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View power on time linux6/7/2023 ![]() Perf stat -d command # CPU counter statistics for the specified PID, until Ctrl-C: Perf stat command # Detailed CPU counter statistics (includes extras) for the specified command: Listing Events # Listing all currently known events:Ĭounting Events # CPU counter statistics for the specified command: trace: collect details from every event.sample: collect details (eg, instruction pointer or stack) from a subset of events (once every.statistics/ count: increment an integer counter on events.Terminology I'm using, from lowest to highest overhead: Some useful one-liners I've gathered or written. Note that I use the "#" prompt to signify that these commands were run as root, and I'll use "$" for user commands. These were issued by the kernel function blk_peek_request(), and walking down the stacks, about half of these 32% were from the close() system call. The perf report output shows that 2,216 events were traced (disk I/O), 32% of which from a dd command. ![]() A summary of the perf.data file was printed using perf report, which builds a tree from the stack traces, coalescing common paths, and showing percentages for each path. Trace data is written to a perf.data file, and tracing ended when Ctrl-C was hit. Options included -a to trace all CPUs, and -g to capture call graphs (stack traces). ģ2.13% dd blk_peek_requestĪ perf record command was used to trace the block:block_rq_issue probe, which fires when a block device I/O request is issued (disk I/O). # Samples: 2K of event 'block:block_rq_issue' # perf record -e block:block_rq_issue -ag Starting with a screenshot, here's perf version 3.9.3 tracing disk I/O: This page is under construction, and there's a lot more to perf_events that I'd like to add. The next sections introduce perf_events further, starting with a screenshot, one-liners, and then background. Key sections to start with are: Events, One-Liners, Presentations, Prerequisites, CPU statistics, Timed Profiling, and Flame Graphs.Īlso see my Posts about perf_events, and Links for the main (official) perf_events page, awesome tutorial, and other links. This page includes my examples of perf_events. My perf-tools collection (github) uses both perf_events and ftrace as needed. ![]() While it uses many Linux tracing features, some are not yet exposed via the perf command, and need to be used via the ftrace interface instead. Perf_events is part of the Linux kernel, under tools/perf. What reasons are threads leaving the CPU?.Is a certain kernel function being called, and how often?.Which code-paths are allocating memory, and how much?.Which code-paths are causing CPU level 2 cache misses?.Why is the kernel on-CPU so much? What code-paths?.Perf_events is an event-oriented observability tool, which can help you solve advanced performance and troubleshooting functions. This is not an official perf page, for either perf_events or the T-shirt. Searching for just "perf" finds sites on the police, petroleum, weed control, and a T-shirt. Like Vince Weaver, I'll call it perf_events so that you can search on that term later. These are some examples of using the perf Linux profiler, which has also been called Performance Counters for Linux (PCL), Linux perf events (LPE), or perf_events. Image license: creative commons Attribution-ShareAlike 4.0. Systems Performance: Enterprise and the Cloud, 2nd Edition How To Add eBPF Observability To Your ProductīPF binaries: BTF, CO-RE, and the future of BPF perf tools USENIX LISA2021 Computing Performance: On the Horizon USENIX SREcon APAC 2022: Computing Performance: What's on the Horizon EBPF Observability Tools Are Not Security Tools
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