computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and softw ...

, SystemTap () is a

scripting language In computing, a script is a relatively short and simple set of instructions that typically automation, automate an otherwise manual process. The act of writing a script is called scripting. A scripting language or script language is a programming ...

and

tool A tool is an Physical object, object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many Tool use by animals, animals use simple tools, only human bei ...

for dynamically instrumenting running production

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

-based

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

s. System administrators can use SystemTap to extract, filter and summarize data in order to enable diagnosis of complex performance or functional problems. SystemTap consists of

free and open-source software Free and open-source software (FOSS) is software available under a license that grants users the right to use, modify, and distribute the software modified or not to everyone free of charge. FOSS is an inclusive umbrella term encompassing free ...

and includes contributions from

Red Hat Red Hat, Inc. (formerly Red Hat Software, Inc.) is an American software company that provides open source software products to enterprises and is a subsidiary of IBM. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North ...

IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...

Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, and Delaware General Corporation Law, incorporated in Delaware. Intel designs, manufactures, and sells computer compo ...

Hitachi () is a Japanese Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1910 and headquartered in Chiyoda, Tokyo. The company is active in various industries, including digital systems, power and renewable ener ...

Oracle An oracle is a person or thing considered to provide insight, wise counsel or prophetic predictions, most notably including precognition of the future, inspired by deities. If done through occultic means, it is a form of divination. Descript ...

, the University of Wisconsin-Madison and other community members.

History

SystemTap debuted in 2005 in

Red Hat Enterprise Linux Red Hat Enterprise Linux (RHEL) is a commercial Linux distribution developed by Red Hat. Red Hat Enterprise Linux is released in server versions for x86-64, Power ISA, ARM64, and IBM Z and a desktop version for x86-64. Fedora Linux and ...

4 Update 2 as a technology preview. After four years in development, SystemTap 1.0 was released in 2009. , SystemTap runs fully supported in all Linux distributions including RHEL / CentOS 5 since update 2, SLES 10, Fedora, Debian and Ubuntu. Tracepoints in the

CPython CPython is the reference implementation of the Python programming language. Written in C and Python, CPython is the default and most widely used implementation of the Python language. CPython can be defined as both an interpreter and a comp ...

VM and

JVM A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally descri ...

were added in SystemTap 1.2 in 2009. In November 2019, SystemTap 4.2 included

prometheus In Greek mythology, Prometheus (; , , possibly meaning "forethought")Smith"Prometheus". is a Titans, Titan. He is best known for defying the Olympian gods by taking theft of fire, fire from them and giving it to humanity in the form of technol ...

exporter.

Usage

SystemTap files are written in the SystemTap language (saved as .stp files) and run with the stap command-line. The system carries out a number of analysis passes on the script before allowing it to run. Scripts may be executed with one of three backends selected by the --runtime= option. The default is a loadable kernel module, which has the fullest capability to inspect and manipulate any part of the system, and therefore requires most privilege. Another backend is based on the

dynamic program analysis Dynamics (from Greek δυναμικός ''dynamikos'' "powerful", from δύναμις ''dynamis'' " power") or dynamic may refer to: Physics and engineering * Dynamics (mechanics), the study of forces and their effect on motion Brands and en ...

library DynInst to instrument the user's own user-space programs only, and requires least privilege. The newest backend is based on eBPF byte-code, is limited to the

kernel interpreter's capabilities, and requires an intermediate level of privilege. In each case, the module is unloaded when the script has finished running. Scripts generally focus on events (such as starting or finishing a script), compiled-in probe points such as Linux "tracepoints", or the execution of functions or statements in the kernel or user-space. Some "guru mode" scripts may also have embedded C, which may run with the -g command-line option. However, use of guru mode is discouraged, and each SystemTap release includes more probe points designed to remove the need for guru-mode scripts. Guru mode is required in order to permit scripts to ''modify'' state in the instrumented software, such as to apply some types of emergency security fixes. As of SystemTap version 1.7, the software implements the new ''stapsys'' group and privilege level.

Simple examples

The following script shows all applications setting TCP socket options on the system, what options are being set, and whether the option is set successfully or not. # Show sockets setting options # Return enabled or disabled based on value of optval function getstatus(optval) probe begin # Set a socket option probe tcp.setsockopt # Check setting the socket option worked probe tcp.setsockopt.return probe end Many other examples are shipped with SystemTap. There are also real-world examples of SystemTap use at the War Stories page.

Importing scripts from other tracing technologies

SystemTap can attach to

DTrace DTrace is a comprehensive dynamic tracing framework originally created by Sun Microsystems for troubleshooting kernel and application problems on production systems in real time. Originally developed for Solaris, it has since been released un ...

markers when they are compiled into an application using macros from the sys/sdt.h header file.

History

Usage

Simple examples

Importing scripts from other tracing technologies

See also

References

External links