Kernel Recipes 2013 - Viewing real time ltt trace using gtkwave

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This presentation will explain how to use some ltt to be viewd in gtkwave, a graphical visualization tool, developped by the Parrot team. It will also explain why this tool was developed, review some of the problems that have been analyzed using these traces. It will finally end up on the ongoing integration with LTTng 2.x.

Technologie

Viewing LTTng traces with GTKWave
ivan.djelic@parrot.com
Sept 2013
LTTng+GTKWave

What is LTT ?
▶ Linux Trace Toolkit, appeared circa 1999 (http://www.opersys.com)
▶ Kernel patch + kernel module + userland daemon + tools
▶ Collects kernel event-data: interrupts, context switches, page faults,
syscalls, etc
▶ Userspace events also supported
▶ Traces can be post-processed and viewed with LTTV
▶ LTT now superseded by LTTng (http://lttng.org)
LTTng+GTKWave LTTng

LTTng 2.x
▶ Released in 2011
▶ Advanced low-overhead architecture
▶ Kernel patch no longer needed !
▶ Uses new trace format (CTF, Common Trace Format)
▶ LTTV support WIP
▶ Eclipse plugin:
http://www.eclipse.org/linuxtools/projectPages/lttng
▶ LTTng 2.x/0.x events are different: no compatibility with old LTTng
tools
LTTng+GTKWave LTTng

Eclipse LTTng perspective
LTTng+GTKWave LTTng

What is GTKWave ?
▶ GTK+ based waveform viewer
▶ Supports several le formats: FST, Verilog VCD, GHW, etc
▶ Handles large trace les and many trace signals at once
▶ Provides C library for creating traces in its native LXT le
format
LTTng+GTKWave GTKWave

LTTng+GTKWave
▶ A tool called ltt2lxt parses an LTT trace and generates two
les:
▶ a .lxt le (an LXT trace)
▶ a .sav le (a layout of the signals)
▶ Supports LTTng-0.x (legacy) traces, support for LTTng-2.x
trace is alpha
▶ Kernel symbols optionally used to convert addresses into
function():line strings
▶ Makes use of GTKWave nice zooming features
▶ Does not replace but complements LTTV and other tools
LTTng+GTKWave Viewing LTTng traces in GTKWave

Conversion tools: ltt2lxt and lttng2lxt
LTTng+GTKWave Viewing LTTng traces in GTKWave

An LTTng trace in GTKwave
LTTng+GTKWave Viewing LTTng traces in GTKWave

To contribute...
▶ https://github.com/idjelic/lttng2lxt
LTTng+GTKWave Viewing LTTng traces in GTKWave

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