Perf (Linux)

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Performance analyzing tool in Linux

title: "Perf (Linux)" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["linux-kernel-features", "linux-programming-tools", "profilers"] description: "Performance analyzing tool in Linux" topic_path: "technology/operating-systems" source: "https://en.wikipedia.org/wiki/Perf_(Linux)" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Performance analyzing tool in Linux ::

::data[format=table title="Infobox software"]

FieldValue
nameperf
logo
screenshot
released
latest release date
latest preview date
programming languageC
operating systemLinux kernel
language count
genrePerformance monitor and testing
licenseGNU GPL
repohttps://github.com/torvalds/linux/tree/master/tools/perf
website
::

| name = perf | logo = | logo caption = | logo_size = | logo_alt = | screenshot = | caption = | screenshot_size = | screenshot_alt = | collapsible = | author = | developer = | released = | discontinued = | latest release version = | latest release date = | latest preview version = | latest preview date = | status = | programming language = C | operating system = Linux kernel | platform = | size = | language = | language count = | language footnote = | genre = Performance monitor and testing | license = GNU GPL | repo = https://github.com/torvalds/linux/tree/master/tools/perf | website =

perf (sometimes called perf_events or perf tools, originally Performance Counters for Linux, PCL) is a performance analyzing tool in Linux, available from Linux kernel version 2.6.31 in 2009. Userspace controlling utility, named perf, is accessed from the command line and provides a number of subcommands; it is capable of statistical profiling of the entire system (both kernel and userland code).

It supports hardware performance counters, tracepoints, software performance counters (e.g. hrtimer), and dynamic probes (for example, kprobes or uprobes). In 2012, two IBM engineers recognized perf (along with OProfile) as one of the two most commonly used performance counter profiling tools on Linux.

{{Anchor|RAPL}}Implementation

The interface between the perf utility and the kernel consists of only one syscall and is done via a file descriptor and a mapped memory region. Unlike LTTng or older versions of oprofile, no service daemons are needed, as most functionality is integrated into the kernel. The perf utility dumps raw data from the mapped buffer to disk when the buffer becomes filled up. According to R. Vitillo (LBNL), profiling performed by perf involves a very low overhead.

, architectures that provide support for hardware counters include x86, PowerPC64, UltraSPARC (III and IV), ARM (v5, v6, v7, Cortex-A8 and -A9), Alpha EV56 and SuperH. Usage of Last Branch Records, a branch tracing implementation available in Intel CPUs since Pentium 4, is available as a patch. Since version 3.14 of the Linux kernel mainline, released on 31 March 2014, perf also supports running average power limit (RAPL) for power consumption measurements, which is available as a feature of certain Intel CPUs.{{cite web | url = https://lwn.net/Articles/593690/ | title = Lots of new perf features | date = 2014-04-09 | access-date = 2014-04-22 | author = Jake Edge | publisher = LWN.net | url = https://lwn.net/Articles/545745/ | title = RAPL (Running Average Power Limit) driver | date = 2013-04-02 | access-date = 2014-04-22 | author = Jacob Pan | publisher = LWN.net

Perf is natively supported in many popular Linux distributions, including Red Hat Enterprise Linux (since its version 6 released in 2010) and Debian in the linux-tools-common package (since Debian 6.0 (Squeeze) released in 2011).

Subcommands

perf is used with several subcommands:

  • stat: measure total event count for single program or for system for some time
  • top: top-like dynamic view of hottest functions
  • record: measure and save sampling data for single programUrs Fässler perf file format , CERN openlab, 2011
  • report: analyze file generated by perf record; can generate flat, or graph profile.
  • annotate: annotate sources or assembly
  • sched: tracing/measuring of scheduler actions and latencies
  • list: list available events

Criticism

The documentation of perf is not very detailed (as of 2014); for example, it does not document most events or explain their aliases (often external tools are used to get names and codes of events). Perf tools also cannot profile based on true wall-clock time, something that has been addressed by the addition of off-CPU profiling.

Security

The perf subsystem of Linux kernels from 2.6.37 up to 3.8.8 and RHEL6 kernel 2.6.32 contained a security vulnerability (), which was exploited to gain root privileges by a local user. The problem was due to an incorrect type being used (32-bit int instead of 64-bit) in the event_id verification code path.

References

References

  1. Vince Weaver, [http://web.eece.maine.edu/~vweaver/projects/perf_events/ The Unofficial Linux Perf Events Web-Page]
  2. [http://web.eece.maine.edu/~vweaver/projects/perf_events/overhead/fastpath2013_perfevent_slides.pdf Linux perf event Features and Overhead] // 2013 FastPath Workshop, Vince Weaver
  3. Jake Edge, [https://lwn.net/Articles/339361/ Perfcounters added to the mainline], LWN July 1, 2009, "perfcounters being included into the mainline during the recently completed 2.6.31 merge window"
  4. A. Zanella, R. Arnold. [https://www.ibm.com/developerworks/linux/library/l-evaluatelinuxonpower/ Evaluate performance for Linux on POWER. Analyze performance using Linux tools], 12 Jun 2012 // IBM DeveloperWorks Technical library
  5. Roberto A. Vitillo ([[Lawrence Berkeley National Laboratory
  6. Arnaldo Carvalho de Melo, [https://www.linux-kongress.org/2010/slides/lk2010-perf-acme.pdf The New Linux ’perf’ tools], presentation from Linux Kongress, September, 2010
  7. (June 2009). "Intel® 64 and IA-32 Architectures Software Developer's Manual Volume 3B: System Programming Guide, Part 2". Intel.
  8. (2014-01-20). "kernel/git/torvalds/linux.git - Linux kernel source tree". Git.kernel.org.
  9. [https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Developer_Guide/perf.html 6.4. Performance Counters for Linux (PCL) Tools and perf] // RHEL Developer Guide
  10. "Debian - Details of package linux-tools-2.6.32 in squeeze". Packages.debian.org.
  11. [[Ingo Molnar]], [https://lwn.net/Articles/353295/ 'perf sched': Utility to capture, measure and analyze scheduler latencies and behavior], 17 Sep 2009
  12. [https://www.bnikolic.co.uk/blog/hpc-prof-events.html How to monitor the full range of CPU performance events] // Bojan Nikolic, 2012
  13. Robert Haas (PostgreSQL), [https://rhaas.blogspot.com/2012/06/perf-good-bad-ugly.html perf: the good, the bad, the ugly] // 6 June 2012
  14. Michael Larabel. (2013-05-15). "New Linux Kernel Vulnerability Exploited". Phoronix.
  15. corbet. (2013-05-15). "Local root vulnerability in the kernel". LWN.
  16. Joe Damato. (2013-05-20). "A closer look at a recent privilege escalation bug in Linux (CVE-2013-2094)".

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::

linux-kernel-featureslinux-programming-toolsprofilers