KCachegrind

KCachegrind is a visualization tool for profiling data generated by Valgrind's Callgrind tool. It provides interactive views of function-level costs and call graphs to identify performance bottlenecks.

Part of the KDE project, KCachegrind uses the Qt framework and reads data from Callgrind output files (cachegrind.out.*). It presents them in several views, including a flat view of per-function costs, a call graph, and a per-line view when source code is available.

Key features include inclusive and exclusive cost metrics, per-file and per-function breakdowns, color-coded heat maps, filtering and searching, and the ability to compare two data sets to highlight differences. It can annotate source code with cost data when the source is accessible.

Usage is straightforward: run a program under Valgrind with --tool=callgrind to produce a cachegrind.out file, then open it in KCachegrind. The tool supports data from other Callgrind-compatible generators as well.

KCachegrind is a widely used KDE profiling tool on Linux and other Unix-like systems, with cross-platform variants such as QCachegrind. It complements command-line performance profiling by providing visual insight into where a program spends its time and how functions call each other.