rtems-record-lttng: Corrupted timestamps after translating to CTF

[Joel Sherrill]

On Fri, Mar 5, 2021 at 10:45 AM Sebastian Huber <
sebastian.huber at embedded-brains.de> wrote:

> On 05/03/2021 16:11, Jan.Sommer at dlr.de wrote:
>
> > Some of the resulting CTF events have a very large timestamp. This only
> occurs for events of which are created by CPUs other than CPU0, but not all
> of them.
> > I ran rtems-record-lttng in gdb and could track it to
> record-client.c:176 (
> https://git.rtems.org/rtems-tools/tree/trace/record/record-client.c#n176).
> > There the (delta * ctx->to_bt_scaler ) causes an overflow and sets
> per_cpu->uptime.bt to a very large negative number which then later
> becomes a very large (positive) timestamp.
> >
> > I have some trouble figuring out what is going wrong here. The
> timestamps which are read from the rtems record events looks quite
> reasonable to me.
> > The to_bt_scaler is quite a large value and I don't fully get what it
> scales. Does someone have some hints?
> It could be related to ring buffer overflows. Do you get
> RTEMS_RECORD_PER_CPU_OVERFLOW items? There could be also some bugs in
> record-client.c. More unit tests for it would be helpful.
>

Asking stupidly, are there tests now? We didn't catch that libtrace was
missing in the new coverage reports:

https://ftp.rtems.org/pub/rtems/people/joel/coverage/coverage-2021-02-28/

I can add it to the queue that libtrace is added. If more subsystems
are missing that we want to track coverage on, please point them out.

--joel

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