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(References/Useful links: Added link to Chandler's talk at CppCon2015 where he uses perf a lot!)
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* [[HardwareReference]]
* [[HardwareReference]]
* [[perf_events kernel ABI]]
* [[perf_events kernel ABI]]
* [[perf tools support for Intel® Processor Trace]]
=== References/Useful links ===
* [[Useful Links]]: How perf tools work, examples of usage to solve real problems, observability articles, hardware manuals
* [ Roberto Vitillo's presentation on Perf events]
* [[Glossary]]
* [ Brendan Gregg's perf examples]
* [[Latest Manual Pages]]
* [ CppCon 2015: Chandler Carruth "Tuning C++: Benchmarks, and CPUs, and Compilers! Oh My!"]

Latest revision as of 07:45, 29 August 2022

[edit] perf: Linux profiling with performance counters

...More than just counters...

[edit] Introduction

This is the wiki page for the Linux perf command, also called perf_events. perf is powerful: it can instrument CPU performance counters, tracepoints, kprobes, and uprobes (dynamic tracing). It is capable of lightweight profiling. It is also included in the Linux kernel, under tools/perf, and is frequently updated and enhanced.

perf began as a tool for using the performance counters subsystem in Linux, and has had various enhancements to add tracing capabilities.

Performance counters are CPU hardware registers that count hardware events such as instructions executed, cache-misses suffered, or branches mispredicted. They form a basis for profiling applications to trace dynamic control flow and identify hotspots. perf provides rich generalized abstractions over hardware specific capabilities. Among others, it provides per task, per CPU and per-workload counters, sampling on top of these and source code event annotation.

Tracepoints are instrumentation points placed at logical locations in code, such as for system calls, TCP/IP events, file system operations, etc. These have negligible overhead when not in use, and can be enabled by the perf command to collect information including timestamps and stack traces. perf can also dynamically create tracepoints using the kprobes and uprobes frameworks, for kernel and userspace dynamic tracing. The possibilities with these are endless.

The userspace perf command present a simple to use interface with commands like:

To learn more, see the examples in the Tutorial.

[edit] Wiki Contents

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