| Message ID | 20210315061832.168495-11-tz.stoyanov@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | TSC trace clock to nanosecond conversion | expand |
On Mon, 15 Mar 2021 08:18:30 +0200 "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote: > 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. > I'll have to play with this a bit, but for now this looks fine. -- Steve
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c index dc9ac1d3..1cffa0f5 100644 --- a/lib/trace-cmd/trace-input.c +++ b/lib/trace-cmd/trace-input.c @@ -1224,21 +1224,12 @@ 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; @@ -1295,17 +1286,26 @@ static unsigned long long mul_u64_u32_shr(unsigned long long a, static unsigned long long timestamp_calc(unsigned long long ts, struct tracecmd_input *handle) { - unsigned long long t; + unsigned long long t = ts; - t = timestamp_correct(ts, handle); - if (handle->ts2secs) + /* Guest trace file, sync with host timestamps */ + if (handle->host.sync_enable) + t = timestamp_host_sync(ts, handle); + + if (handle->ts2secs) { + /* user specified clock frequency */ t *= handle->ts2secs; - else if (handle->tsc_calc.mult) { + } else if (handle->tsc_calc.mult) { + /* auto calculated TSC clock frequency */ t = mul_u64_u32_shr(t, handle->tsc_calc.mult, handle->tsc_calc.shift); t += handle->tsc_calc.offset; } + /* User specified time offset with --ts-offset or --date options */ + if (handle->ts_offset) + t += handle->ts_offset; + return t; }
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 | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-)