Since we released the first public version of LTTng Scope, our new experimental graphical trace viewer, I thought it would be nice to do a quick tutorial on how to get started using it.
We'll go trough collecting a Linux kernel trace with LTTng, opening it in LTTng Scope, and then use a simple filter to pinpoint some events.
A few months ago on the lttng-dev mailing list, Milian Wolff reported that his test application was seeing noticeable startup delays because it was linked against liblttng-ust. He didn't start a tracing session and his test program didn't call any code in liblttng-ust. In fact, the test program contained fewer lines of code than a standard Hello, World! application:
int main()
{
return 0;
}
If you've ever suffered from lost trace event records when using LTTng-UST then you might be interested to know that LTTng 2.10 includes a new feature to prevent that from happening: blocking mode support for channels.
This long-awaited feature makes it possible for LTTng-UST to wait until space becomes available in the trace buffers instead of losing existing event records when new ones arrive.
In my day to day job at EfficiOS, I often have to manually test different versions and configurations of LTTng. The typical way to test LTTng 2.7 if LTTng 2.8 is installed, for example, is, for each of the three LTTng projects (LTTng-tools, LTTng-UST, and LTTng-modules):
This whole manual process becomes painful over time. I'm not even mentioning the situations where I also need to test different versions of the tools' dependencies, like Glib and Libxml2. The same laborious process applies to Babeltrace.
In an ideal world, I would have multiple environments containing
different versions and configurations of the tools and dependencies
which form the LTTng ecosystem. This is totally possible with the
various environment variables and configure flags (--prefix,
--with-lttng-ust-prefix, and the rest) of the projects. And this is
exactly what vlttng exploits to
achieve this. vlttng is a project I've been working on in my spare time.
In this article I explain what vlttng is exactly, after which I show a concrete example.
Hi everyone! Alexandre here.
In this blog post, I will demonstrate how to generate LTTng traces from the Trace Compass viewer using the LTTng-UST Java agent integration. This should effectively explain:
java.util.logging
tracepoints.This is basically an update of Tutorial: Tracing Java Logging Frameworks for LTTng 2.7 and above. I will also go into more details regarding how to use configuration files and how to record Trace Compass traces.