CPUprofileringsværktøjer

CPU profiling, sometimes referred to as CPUprofilering in certain contexts, is the process of measuring how a program uses CPU resources during execution to identify which parts of the code consume the most CPU time. The goal is to locate bottlenecks, improve performance, and understand runtime behavior.

Profiling methods fall into instrumentation-based, sampling-based, and tracing approaches. Instrumentation inserts additional code to record execution as code runs; sampling periodically collects the current call stack; tracing logs events such as function entry and exit and context switches. Each method trades accuracy, overhead, and ease of use.

Profilers often report metrics such as CPU time, wall-clock time, CPU cycles, instructions retired, cache misses, and branch mispredictions. Modern profiling frequently uses hardware performance counters (PMUs) to measure events like cache misses or IPC, and combines them with software counters to provide a fuller picture of performance.

Common tools include perf on Linux, VTune, Valgrind, gprof or gperftools, DTrace, Instruments, and various IDE profilers. Results help identify hotspots, data locality problems, and parallelization bottlenecks, guiding targeted optimizations such as algorithm changes, loop transformations, or restructuring workloads.

Limitations include profiling overhead, sampling bias, attribution challenges in multi-threaded or multi-core environments, and the fact that observed behavior may vary with workload or environment. Profiling should be complemented by repeatable benchmarks and additional analyses (memory profiling, CPU affinity, and I/O) for reliable optimization.