Send lttng-dev mailing list submissions to
lttng-dev@lists.lttng.org
To subscribe or unsubscribe via the World Wide Web, visit
https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
or, via email, send a message with subject or body 'help' to
lttng-dev-request@lists.lttng.org
You can reach the person managing the list at
lttng-dev-owner@lists.lttng.org
When replying, please edit your Subject line so it is more specific
than "Re: Contents of lttng-dev digest..."
Today's Topics:
1. Re: Can't trace function calls (Jonathan Rajotte-Julien)
----------------------------------------------------------------------
Message: 1
Date: Fri, 2 Apr 2021 11:07:19 -0400
From: Jonathan Rajotte-Julien <jonathan.rajotte-julien@efficios.com>
To: Ramesh Errabolu <ramesh.errabolu@gmail.com>
Cc: lttng-dev@lists.lttng.org
Subject: Re: [lttng-dev] Can't trace function calls
Message-ID: <20210402150719.GB79283@joraj-alpa>
Content-Type: text/plain; charset=us-ascii
On Wed, Mar 31, 2021 at 12:55:53PM -0500, Ramesh Errabolu wrote:
> root@RocrLnx23:~/git/compute/out/ubuntu-18.04/18.04/bin# ls ~/ | grep -i ltt
> root@RocrLnx23:~/git/compute/out/ubuntu-18.04/18.04/bin# lttng create
> my-kernel-session --output=~/my-kernel-trace
> Session my-kernel-session created.
> Traces will be output to
> /home/user1/git/compute/out/ubuntu-18.04/18.04/bin/~/my-kernel-trace
> root@RocrLnx23:~/git/compute/out/ubuntu-18.04/18.04/bin# *lttng list
> --kerne*l
> *Error: Unable to list kernel events: Kernel tracer not available*
Well this would be the first thing to look at.
First let's deactivate the lttng-sessiond.service installed by the packages.
systemctl stop lttng-sessiond.service
You might want to reanable it later.
>
> root@RocrLnx23:~/git/compute/out/ubuntu-18.04/18.04/bin# ps -ef | grep ltt
> root 1002 1 0 12:16 ? 00:00:00 /usr/bin/lttng-sessiond
> root 1054 1002 0 12:16 ? 00:00:00 */usr/bin/lttng-sessiond*
> root 3145 2861 0 12:51 pts/0 00:00:00 grep --color=auto ltt
> root@RocrLnx23:~/git/compute/out/ubuntu-18.04/18.04/bin#
Make sure after the systemctl call that no lttng-sessiond process is running.
Now let's launch a lttng-sessiond by hand with a bit more verbosity. For now
let's stick to the root user.
# lttng-sessiond -vvv --verbose-consumer -b > /tmp/lttng-sessiond.log 2>&1
# pkill lttng-sessiond
Please share the content of /tmp/lttng-sessiond.log using a pasting service
(paste.ubuntu.com).
Also please provide the output of:
# uname -a
# find /lib/modules/$(uname -r)/ | grep lttng
# dmesg | grep lttng
But again, the cyg-profile helper library is meant for Userspace tracing.
With the app running and having the LD_PRELOAD correctly set, and a sessiond
running.
# lttng list -u
If there is nothing, well you can start the application with the following and
share the output of it (make sure to remove any output from your application if
sensitive data is present)
# LD_PRELOAD=.... LTTNG_UST_DEBUG=1 your_application_here
Note that debug log will be outputted on stderr.
Cheers
--
Jonathan Rajotte-Julien
EfficiOS
------------------------------
Subject: Digest Footer
_______________________________________________
lttng-dev mailing list
lttng-dev@lists.lttng.org
https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
------------------------------
End of lttng-dev Digest, Vol 156, Issue 3
*****************************************