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Live mode in Trace Compass [message #1691203]

Fri, 03 April 2015 06:57

Eclipse User

I have been exploring tracecompass from couple of weeks trying to understanding the framework (guide). I have seen couple of places where it is mentioned that live tracing is supported. But i couldn't find any straightforward way to do this.

Is that support available in the latest release? If so where can we find the examples/documentation realted to the same.

Re: Live mode in Trace Compass [message #1691509 is a reply to message #1691203]

Tue, 07 April 2015 12:55

Eclipse User

Hi,

Trace compass does support live trace reading for LTTng so far. It still requires more work but can allow reading of a trace while it is being written.

Steps:
start a tracing session in the control view in live mode.
enable the desired events (kernel or user)
import the trace

It should work.

Re: Live mode in Trace Compass [message #1691516 is a reply to message #1691203]

Tue, 07 April 2015 14:10

Eclipse User

Hi Prasad

Trace Compass supports LTTng Kernel and UST live tracing to a certain extend. Trace Compass doesn't support any other types of streaming than the one provided LTTng (lttng.org).

Trace Compass supports the creation of a tracing session for live trace reading, however it has limitations. Live trace reading, means that the trace data is analyzed while tracing is ongoing. This uses also the lttng-relayd. Currently Trace Compass is able to connect to a lttng-relayd that is running at the same machine than Trace Compass. When new data is available it will populate all analyses and views (e.g. Events Table, Histogram, Control Flow view) that are open and relevant to LTTng Kernel or UST traces. Right now it is only possible to import 1 live trace at a time (Kernel or UST). The streamed trace is written to disk and Trace Compass is updated when new data arrives. It is currently not supported to read the streamed trace without storing it to disk. To create a Live session with the LTTng Tracer Control of Trace Compass refer to reference chapter "Creating a Live Tracing" of the Trace Compass User Guide: "archive.eclipse.org/tracecompass/doc/org.eclipse.tracecompass.doc.user/LTTng-Tracer-Control.html#Creating_a_Live_Tracing_Session"

For the future, we are thinking to address the current limitations. For that, we would support live streaming without reading the trace data from disk. This would lift the limitation that Trace Compass has to run on the same machine than lttng-relayd. Another enhancement would be to allow multiple traces in on session (e.g. Kernel and UST together)

Also, it would be interesting to use live trace reading to monitor remotely trace applications. For example, with dedicated analyses we could raise alarms or warnings when certain conditions are met.

Due to other priorities we don't have a timeline for these enhancements. If you're interested in contributing any enhancements to the live trace reading we would more than happy to support you with that.

Please let us know if you have any questions.

Best Regards
Bernd

Re: Live mode in Trace Compass [message #1745770 is a reply to message #1691516]

Mon, 17 October 2016 08:03

Eclipse User

I have created an example for live trace analysis on GitHub.

Sharing it here so that it might help others.

https://github.com/deviprasad-xilinx/tracecompass-livedata-example

Thanks,
Prasad

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