[lttng-dev] No kernel tracer available

[Simon Marchi]

> Hello, I'm a student at Polytechnique Montreal and we are trying to use
> lttng on ubuntu(Ubuntu 14.04.2 LTS) but always encounter the same problem :
>
> "Error: Unable to list kernel events: Kernel tracer not available"
>
> This happens even though we are root using the command line : sudo su
>
> We reinstalled the packages multiples time for lttng.org and from this
> source : https://launchpad.net/~lttng/+archive/ubuntu/ppa/
>
> We are able to create a session but we can't enable event (kernel tracer not
> available) or start tracing (error : no channel found).
>
> If someone has advice on how to deal we this, it would be appreciated a lot.
>
> Thank you,
>
> -Francis R.
>
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>

Hi Francis,

I'll start with the obvious stuff. After the "enable-event" command
fails (btw, could you give the exact commands you run?), please check:

1. Is there an "lttng-sessiond" process owned by the root user active
(ps aux | grep lttng-sessiond) ?
2. Are the LTTng kernel modules loaded (lsmod | grep lttng) ?

If the answer to any of those two is no, you will need to investigate
why that is. Perhaps you could provide the output of "dpkg -l | grep
lttng" to see what you have installed exactly.

Simon