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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /tools/perf/Documentation/perf.data-file-format.txt | |
parent | Initial commit. (diff) | |
download | linux-upstream.tar.xz linux-upstream.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tools/perf/Documentation/perf.data-file-format.txt')
-rw-r--r-- | tools/perf/Documentation/perf.data-file-format.txt | 637 |
1 files changed, 637 insertions, 0 deletions
diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt new file mode 100644 index 000000000..9ee966407 --- /dev/null +++ b/tools/perf/Documentation/perf.data-file-format.txt @@ -0,0 +1,637 @@ +perf.data format + +Uptodate as of v4.7 + +This document describes the on-disk perf.data format, generated by perf record +or perf inject and consumed by the other perf tools. + +On a high level perf.data contains the events generated by the PMUs, plus metadata. + +All fields are in native-endian of the machine that generated the perf.data. + +When perf is writing to a pipe it uses a special version of the file +format that does not rely on seeking to adjust data offsets. This +format is described in "Pipe-mode data" section. The pipe data version can be +augmented with additional events using perf inject. + +The file starts with a perf_header: + +struct perf_header { + char magic[8]; /* PERFILE2 */ + uint64_t size; /* size of the header */ + uint64_t attr_size; /* size of an attribute in attrs */ + struct perf_file_section attrs; + struct perf_file_section data; + struct perf_file_section event_types; + uint64_t flags; + uint64_t flags1[3]; +}; + +The magic number identifies the perf file and the version. Current perf versions +use PERFILE2. Old perf versions generated a version 1 format (PERFFILE). Version 1 +is not described here. The magic number also identifies the endian. When the +magic value is 64bit byte swapped compared the file is in non-native +endian. + +A perf_file_section contains a pointer to another section of the perf file. +The header contains three such pointers: for attributes, data and event types. + +struct perf_file_section { + uint64_t offset; /* offset from start of file */ + uint64_t size; /* size of the section */ +}; + +Flags section: + +For each of the optional features a perf_file_section it placed after the data +section if the feature bit is set in the perf_header flags bitset. The +respective perf_file_section points to the data of the additional header and +defines its size. + +Some headers consist of strings, which are defined like this: + +struct perf_header_string { + uint32_t len; + char string[len]; /* zero terminated */ +}; + +Some headers consist of a sequence of strings, which start with a + +struct perf_header_string_list { + uint32_t nr; + struct perf_header_string strings[nr]; /* variable length records */ +}; + +The bits are the flags bits in a 256 bit bitmap starting with +flags. These define the valid bits: + + HEADER_RESERVED = 0, /* always cleared */ + HEADER_FIRST_FEATURE = 1, + HEADER_TRACING_DATA = 1, + +Describe me. + + HEADER_BUILD_ID = 2, + +The header consists of an sequence of build_id_event. The size of each record +is defined by header.size (see perf_event.h). Each event defines a ELF build id +for a executable file name for a pid. An ELF build id is a unique identifier +assigned by the linker to an executable. + +struct build_id_event { + struct perf_event_header header; + pid_t pid; + uint8_t build_id[24]; + char filename[header.size - offsetof(struct build_id_event, filename)]; +}; + + HEADER_HOSTNAME = 3, + +A perf_header_string with the hostname where the data was collected +(uname -n) + + HEADER_OSRELEASE = 4, + +A perf_header_string with the os release where the data was collected +(uname -r) + + HEADER_VERSION = 5, + +A perf_header_string with the perf user tool version where the +data was collected. This is the same as the version of the source tree +the perf tool was built from. + + HEADER_ARCH = 6, + +A perf_header_string with the CPU architecture (uname -m) + + HEADER_NRCPUS = 7, + +A structure defining the number of CPUs. + +struct nr_cpus { + uint32_t nr_cpus_available; /* CPUs not yet onlined */ + uint32_t nr_cpus_online; +}; + + HEADER_CPUDESC = 8, + +A perf_header_string with description of the CPU. On x86 this is the model name +in /proc/cpuinfo + + HEADER_CPUID = 9, + +A perf_header_string with the exact CPU type. On x86 this is +vendor,family,model,stepping. For example: GenuineIntel,6,69,1 + + HEADER_TOTAL_MEM = 10, + +An uint64_t with the total memory in kilobytes. + + HEADER_CMDLINE = 11, + +A perf_header_string_list with the perf arg-vector used to collect the data. + + HEADER_EVENT_DESC = 12, + +Another description of the perf_event_attrs, more detailed than header.attrs +including IDs and names. See perf_event.h or the man page for a description +of a struct perf_event_attr. + +struct { + uint32_t nr; /* number of events */ + uint32_t attr_size; /* size of each perf_event_attr */ + struct { + struct perf_event_attr attr; /* size of attr_size */ + uint32_t nr_ids; + struct perf_header_string event_string; + uint64_t ids[nr_ids]; + } events[nr]; /* Variable length records */ +}; + + HEADER_CPU_TOPOLOGY = 13, + +struct { + /* + * First revision of HEADER_CPU_TOPOLOGY + * + * See 'struct perf_header_string_list' definition earlier + * in this file. + */ + + struct perf_header_string_list cores; /* Variable length */ + struct perf_header_string_list threads; /* Variable length */ + + /* + * Second revision of HEADER_CPU_TOPOLOGY, older tools + * will not consider what comes next + */ + + struct { + uint32_t core_id; + uint32_t socket_id; + } cpus[nr]; /* Variable length records */ + /* 'nr' comes from previously processed HEADER_NRCPUS's nr_cpu_avail */ + + /* + * Third revision of HEADER_CPU_TOPOLOGY, older tools + * will not consider what comes next + */ + + struct perf_header_string_list dies; /* Variable length */ + uint32_t die_id[nr_cpus_avail]; /* from previously processed HEADER_NR_CPUS, VLA */ +}; + +Example: + sibling sockets : 0-8 + sibling dies : 0-3 + sibling dies : 4-7 + sibling threads : 0-1 + sibling threads : 2-3 + sibling threads : 4-5 + sibling threads : 6-7 + + HEADER_NUMA_TOPOLOGY = 14, + + A list of NUMA node descriptions + +struct { + uint32_t nr; + struct { + uint32_t nodenr; + uint64_t mem_total; + uint64_t mem_free; + struct perf_header_string cpus; + } nodes[nr]; /* Variable length records */ +}; + + HEADER_BRANCH_STACK = 15, + +Not implemented in perf. + + HEADER_PMU_MAPPINGS = 16, + + A list of PMU structures, defining the different PMUs supported by perf. + +struct { + uint32_t nr; + struct pmu { + uint32_t pmu_type; + struct perf_header_string pmu_name; + } [nr]; /* Variable length records */ +}; + + HEADER_GROUP_DESC = 17, + + Description of counter groups ({...} in perf syntax) + +struct { + uint32_t nr; + struct { + struct perf_header_string string; + uint32_t leader_idx; + uint32_t nr_members; + } [nr]; /* Variable length records */ +}; + + HEADER_AUXTRACE = 18, + +Define additional auxtrace areas in the perf.data. auxtrace is used to store +undecoded hardware tracing information, such as Intel Processor Trace data. + +/** + * struct auxtrace_index_entry - indexes a AUX area tracing event within a + * perf.data file. + * @file_offset: offset within the perf.data file + * @sz: size of the event + */ +struct auxtrace_index_entry { + u64 file_offset; + u64 sz; +}; + +#define PERF_AUXTRACE_INDEX_ENTRY_COUNT 256 + +/** + * struct auxtrace_index - index of AUX area tracing events within a perf.data + * file. + * @list: linking a number of arrays of entries + * @nr: number of entries + * @entries: array of entries + */ +struct auxtrace_index { + struct list_head list; + size_t nr; + struct auxtrace_index_entry entries[PERF_AUXTRACE_INDEX_ENTRY_COUNT]; +}; + + HEADER_STAT = 19, + +This is merely a flag signifying that the data section contains data +recorded from perf stat record. + + HEADER_CACHE = 20, + +Description of the cache hierarchy. Based on the Linux sysfs format +in /sys/devices/system/cpu/cpu*/cache/ + + u32 version Currently always 1 + u32 number_of_cache_levels + +struct { + u32 level; + u32 line_size; + u32 sets; + u32 ways; + struct perf_header_string type; + struct perf_header_string size; + struct perf_header_string map; +}[number_of_cache_levels]; + + HEADER_SAMPLE_TIME = 21, + +Two uint64_t for the time of first sample and the time of last sample. + + HEADER_SAMPLE_TOPOLOGY = 22, + +Physical memory map and its node assignments. + +The format of data in MEM_TOPOLOGY is as follows: + + u64 version; // Currently 1 + u64 block_size_bytes; // /sys/devices/system/memory/block_size_bytes + u64 count; // number of nodes + +struct memory_node { + u64 node_id; // node index + u64 size; // size of bitmap + struct bitmap { + /* size of bitmap again */ + u64 bitmapsize; + /* bitmap of memory indexes that belongs to node */ + /* /sys/devices/system/node/node<NODE>/memory<INDEX> */ + u64 entries[(bitmapsize/64)+1]; + } +}[count]; + +The MEM_TOPOLOGY can be displayed with following command: + +$ perf report --header-only -I +... +# memory nodes (nr 1, block size 0x8000000): +# 0 [7G]: 0-23,32-69 + + HEADER_CLOCKID = 23, + +One uint64_t for the clockid frequency, specified, for instance, via 'perf +record -k' (see clock_gettime()), to enable timestamps derived metrics +conversion into wall clock time on the reporting stage. + + HEADER_DIR_FORMAT = 24, + +The data files layout is described by HEADER_DIR_FORMAT feature. Currently it +holds only version number (1): + + uint64_t version; + +The current version holds only version value (1) means that data files: + +- Follow the 'data.*' name format. + +- Contain raw events data in standard perf format as read from kernel (and need + to be sorted) + +Future versions are expected to describe different data files layout according +to special needs. + + HEADER_BPF_PROG_INFO = 25, + +struct bpf_prog_info_linear, which contains detailed information about +a BPF program, including type, id, tag, jited/xlated instructions, etc. + + HEADER_BPF_BTF = 26, + +Contains BPF Type Format (BTF). For more information about BTF, please +refer to Documentation/bpf/btf.rst. + +struct { + u32 id; + u32 data_size; + char data[]; +}; + + HEADER_COMPRESSED = 27, + +struct { + u32 version; + u32 type; + u32 level; + u32 ratio; + u32 mmap_len; +}; + +Indicates that trace contains records of PERF_RECORD_COMPRESSED type +that have perf_events records in compressed form. + + HEADER_CPU_PMU_CAPS = 28, + + A list of cpu PMU capabilities. The format of data is as below. + +struct { + u32 nr_cpu_pmu_caps; + { + char name[]; + char value[]; + } [nr_cpu_pmu_caps] +}; + + +Example: + cpu pmu capabilities: branches=32, max_precise=3, pmu_name=icelake + + HEADER_CLOCK_DATA = 29, + + Contains clock id and its reference time together with wall clock + time taken at the 'same time', both values are in nanoseconds. + The format of data is as below. + +struct { + u32 version; /* version = 1 */ + u32 clockid; + u64 wall_clock_ns; + u64 clockid_time_ns; +}; + + other bits are reserved and should ignored for now + HEADER_FEAT_BITS = 256, + +Attributes + +This is an array of perf_event_attrs, each attr_size bytes long, which defines +each event collected. See perf_event.h or the man page for a detailed +description. + +Data + +This section is the bulk of the file. It consist of a stream of perf_events +describing events. This matches the format generated by the kernel. +See perf_event.h or the manpage for a detailed description. + +Some notes on parsing: + +Ordering + +The events are not necessarily in time stamp order, as they can be +collected in parallel on different CPUs. If the events should be +processed in time order they need to be sorted first. It is possible +to only do a partial sort using the FINISHED_ROUND event header (see +below). perf record guarantees that there is no reordering over a +FINISHED_ROUND. + +ID vs IDENTIFIER + +When the event stream contains multiple events each event is identified +by an ID. This can be either through the PERF_SAMPLE_ID or the +PERF_SAMPLE_IDENTIFIER header. The PERF_SAMPLE_IDENTIFIER header is +at a fixed offset from the event header, which allows reliable +parsing of the header. Relying on ID may be ambiguous. +IDENTIFIER is only supported by newer Linux kernels. + +Perf record specific events: + +In addition to the kernel generated event types perf record adds its +own event types (in addition it also synthesizes some kernel events, +for example MMAP events) + + PERF_RECORD_USER_TYPE_START = 64, + PERF_RECORD_HEADER_ATTR = 64, + +struct attr_event { + struct perf_event_header header; + struct perf_event_attr attr; + uint64_t id[]; +}; + + PERF_RECORD_HEADER_EVENT_TYPE = 65, /* deprecated */ + +#define MAX_EVENT_NAME 64 + +struct perf_trace_event_type { + uint64_t event_id; + char name[MAX_EVENT_NAME]; +}; + +struct event_type_event { + struct perf_event_header header; + struct perf_trace_event_type event_type; +}; + + + PERF_RECORD_HEADER_TRACING_DATA = 66, + +Describe me + +struct tracing_data_event { + struct perf_event_header header; + uint32_t size; +}; + + PERF_RECORD_HEADER_BUILD_ID = 67, + +Define a ELF build ID for a referenced executable. + + struct build_id_event; /* See above */ + + PERF_RECORD_FINISHED_ROUND = 68, + +No event reordering over this header. No payload. + + PERF_RECORD_ID_INDEX = 69, + +Map event ids to CPUs and TIDs. + +struct id_index_entry { + uint64_t id; + uint64_t idx; + uint64_t cpu; + uint64_t tid; +}; + +struct id_index_event { + struct perf_event_header header; + uint64_t nr; + struct id_index_entry entries[nr]; +}; + + PERF_RECORD_AUXTRACE_INFO = 70, + +Auxtrace type specific information. Describe me + +struct auxtrace_info_event { + struct perf_event_header header; + uint32_t type; + uint32_t reserved__; /* For alignment */ + uint64_t priv[]; +}; + + PERF_RECORD_AUXTRACE = 71, + +Defines auxtrace data. Followed by the actual data. The contents of +the auxtrace data is dependent on the event and the CPU. For example +for Intel Processor Trace it contains Processor Trace data generated +by the CPU. + +struct auxtrace_event { + struct perf_event_header header; + uint64_t size; + uint64_t offset; + uint64_t reference; + uint32_t idx; + uint32_t tid; + uint32_t cpu; + uint32_t reserved__; /* For alignment */ +}; + +struct aux_event { + struct perf_event_header header; + uint64_t aux_offset; + uint64_t aux_size; + uint64_t flags; +}; + + PERF_RECORD_AUXTRACE_ERROR = 72, + +Describes an error in hardware tracing + +enum auxtrace_error_type { + PERF_AUXTRACE_ERROR_ITRACE = 1, + PERF_AUXTRACE_ERROR_MAX +}; + +#define MAX_AUXTRACE_ERROR_MSG 64 + +struct auxtrace_error_event { + struct perf_event_header header; + uint32_t type; + uint32_t code; + uint32_t cpu; + uint32_t pid; + uint32_t tid; + uint32_t reserved__; /* For alignment */ + uint64_t ip; + char msg[MAX_AUXTRACE_ERROR_MSG]; +}; + + PERF_RECORD_HEADER_FEATURE = 80, + +Describes a header feature. These are records used in pipe-mode that +contain information that otherwise would be in perf.data file's header. + + PERF_RECORD_COMPRESSED = 81, + +struct compressed_event { + struct perf_event_header header; + char data[]; +}; + +The header is followed by compressed data frame that can be decompressed +into array of perf trace records. The size of the entire compressed event +record including the header is limited by the max value of header.size. + +Event types + +Define the event attributes with their IDs. + +An array bound by the perf_file_section size. + + struct { + struct perf_event_attr attr; /* Size defined by header.attr_size */ + struct perf_file_section ids; + } + +ids points to a array of uint64_t defining the ids for event attr attr. + +Pipe-mode data + +Pipe-mode avoid seeks in the file by removing the perf_file_section and flags +from the struct perf_header. The trimmed header is: + +struct perf_pipe_file_header { + u64 magic; + u64 size; +}; + +The information about attrs, data, and event_types is instead in the +synthesized events PERF_RECORD_ATTR, PERF_RECORD_HEADER_TRACING_DATA, +PERF_RECORD_HEADER_EVENT_TYPE, and PERF_RECORD_HEADER_FEATURE +that are generated by perf record in pipe-mode. + + +References: + +include/uapi/linux/perf_event.h + +This is the canonical description of the kernel generated perf_events +and the perf_event_attrs. + +perf_events manpage + +A manpage describing perf_event and perf_event_attr is here: +http://web.eece.maine.edu/~vweaver/projects/perf_events/programming.html +This tends to be slightly behind the kernel include, but has better +descriptions. An (typically older) version of the man page may be +included with the standard Linux man pages, available with "man +perf_events" + +pmu-tools + +https://github.com/andikleen/pmu-tools/tree/master/parser + +A definition of the perf.data format in python "construct" format is available +in pmu-tools parser. This allows to read perf.data from python and dump it. + +quipper + +The quipper C++ parser is available at +http://github.com/google/perf_data_converter/tree/master/src/quipper + |