Files
openairinterface5g/common/utils/LOG/DOC/lttng_logs.md
Robert Schmidt 8107939f08 Change OAI license to CSSL v1.0 (and others)
- all RAN code, CI code, configuration files, dockerfiles, in CSSL v1.0
- all deployment code (openshift, charts, ancillary files like shell
  scripts), in MIT
- documentation in CC-BY-4.0
- exceptions might apply and are listed in NOTICE
- there is a new LICENSES folder with all licenses
- CONTRIBUTIONS.md has been updated accordingly

For automated changes based on OAI PL v1.1:

    perl -i~ -0pe 's/\/\*.*Licensed to the OpenAirInterface.*openairinterface.org\n#?/\/*\n * SPDX-License-Identifier: LicenseRef-CSSL-1.0\n/s' **/*.{c,h,cpp}
    perl -i~ -0pe 's/\/\*.*Licensed to the OpenAirInterface.*openairinterface.org\n#?/\/*\n * SPDX-License-Identifier: LicenseRef-CSSL-1.0\n/s' **/*.ts
    perl -i~ -0pe 's/<!--.*Licensed to the OpenAirInterface.*openairinterface.org\n.*-->/<!-- SPDX-License-Identifier: LicenseRef-CSSL-1.0 -->/s' **/*.xml

The rest (cmake, files with missing license, cmake) manually.
2026-03-27 16:36:37 +01:00

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3.7 KiB
Markdown

<!-- SPDX-License-Identifier: CC-BY-4.0 -->
# OAI gNB LTTng Tracing Setup Guide
## Overview
This guide will walk you through setting up tracing for an OpenAirInterface (OAI) gNB (gNodeB) using LTTng (Linux Trace Toolkit Next Generation) and Babeltrace.
### What is LTTng and Why Use It?
LTTng, or Linux Trace Toolkit Next Generation, is a powerful logging framework designed for Linux systems. It provides low-overhead tracing capabilities, allowing developers to monitor and analyze system behavior in real-time without significant performance impact. LTTng offers several advantages:
- **Low Overhead**: LTTng introduces minimal overhead to the system, making it suitable for use in production environments without affecting system performance.
- **Customizable**: LTTng allows users to define custom tracepoints in their applications, providing fine-grained control over what events to trace and collect.
- **Scalability**: It can scale to large distributed systems, making it suitable for tracing complex software stacks across multiple nodes.
## Prerequisites
- Ubuntu system
Note: only LTTng 2.3.8 is supported.
## Building OAI gNB
1. **Clean and Build OAI gNB with LTTng:**
1.1 Install Dependencies
```bash
./build_oai --ninja -I --clean --enable-LTTNG
```
1.2 Build gNB and nrUE
```
./build_oai --ninja --gNB --nrUE -w SIMU --enable-LTTNG
```
## Setting up LTTng
1. **Start LTTng Session and Relay:**
```bash
sudo lttng-sessiond -d
sudo lttng-relayd -d
```
2. **Create Live LTTng Session:**
```bash
sudo lttng create my-session --live --set-url=net://127.0.0.1
```
3. **Enable gNB Trace Events:**
```bash
sudo lttng enable-event --userspace OAI:gNB
```
4. **Start LTTng Tracing:**
```bash
sudo lttng start
```
## Running the gNB
1. **Run gNB:**
```bash
./$binary_path -O $configuration_file PARALLEL_SINGLE_THREAD --rfsimulator.[0].serveraddr server --rfsim -E
```
## Verifying Tracepoints
1. **List Active Tracepoints:**
```bash
sudo lttng list -u
```
*Possible Output:*
```
UST events:
-------------
PID: 1154722 - Name: /home/firecell/Desktop/FirecellRepos/firecellrd-oai5g-ran/cmake_targets/ran_build/build/nr-softmodem
OAI:gNB (loglevel: TRACE_DEBUG_FUNCTION (12)) (type: tracepoint)
```
## Analyzing Traces
1. **Install Babeltrace:**
```bash
sudo apt-get install babeltrace
```
2. **Capture Trace Logs Live:**
- To learn the full path of the trace session:
```bash
babeltrace --input-format=lttng-live net://localhost
```
- Trace logs using the full path:
```bash
babeltrace --input-format=lttng-live net://localhost/host/firecell-XPS-15-9530/my-session
```
*Possible Output:*
```
[19:35:32.181608002] (+2.664882127) firecell-XPS-15-9530 OAI:gNB: { cpu_id = 10 }, { MODNAME = "OAI-NR_MAC info", EVENTID = -1, SFN = -1, SLOT = -1, FUNCTION = "gNB_dlsch_ulsch_scheduler", LINE = 246, MSG = "Frame.Slot 0.0\n" }
```
3. **Capture Trace Logs Offline:**
- Create an offline trace session with a specified output directory:
```bash
sudo lttng create offline_session --output=/home/trace_offline/
```
- Enable gNB trace events:
```bash
sudo lttng enable-event --userspace OAI:gNB
```
- Start capturing trace logs:
```bash
sudo lttng start
```
- Stop the trace capture:
```bash
sudo lttng stop
```
- Destroy the trace session:
```bash
sudo lttng destroy
```
- Use Babeltrace to analyze the captured trace logs:
```bash
sudo babeltrace /home/trace_offline/
```