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LinuxTracepoints Change Log

v1.4.1 (TBD)

  • Renamed CMake variable BUILD_TESTS to BUILD_TESTING to match CTest conventions.

v1.4.0 (2024-06-20)

  • libtracepoint-control: New perf-collect tool that records tracepoint events into a perf.data file.
  • libeventheader-decode: renamed decode-perf tool to perf-decode.
  • libtracepoint-control: TracepointSession SavePerfDataFile adds a PERF_RECORD_FINISHED_INIT record to the generated perf.data file.
  • libeventheader: tool eventheader-register deleted. Instead, use tracepoint-register from libtracepoint.
  • New field encoding event_field_encoding_binary_length16_char8. Same as event_field_encoding_string_length16_char8 except that its default format is hex_bytes.
  • New semantics for event_field_encoding_binary_length16_char8 and event_field_encoding_string_length16_char8 encodings to support nullable and variable-length fields. These encodings can now be used with any format. When used with a fixed-size format, this indicates a nullable field. For example, a field with encoding binary_length16_char8 and format signed_int with length 1, 2, 4, or 8 would be formatted as a signed integer. The same field with length 0 would be formatted as a null. Any other length would be formatted as hex_bytes.
  • Deprecated ipv4 and ipv6 formats. New code should use the ip_address format. When applied to a 4-byte field, ip_address should format as IPv4, and when applied to a 16-byte field, ip_address should format as IPv6.
  • Decoding: When converting UTF-16 field values to UTF-8 output, treat the value as UTF-16 (previously treated as UCS-2). To aid in debugging, unmatched surrogate pairs still pass-through.
  • Decoding: When processing UTF-8 fields, check for valid UTF-8 input. To aid in debugging, unmatched surrogate pairs still pass-through. Treat all other invalid UTF-8 sequences as Latin-1 sequences, i.e. if input is "valid UTF-8 A|non-UTF-8 B|valid UTF-8 C" the output will be "valid UTF-8 A|ConvertLatin1ToUtf8(B)|valid UTF-8 C".
  • Decoding: Windows decoder now generates fully-normalized IPv6 strings for IPv6 fields, matching existing behavior of the Linux decoder.
  • Decoding: If supported by the available C++ standard library, use std::to_chars instead of snprintf to convert floating-point field values to strings. This typically results in shorter strings, e.g. a float32 value might now decode to "3.14" instead of "3.1400001" because std::from_chars<float>("3.14") == std::from_chars<float>("3.1400001").
  • EventHeaderDynamic.h: Add support for generating fields with binary encoding.

v1.3.3 (2024-04-15)

  • BUG FIX: EADDRINUSE returned during TraceLoggingRegister on newer kernels. The "name already in use" detection splits on whitespace, while all other processing splits on semicolon. Fix by adding space after each semicolon in EVENTHEADER_COMMAND_TYPES.
  • libtracepoint-decode: In pipe mode, load event names at FinishedInit instead of HeaderLastFeature since not all traces emit HeaderLastFeature.
  • libtracepoint-decode: Recognize files from LP32 systems as 32-bit.
  • libtracepoint: new tool tracepoint-register for pre-registering tracepoints.
  • libeventheader: existing tool eventheader-register is deprecated in favor of tracepoint-register.
  • libeventheader-decode-dotnet: Moved to separate repository LinuxTracepoints-Net.

v1.3.2 (2024-02-27)

  • Bug fix: Open user_events_data for O_WRONLY instead of O_RDWR.

v1.3.1 (2024-01-11)

  • TracepointSession supports per-CPU buffer sizes (including 0) to allow memory usage optimization when trace producers are known to be bound to specific CPUs.
  • TracepointSession uses PERF_ATTR_SIZE_VER3 for the size of perf_event_attr to minimize the chance of incompatibilities.

v1.3.0 (2023-11-27)

  • Breaking changes to PerfDataFile:
    • dataFile.AttrCount() method replaced by EventDescCount() method.
    • dataFile.Attr(index) method replaced by EventDesc(index) method. The returned PerfEventDesc object contains an attr pointer.
    • dataFile.EventDescById(id) method replaced by FindEventDescById(id).
  • Breaking changes to PerfSampleEventInfo:
    • eventInfo.session field renamed to session_info.
    • eventInfo.attr field replaced by Attr() method.
    • eventInfo.name field replaced by Name() method.
    • eventInfo.sample_type field replaced by SampleType() method.
    • eventInfo.raw_meta field replaced by Metadata() method.
  • Breaking changes to TracepointSession:
    • session.EnableTracePoint(...) method renamed to EnableTracepoint(...).
    • session.DisableTracePoint(...) method renamed to DisableTracepoint(...).
  • EventFormatter formats timestamps as date-time if clock information is available in the event metadata. If clock information is not present, it continues to format timestamps as seconds.
  • TracepointSession provides SavePerfDataFile(filename) method to save the current contents of the session buffers into a perf.data file.
  • TracepointSession now includes ID in default sample type.
  • TracepointSession records clock information from the session.
  • TracepointSession provides access to information about the tracepoints that have been added to the session (metadata, status, statistics).
  • PerfDataFile decodes clock information from perf.data files if present.
  • PerfDataFile provides access to more metadata via PerfEventDesc struct.
  • PerfDataFile provides EventDataSize for determining the size of an event.
  • New PerfDataFileWriter class for generating perf.data files.
  • Changed procedure for locating the user_events_data file.
    • Old: parse /proc/mounts to determine the tracefs or debugfs mount point, then use that as the root for the user_events_data path.
    • New: try /sys/kernel/tracing/user_events_data; if that doesn't exist, parse /proc/mounts to find the tracefs or debugfs mount point.
    • Rationale: Probe an absolute path so that containers don't have to create a fake /proc/mounts and for efficiency in the common case.

v1.2.1 (2023-07-24)

  • Prefer user_events_data from tracefs over user_events_data from debugfs.

v1.2 (2023-06-27)

  • Added "Preregister" methods to the TracepointCache class so that a controller can pre-register events that it wants to collect.
  • If no consumers have enabled a tracepoint, the kernel now returns EBADF. The provider APIs have been updated to be consistent with the new behavior.

v1.1 (2023-06-20)

  • Add namespaces to the C++ APIs.
  • Move non-eventheader logic from eventheader-decode to new tracepoint-decode library.
  • Add new libtracepoint-control library.