[lttng-dev] LTTng Time Stamp Issue

[Jérémie Galarneau]

Hi,

I'm adding the LTTng mailing list in CC for the benefit of the community
and so people add to or correct my explanation.

The CTF specification describes the meaning of those fields:
http://diamon.org/ctf/#spec8

In your case, this means that the timestamps in the trace are expressed
relative to an arbitrary time set 1524226572435601778 clock ticks after
00:00:00 on 1 January 1970.

To take your specific example:
Your clock is running at 1,000,000,000 Hz, meaning the duration of a clock
tick (period) is of 1 ns.

The event has occurred at
1524226572435601778 (offset) + 00000003827855360941 (event clock value)
nanoseconds after UNIX Epoch. That leads us to around Friday, April 20,
2018 1:20:00 PM (GMT).

Regards,
Jérémie



On 20 April 2018 at 11:06, Sai Tujala <Sai.Tujala at mathworks.in> wrote:

> Hi Jeremie,
>
>
>
>                 In metadata file of LTTng trace session,  offset from
> Epoch is “1524226572435601778” and time stamp of an event in channel data
> files is starting from “00000003827855360941”. Can you brief about
> relevance between these two time stamps.
>
>
>
> freq = 1000000000; /* Frequency, in Hz */
>
>         /* clock value offset from Epoch is: offset * (1/freq) */
>
>         offset = 1524226572435601778;
>
>
>
>
>
> Thanks & Regards,
>
> T Sai Kiran
>
>
>



-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com
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