correct(unsigned long long ts,
 static unsigned long long timestamp_calc(unsigned long long ts,
 					 struct tracecmd_input *handle)
 {
-	ts = timestamp_correct(ts, handle);
+	/* Guest trace file, sync with host timestamps */
+	if (handle->host.sync_enable)
+		ts = timestamp_host_sync(ts, handle);
 
-	if (handle->ts2secs)
+	if (handle->ts2secs) {
+		/* user specified clock frequency */
 		ts *= handle->ts2secs;
-	else if (handle->tsc_calc.mult) {
+	} else if (handle->tsc_calc.mult) {
+		/* auto calculated TSC clock frequency */
 		ts -= handle->tsc_calc.offset;
 		ts = mul_u64_u32_shr(ts, handle->tsc_calc.mult, handle->tsc_calc.shift);
 	}
 
+	/* User specified time offset with --ts-offset or --date options */
+	if (handle->ts_offset)
+		ts += handle->ts_offset;
+
 	return ts;
 }
 
-- 
2.30.2