• Add auxiliary event automatically if needed by the (Intel-) hardware.

• Removed deprecated warnings about the sampling interface (and the old sampling interface).
• New feature: Access interim results from counters without stopping the counter using live counters.
• New feature: Sampling the user stack (see the documentation).
• New feature: Create custom metrics using expressions, e.g., "instructions/cycles" (see the documentation).
• New feature: Use metric when sampling counter values.
• New feature: Control scheduling of events to physical hardware counters (see the documentation).
• New feature: Added time events (e.g., seconds, milliseconds, etc.) as virtual counters (see the documentation).

• Fixed multiple compatibility issues where the code relied on Linux kernel features that might not available on different versions.

• Fixed compatibility for older Linux versions that don't provide PERF_MEM_BLK, PERF_MEM_LVLNUM, and PERF_MEM_REMOTE.

• Fixed error using decltype instead of typeof (by @toge)

• Restructured the build-system – thanks to @foolnotion:
  • Examples are no longer included into default build and must be activated with -DBUILD_EXAMPLES=1 (see documentation).
  • New feature: Added option to install the library using -DCMAKE_INSTALL_PREFIX=/path/to/libperf-cpp (see documentation).
• New feature: Define period or frequency along with trigger events when sampling (see documentation).
• New feature: cgroup sampling (see documentation).
• New feature: Sampling for context switches (see documentation).
• New feature: Sampling for throttle events (see documentation).
• New feature: Sampling for raw values (see documentation).
• New feature: Sampling for transaction aborts (see documentation).
• New feature: Print results from perf::EventCounter as a table using perf::CounterResult::to_string().
• Automatically discover AMD Instruction Based Sampling (IBS) PMUs when running on AMD hardware (see documentation).
• Automatically discover Intel Processor Event Based Sampling (PEBS) memory events when running on Intel hardware (see documentation).
• Enable Intel PEBS by default (used interrupt-based sampling so far, if not specified otherwise in perf::SampleConfig::precise_ip()).
• Support Linux Kernel down to 4.0 – Kernels no longer need to be specified via compiler defines.
• Close sampler automatically (i.e., free all buffers and close counters) when destructing.

• Fixed compilation error on ARM machines (__builtin_cpu_is() is not supported) – thanks to @Tratori.

This release comes with many new features, especially focusing on the interface for sampling and error handling using exceptions. Please note that we will maintain backward compatibility for the "old"-styled interface until v0.8.0. Deprecated interfaces are marked as such using [[deprecated()]] annotations and may yield warnings during compilation.

Changelog:

• Samples can now be asked if they contain losses (and if so, how many). Sample records can be lost, e.g., if the buffer is out of capacity or the CPU is too busy.
• Errors when adding performance counters and opening/starting samplers are now communicated via exceptions instead of an error variable.
• Introduced a new interface for specifying the data that should be recorded for triggers through Sampler::values().
• Introduced a new interface for specifying the triggers for sampling through Sampler::trigger().
• Added the option to use multiple triggers for sampling (including example).
• Added the option to use different precisions for each trigger.
• Added the option to open() the sampler separately. If the sampler is not opened separately, start() will open the sampler.
• Added option to ask samples if they are precise (depends on the precision level for triggers).

• Using Counter-Names from perf::CounterDefinition (via std::string_view) instead of copying strings for more performance.
• Switched from PERF_MEM_LVL_* to newer PERF_MEM_LVLNUM namespace as PERF_MEM_LVL_* is marked as deprecated in linux/perf_event.h.
• Added multithread and multicore recording.
• Added multithread and multicore sampling.

• Switched to LGPL (instead of AGPL).
• Added more complex WeightStruct sampling (via PERF_SAMPLE_WEIGHT_STRUCT) to enable sampling for instruction latencies on newer hardware (e.g., Intel's Sapphire Rapids).
• Implemented debug output for counters by setting an is_debug flag in the config.
• Added more complex branch sampling.
• Implemented auto-correct of precise_ip configuration if the hardware rejects the initial user-set config.
• Implemented auxiliary counter to enable memory sampling on Intel's Sapphire Rapids.

• Disabled counter cgroup-switches for Linux Kernel < 5.13 (was first introduced with that version).
• Disabled sampling for Data Page Size and Code Page Size for Linux Kernel < 5.11 (was first introduced with that version).

• Added support for register sampling.
• Added make perf-list to automatically extract perf counters from the underlying hardware.
• Added support for sampling data and code page sizes.

• Added support for event sampling.
• Added full documentation.

• Fixed std::move on perf::CounterDefintion.

• Added metrics (e.g., CPI).
• Added json/csv conversion from results.
• Added examples.