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From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org
Subject: [PATCH v4 15/23] trace-cmd: Set order and priorities when applying timestamp corrections
Date: Thu, 25 Mar 2021 08:40:47 +0200
Message-ID: <20210325064055.539554-16-tz.stoyanov@gmail.com> (raw)
In-Reply-To: <20210325064055.539554-1-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


  parent reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-25  6:40 [PATCH v4 00/23] TSC trace clock to nanosecond conversion Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 01/23] trace-cmd: Add initial perf interface in trace-cmd library Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 02/23] trace-cmd: Extend trace-cmd dump subcommand to display the clock Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 03/23] trace-cmd: Save only the selected clock in the trace.dat file Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 04/23] trace-cmd: Internal refactoring, move logic for local tep handler in its own function Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 05/23] trace-cmd: Add new local function to check if a trace clock is supported Tzvetomir Stoyanov (VMware)
2021-03-26 21:21   ` Steven Rostedt
2021-03-25  6:40 ` [PATCH v4 06/23] trace-cmd: Add new trace-cmd clock tsc2nsec Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 07/23] trace-cmd: Define a new option for tsc2nsec conversion Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 08/23] trace-cmd: Save information for tsc to nanoseconds conversion in trace file Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 09/23] trace-cmd: Read information for tsc to nanoseconds conversion from " Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 10/23] trace-cmd: Save tsc2nsec clock in trace.dat file Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 11/23] trace-cmd: Append new options into guest trace file at the end of the tracing session Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 12/23] trace-cmd: Remove unneeded multiply in events timestamp reading Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 13/23] trace-cmd: Perform all timestamp corrections in a single function Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 14/23] trace-cmd: Convert tsc timestamps to nanosecods when reading trace data from a file Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` Tzvetomir Stoyanov (VMware) [this message]
2021-03-25  6:40 ` [PATCH v4 16/23] trace-cmd: Add a new flag to disable any timestamp corrections Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 17/23] trace-cmd: Change "--nodate" option to affect "--date" option only Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 18/23] trace-cmd: Add new parameter "--raw-ts" to "trace-cmd report" command Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 19/23] trace-cmd: Print times in TimeShift options as unsigned in trace-cmd dump Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 20/23] trace-cmd: Use tsc clock for host-guest tracing, if available Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 21/23] trace-cmd: Get current clock for host-guest tracing session Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 22/23] trace-cmd: Save the trace clocks in TRACECLOCK option Tzvetomir Stoyanov (VMware)
2021-03-25  6:40 ` [PATCH v4 23/23] trace-cmd: Read at least 8 bytes trace-id option Tzvetomir Stoyanov (VMware)
2021-03-26 21:18   ` Steven Rostedt

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