Understanding the timestamp of ltrace

[Pavel Kazlenka]

Hi Franck,

Please find some answers in-lined:

On 07/15/2013 09:15 PM, Franck Youssef wrote:
> Hello,
>
> I am trying to generate log traces of err_xact.count myself, using the polygraph-ltrace --objects.
>
> I would like to sample these values with a sampling interval of 20 seconds.
>
> To my understanding, that should be feasible with the --time_unit option. However, when running ltrace with different --time_unit values] I always obtain the same output.

> Furthermore, when printing the 'time' object using --time_unit 1s, I obtain some kind of a funny timestamp prefixed with a dash: "-2147483620.50"  (= Fri Dec 13 21:46:19 MET 1901 using date -d @…).

This seems like a bug. What polygraph version do you use?

> What does that timestamp mean, how could I obtain a "natural" unix timestamp and how could I modify the sampling interval?

You could modify sampling interval using '--win_len' option. Do not use 
'--time_unit' option if you want unix timestamps.
e.g.
$ polygraph-ltrace --objects time, err_xact.count --win_len 20sec <lo
> Best,
> Franck
>

Best wishes,
Pavel