[ltt-dev] LTTng 0.16 for 2.6.27-rc2 (ftrace integration)

Mathieu Desnoyers mathieu.desnoyers at polymtl.ca
Tue Aug 12 11:04:01 EDT 2008


I just released the latest LTTng version I used to pinpoint the "prove
locking correctness" latency issue. It integrates with ftrace (only the
dynamic function tracing part) with what I call a "tap".

See http://lkml.org/lkml/2008/8/5/321 to find out how I dug in this

Basically, a "tap" is a set of "enable/disable" probes one can connect
on specific markers/tracepoints. These probes enable/disable a "tap",
which controls recording of specific events to the trace.

Since dynamic function tracing is very high overhead, this tap mechanism
can be used to control the event flow to only trace the interesting code
areas. All markers named "tap_*" are also controlled by such mechanism.
By removing a comment from the ltt-armall script, one can use the tap to
enable lockdep event tracing.

See the new ltt-armtap and the modified ltt-armall scripts in the
ltt-control package for details.

New versions :

LTTng gitweb

LTTng Git tree
git://git.kernel.org/pub/scm/linux/kernel/git/compudj/linux-2.6-lttng.git 2.6.27-rc2-lttng

LTTng tarball



Testing, especially of the new tap scripts, is welcome.


Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

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