From 179d046456886253249bbd1fbc2eab8e6516a7dc Mon Sep 17 00:00:00 2001 From: Philippe Proulx Date: Fri, 4 Sep 2015 16:12:07 -0400 Subject: [PATCH] whats-new: update for LTTng 2.7 Signed-off-by: Philippe Proulx --- contents/whats-new.md | 71 ++++++++++++++++++++++++++++++------------- toc/docs.yml | 2 +- 2 files changed, 51 insertions(+), 22 deletions(-) diff --git a/contents/whats-new.md b/contents/whats-new.md index d5a0006..8cbfd21 100644 --- a/contents/whats-new.md +++ b/contents/whats-new.md @@ -2,29 +2,58 @@ id: whats-new --- -Most of the changes of LTTng 2.6 are bug fixes, making the toolchain -more stable than ever before. Still, LTTng 2.6 adds some interesting -features to the project. - -LTTng 2.5 already supported the instrumentation and tracing of -[Java applications](#doc-java-application) through `java.util.logging` -(JUL). LTTng 2.6 goes one step further by supporting -Apache log4j 1.2. -The new log4j domain is selected using the `--log4j` option in various -commands of the `lttng` tool. - -LTTng-modules has supported system call tracing for a long time, -but until now, it was only possible to record either all of them, -or none of them. LTTng 2.6 allows the user to record specific -system call events, for example: +LTTng 2.7 ships with a generous list of new features, with essential +additions to all the project's components. + +Dynamic filtering of user space tracepoints has been available for +quite some time now +(see [Enabling and disabling events](#doc-enabling-disabling-events)). +LTTng 2.7 adds filtering support to kernel events as well. For example: + +
+lttng enable-event --kernel irq_handler_entry --filter 'irq == 28'
+
+ +LTTng 2.7 also adds wildcard support for kernel event names: 
-lttng enable-event --kernel --syscall open,fork,chdir,pipe
+lttng enable-event --kernel 'sched_*'
-Finally, the `lttng` command line tool is not only able to communicate -with humans as it used to do, but also with machines thanks to its new -[machine interface](#doc-mi) feature. +On the user space tracing side, the new [`tracelog()`](#doc-tracelog) +facility allows users to easily migrate from logging to tracing. +`tracelog()` is similar to [`tracef()`](#doc-tracef), but accepts +an additional log level parameter. + +The new `--shm-path` option of `lttng create` can be used to specify the +path where the shared memory holding the ring buffers are +created. This feature is useful when used with persistent memory file +systems to extract the latest recorded trace data in the event of a +crash requiring a reboot. The new `lttng-crash` command line +utility can extract trace data from such a file (see +[Recording trace data on persistent memory file systems](#doc-persistent-memory-file-systems)). + +LTTng-modules 2.7 and LTTng-UST 2.7 can rely on user plugins +to provide custom clock sources to their tracer. +LTTng-UST can also load a user plugin to retrieve the current CPU number. +This feature exists for very advanced use cases. See +the clock-override +and getcpu-override +examples for more details. + +Python developers can now benefit from the new +[LTTng-UST Python agent](#doc-python-application), +a Python 2/3-compatible package which allows standard Python logging +using the `logging` module to output log entries to an LTTng trace. + +Last but not least, the new `lttng track` and `lttng untrack` commands +make [PID tracking](#doc-pid-tracking) +super-fast for both the kernel and the user space domains. When one or +more PIDs are tracked, only the processes having those PIDs are allowed +to emit enabled events. + +Moreover, LTTng 2.7 boasts great stability, benifiting from piles of +bug fixes and more-than-welcome internal refactorings. -To learn more about the new features of LTTng 2.6, see -[the release announcement](//lttng.org/blog/2015/02/27/lttng-2.6-released/). +To learn more about the new features of LTTng 2.7, see +the release announcement. diff --git a/toc/docs.yml b/toc/docs.yml index c8bfa6d..39b13c7 100644 --- a/toc/docs.yml +++ b/toc/docs.yml @@ -1,7 +1,7 @@ title: The LTTng Documentation cats: - id: whats-new - title: What's new in LTTng 2.6? + title: What's new in LTTng 2.7? - id: nuts-and-bolts title: Nuts and bolts cats: -- 2.34.1