Hello, 

We are writing to you regarding an issue we encountered while attempting to trace Ceph with LTTng-UST. Below are the steps we have followed so far:

1. Compiling Ceph with LTTng Support:

   • We modified the debian/rules file to enable LTTng support using the following flags: -DWITH_LTTNG=ON and -DWITH_OSD_INSTRUMENT_FUNCTIONS=ON.
   • The compilation process took approximately 7 hours on a virtual machine running Debian 12 with a kernel version 6.1.0-27-amd64, 8 GB of RAM, and 2 CPU cores.
   • The build steps can be found in our GitHub repository.

2. Deploying a Ceph Cluster:

   • We deployed the cluster manually (1MON,1MGR,2OSDs). Please find the script here.

3. Attempting to Trace with LTTng-UST:

   • We tried listing the tracepoints using the following command :

   # lttng list -u

   • This command did not return any Ceph-related tracepoints:

   UST events:
   -------------
   NONE

4. Preloading liblttng-ust-fork.so:

• We attempted to preload liblttng-ust-fork.so before starting the Ceph daemons (MON, OSD, MGR) as follows:

# systemctl edit ceph-mon@debian

• We added the following configuration:

[Service]
Environment="LD_PRELOAD=/usr/lib/x86_64-linux-gnu/liblttng-ust-fork.so

• After restarting the daemons, we executed lttng list -u, which displayed tracepoints related to the libraries (lttng_ust_lib:*), trace logs (lttng_ust_tracelog:*), and state dump events (lttng_ust_statedump:*), instead of the expected Ceph-related tracepoints.

Expected Result:

UST events:  
-------------  
PID: 100859 - Name: /path/to/ceph-osd  
    pg:queue_op (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)  
    osd:do_osd_op_post (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)  
    osd:do_osd_op_pre_unknown (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)  
    osd:do_osd_op_pre_copy_from (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)  
    osd:do_osd_op_pre_copy_get (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)  
    ...  

Actual Result:
UST events:
-------------
lttng_ust_lib:*
lttng_ust_tracelog:*
lttng_ust_statedump:*

We would greatly appreciate any help  you could provide to resolve this problem.