X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=2.10%2Flttng-docs-2.10.txt;h=375fcf5cf4d716cae7c746e04ca242b8335203be;hb=f9167c82ecaf11ed038f8dfd0a8b64c4a01ffa01;hp=10d1f443d4a38edc0d0684ed4501a9d54c9e46c6;hpb=4089946d835f19eb1338c62f6eaf76f4a91da8e6;p=lttng-docs.git diff --git a/2.10/lttng-docs-2.10.txt b/2.10/lttng-docs-2.10.txt index 10d1f44..375fcf5 100644 --- a/2.10/lttng-docs-2.10.txt +++ b/2.10/lttng-docs-2.10.txt @@ -1,12 +1,15 @@ The LTTng Documentation ======================= Philippe Proulx -v2.10, 1 August 2017 +v2.10, 25 February 2021 include::../common/copyright.txt[] +include::../common/warning-not-maintained.txt[] + + include::../common/welcome.txt[] @@ -138,7 +141,7 @@ instrumented with LTTng-UST which is explicitly allowed to block: [role="term"] ---- $ lttng create -$ lttng enable-channel --userspace --blocking-timeout=-1 blocking-channel +$ lttng enable-channel --userspace --blocking-timeout=inf blocking-channel $ lttng enable-event --userspace --channel=blocking-channel --all $ lttng start $ LTTNG_UST_ALLOW_BLOCKING=1 my-app @@ -297,6 +300,8 @@ becomes inactive or in real-time. [[installing-lttng]] == Installation +include::../common/warning-no-installation.txt[] + **LTTng** is a set of software <> which interact to <> the Linux kernel and user applications, and to <> (start and stop @@ -311,139 +316,14 @@ components are bundled into the following packages: trace user applications. Most distributions mark the LTTng-modules and LTTng-UST packages as -optional when installing LTTng-tools (which is always required). In the -following sections, we always provide the steps to install all three, -but note that: +optional when installing LTTng-tools (which is always required). Note +that: * You only need to install LTTng-modules if you intend to trace the Linux kernel. * You only need to install LTTng-UST if you intend to trace user applications. -[role="growable"] -.Availability of LTTng{nbsp}{revision} for major Linux distributions as of 25 July 2017. -|==== -|Distribution |Available in releases |Alternatives - -|https://www.ubuntu.com/[Ubuntu] -|Ubuntu{nbsp}14.04 _Trusty Tahr_ and Ubuntu{nbsp}16.04 _Xenial Xerus_: -<>. -|link:/docs/v2.9#doc-ubuntu[LTTng{nbsp}2.9 for Ubuntu{nbsp}17.04 _Zesty Zapus_]. - -<> for -other Ubuntu releases. - -|https://getfedora.org/[Fedora] -|_Not available_ -|link:/docs/v2.9#doc-fedora[LTTng{nbsp}2.9 for Fedora 26]. - -<>. - -|https://www.debian.org/[Debian] -|_Not available_ -|link:/docs/v2.9#doc-debian[LTTng{nbsp}2.9 for Debian "stretch" -(stable), Debian "buster" (testing), and Debian "sid" (unstable)]. - -<>. - -|https://www.archlinux.org/[Arch Linux] -|_Not available_ -|link:/docs/v2.9#doc-arch-linux[LTTng{nbsp}2.9 in the latest AUR packages]. - -|https://alpinelinux.org/[Alpine Linux] -|_Not available_ -|link:/docs/v2.9#doc-alpine-linux[LTTng{nbsp}2.9 for Alpine Linux "edge"]. - -<>. - -|https://www.redhat.com/[RHEL] and https://www.suse.com/[SLES] -|See http://packages.efficios.com/[EfficiOS Enterprise Packages]. -| - -|https://buildroot.org/[Buildroot] -|_Not available_ -|link:/docs/v2.9#doc-buildroot[LTTng{nbsp}2.9 for Buildroot{nbsp}2017.02 and -Buildroot{nbsp}2017.05]. - -<>. - -|http://www.openembedded.org/wiki/Main_Page[OpenEmbedded] and -https://www.yoctoproject.org/[Yocto] -|_Not available_ -|link:/docs/v2.9#doc-oe-yocto[LTTng{nbsp}2.9 for Yocto Project{nbsp}2.3 _Pyro_] -(`openembedded-core` layer). - -<>. -|==== - - -[[ubuntu]] -=== [[ubuntu-official-repositories]]Ubuntu - -[[ubuntu-ppa]] -==== noch:{LTTng} Stable {revision} PPA - -The https://launchpad.net/~lttng/+archive/ubuntu/stable-{revision}[LTTng -Stable{nbsp}{revision} PPA] offers the latest stable -LTTng{nbsp}{revision} packages for: - -* Ubuntu{nbsp}14.04 _Trusty Tahr_ -* Ubuntu{nbsp}16.04 _Xenial Xerus_ - -To install LTTng{nbsp}{revision} from the LTTng Stable{nbsp}{revision} PPA: - -. Add the LTTng Stable{nbsp}{revision} PPA repository and update the - list of packages: -+ --- -[role="term"] ----- -# apt-add-repository ppa:lttng/stable-2.10 -# apt-get update ----- --- - -. Install the main LTTng{nbsp}{revision} packages: -+ --- -[role="term"] ----- -# apt-get install lttng-tools -# apt-get install lttng-modules-dkms -# apt-get install liblttng-ust-dev ----- --- - -. **If you need to instrument and trace - <>**, install the LTTng-UST - Java agent: -+ --- -[role="term"] ----- -# apt-get install liblttng-ust-agent-java ----- --- - -. **If you need to instrument and trace - <>**, install the - LTTng-UST Python agent: -+ --- -[role="term"] ----- -# apt-get install python3-lttngust ----- --- - - -[[enterprise-distributions]] -=== RHEL, SUSE, and other enterprise distributions - -To install LTTng on enterprise Linux distributions, such as Red Hat -Enterprise Linux (RHEL) and SUSE Linux Enterprise Server (SUSE), please -see http://packages.efficios.com/[EfficiOS Enterprise Packages]. - [[building-from-source]] === Build from source @@ -626,19 +506,23 @@ tracepoints (this will generate a lot of data when tracing): . Do some operation on your system for a few seconds. For example, load a website, or list the files of a directory. -. <> and destroy the +. <> the current tracing session: + -- [role="term"] ---- -# lttng stop # lttng destroy ---- -- + The man:lttng-destroy(1) command does not destroy the trace data; it only destroys the state of the tracing session. ++ +The man:lttng-destroy(1) command also runs the man:lttng-stop(1) command +implicitly (see <>). You need to stop tracing to make LTTng flush the remaining +trace data and make the trace readable. . For the sake of this example, make the recorded trace accessible to the non-root users: @@ -871,19 +755,23 @@ $ lttng start . Go back to the running `hello` application and press Enter. The program executes all `tracepoint()` instrumentation points and exits. -. <> and destroy the +. <> the current tracing session: + -- [role="term"] ---- -$ lttng stop $ lttng destroy ---- -- + The man:lttng-destroy(1) command does not destroy the trace data; it only destroys the state of the tracing session. ++ +The man:lttng-destroy(1) command also runs the man:lttng-stop(1) command +implicitly (see <>). You need to stop tracing to make LTTng flush the remaining +trace data and make the trace readable. By default, LTTng saves the traces in +$LTTNG_HOME/lttng-traces/__name__-__date__-__time__+, @@ -1134,11 +1022,11 @@ LTTng can send the generated trace data to different locations. The _tracing session mode_ dictates where to send it. The following modes are available in LTTng{nbsp}{revision}: -Local mode:: +[[local-mode]]Local mode:: LTTng writes the traces to the file system of the machine being traced (target system). -Network streaming mode:: +[[net-streaming-mode]]Network streaming mode:: LTTng sends the traces over the network to a <> running on a remote system. @@ -1149,7 +1037,7 @@ Snapshot mode:: or to send it over the network to a <> running on a remote system. -Live mode:: +[[live-mode]]Live mode:: This mode is similar to the network streaming mode, but a live trace viewer can connect to the distant relay daemon to <> by @@ -1314,18 +1202,23 @@ discard mode, the tracer only discards the event record that doesn't fit. In discard mode, LTTng increments a count of lost event records when an -event record is lost and saves this count to the trace. In overwrite -mode, since LTTng 2.8, LTTng increments a count of lost sub-buffers when -a sub-buffer is lost and saves this count to the trace. In this mode, -the exact number of lost event records in those lost sub-buffers is not -saved to the trace. Trace analyses can use the trace's saved discarded -event record and sub-buffer counts to decide whether or not to perform -the analyses even if trace data is known to be missing. +event record is lost and saves this count to the trace. Since +LTTng{nbsp}2.8, in overwrite mode, LTTng writes to a given sub-buffer +its sequence number within its data stream. With a <>, +<>, or <> +<>, a trace reader can use such +sequence numbers to report lost packets. In overwrite mode, LTTng +doesn't write to the trace the exact number of lost event records in +those lost sub-buffers. + +Trace analyses can use saved discarded event record and sub-buffer +(packet) counts of the trace to decide whether or not to perform the +analyses even if trace data is known to be missing. There are a few ways to decrease your probability of losing event records. <> shows -how you can fine-une the sub-buffer count and size of a channel to +how you can fine-tune the sub-buffer count and size of a channel to virtually stop losing event records, though at the cost of greater memory usage. @@ -1535,7 +1428,7 @@ The LTTng project incorporates: * **LTTng-tools**: Libraries and command-line interface to control tracing sessions. ** <> (man:lttng-sessiond(8)). -** <> (man:lttng-consumerd(8)). +** <> (cmd:lttng-consumerd). ** <> (man:lttng-relayd(8)). ** <> (`liblttng-ctl`). ** <> (man:lttng(1)). @@ -1831,7 +1724,7 @@ running. You can also start the session daemon manually. .The consumer daemon. image::plumbing-consumerd.png[] -The _consumer daemon_, man:lttng-consumerd(8), is a daemon which shares +The _consumer daemon_, cmd:lttng-consumerd, is a daemon which shares ring buffers with user applications or with the LTTng kernel modules to collect trace data and send it to some location (on disk or to a <> over the network). The consumer daemon @@ -4006,7 +3899,7 @@ $ lttng enable-event --userspace 'lttng_ust_tracelog:*' [[prebuilt-ust-helpers]] === Prebuilt user space tracing helpers -The LTTng-UST package provides a few helpers in the form or preloadable +The LTTng-UST package provides a few helpers in the form of preloadable shared objects which automatically instrument system functions and calls. @@ -4168,7 +4061,7 @@ logging frameworks: .LTTng-UST Java agent imported by a Java application. image::java-app.png[] -Note that the methods described below are new in LTTng{nbsp}{revision}. +Note that the methods described below are new in LTTng{nbsp}2.8. Previous LTTng versions use another technique. NOTE: We use http://openjdk.java.net/[OpenJDK]{nbsp}8 for development @@ -5521,6 +5414,11 @@ $ lttng destroy ---- -- +The man:lttng-destroy(1) command also runs the man:lttng-stop(1) +command implicitly (see <>). You need to stop tracing to make LTTng flush the +remaining trace data and make the trace readable. + [[list-instrumentation-points]] === List the available instrumentation points @@ -5605,8 +5503,9 @@ Tracepoint or system call name. In the case of a Linux KProbe or function, this is a custom name given to the event rule. With the JUL, log4j, and Python domains, this is a logger name. -With a tracepoint, logger, or system call name, the last character -can be `*` to match anything that remains. +With a tracepoint, logger, or system call name, you can use the special +`*` globbing character to match anything (for example, `sched_*`, +`my_comp*:*msg_*`). |All. @@ -5868,6 +5767,12 @@ records>> or lost sub-buffers since the last time you ran man:lttng-start(1), warnings are printed when you run the man:lttng-stop(1) command. +IMPORTANT: You need to stop tracing to make LTTng flush the remaining +trace data and make the trace readable. Note that the +man:lttng-destroy(1) command (see +<>) also runs the man:lttng-stop(1) command implicitly. + [[enabling-disabling-channels]] === Create a channel @@ -5957,7 +5862,7 @@ in blocking mode to +__TIMEOUTUS__+: 0 (default):: Never block (non-blocking mode). --1:: +`inf`:: Block forever until space is available in a sub-buffer to record the event. @@ -6026,7 +5931,7 @@ and <>: [role="term"] ---- $ lttng create -$ lttng enable-channel --userspace --blocking-timeout=-1 blocking-channel +$ lttng enable-channel --userspace --blocking-timeout=inf blocking-channel $ lttng enable-event --userspace --channel=blocking-channel --all $ lttng start ---- @@ -6250,8 +6155,8 @@ leads to this whitelist: .PIDs 3, 7, 10, and 13 are removed from the whitelist. image::track-1-4-15-16.png[] -LTTng can track all possible PIDs again using the opt:track(1):--all -option: +LTTng can track all possible PIDs again using the +opt:lttng-track(1):--all option: [role="term"] ----