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How does a perf tool work?
The perf tool supports a list of measurable events that you can view with perf list command. The “perf_events” interface also provides a small set of common hardware events monikers. On each processor, those events get mapped onto actual events provided by the CPU if they exist, otherwise, the event cannot be used.
What does perf record do?
Sampling with perf record. The perf tool can be used to collect profiles on per-thread, per-process and per-cpu basis. That file can then be analyzed, possibly on another machine, using the perf report and perf annotate commands.
What is overhead in perf report?
The overhead can be shown in two columns as Children and Self when perf collects callchains. The self overhead is simply calculated by adding all period values of the entry – usually a function (symbol). This is the value that perf shows traditionally and sum of all the self overhead values should be 100%.
How do I cancel a perf record?
The perf tool records events until you terminate it by pressing Control and c (Ctrl+c).
What is perf report?
perf report is able to auto-detect whether a perf. data file contains branch stacks and it will automatically switch to the branch view mode, unless –no-branch-stack is used. –branch-history Add the addresses of sampled taken branches to the callstack. This allows to examine the path the program took to each sample.
How are performance measures used in the workplace?
A BARS is a newer type of performance measurement method. Essentially, it uses a scale to rate the performance of employees or groups, usually with a vertical scale that aims to eliminate the subjectivity in most performance measures.
What does perf stand for in Linux profiling?
Performance Events for Linux, called “PERF,” is the standard profiling infrastructure on Linux. You can analyze the performance of a program using the tools provided with PERF, or you can build your own tools on top of PERF.
How does perf and PMU work on a CPU?
Perf works on the Model Specific Registers of your CPU for measurements like cycles or branch-misses or so. A special Part called PMU (Performance Measurement Unit) is counting all kinds of events.
How does perf work on the model specific registers?
Perf works on the Model Specific Registers of your CPU for measurements like cycles or branch-misses or so. A special Part called PMU(Performance Measurement Unit) is counting all kinds of events.