contents/whats-new.md

   1 ---
   2 id: whats-new
   3 ---
   4
   5 LTTng 2.7 ships with a generous list of new features, with essential
   6 additions to all the project's components.
   7
   8 Dynamic filtering of user space tracepoints has been available for
   9 quite some time now
  10 (see [Enabling and disabling events](#doc-enabling-disabling-events)).
  11 LTTng 2.7 adds filtering support to kernel events as well. For example:
  12
  13 <pre class="term">
  14 lttng enable-event --kernel irq_handler_entry --filter 'irq == 28'
  15 </pre>
  16
  17 LTTng 2.7 adds wildcard support for kernel event names:
  18
  19 <pre class="term">
  20 lttng enable-event --kernel 'sched_*'
  21 </pre>
  22
  23 On the user space tracing side, the new [`tracelog()`](#doc-tracelog)
  24 facility allows users to easily migrate from logging to tracing.
  25 `tracelog()` is similar to [`tracef()`](#doc-tracef), but accepts
  26 an additional log level parameter.
  27
  28 The new `--shm-path` option of `lttng create` can be used to specify the
  29 path where the shared memory holding the ring buffers are
  30 created. This feature is useful when used with persistent memory file
  31 systems to extract the latest recorded trace data in the event of a
  32 crash requiring a reboot. The new `lttng-crash` command line
  33 utility can extract trace data from such a file (see
  34 [Recording trace data on persistent memory file systems](#doc-persistent-memory-file-systems)).
  35
  36 LTTng-UST 2.7 can rely on a user plugin to provide a custom clock source
  37 to its tracer. LTTng-UST can also load a user plugin to retrieve the
  38 current CPU number. This feature exists for very advanced use cases. See
  39 the <a href="https://github.com/lttng/lttng-ust/tree/master/doc/examples/clock-override" class="ext">clock-override</a>
  40 and <a href="https://github.com/lttng/lttng-ust/tree/master/doc/examples/getcpu-override" class="ext">getcpu-override</a>
  41 examples for more details.
  42
  43 Python developers can now benefit from the new
  44 [LTTng-UST Python agent](#doc-python-application),
  45 a Python&nbsp;2/3-compatible package which allows standard Python logging
  46 using the `logging` module to output log entries to an LTTng trace.
  47
  48 Last but not least, the new `lttng track` and `lttng untrack` commands
  49 make [<abbr title="process ID">PID</abbr> tracking](#doc-pid-tracking)
  50 super-fast for both the kernel and the user space domains. When one or
  51 more PIDs are tracked, only the processes having those PIDs are allowed
  52 to emit enabled events.
  53
  54 Moreover, LTTng 2.7 boasts great stability, benifiting from piles of
  55 bug fixes and more-than-welcome internal refactorings.
  56
  57 To learn more about the new features of LTTng 2.7, see
  58 <a href="https://lttng.org/blog/2015/10/14/lttng-2.7-released/" class="ext">the release announcement</a>.