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Diffstat (limited to 'tools/perf/Documentation/perf.data-file-format.txt')
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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 000000000000..fdc99fe6bbc3 --- /dev/null +++ b/tools/perf/Documentation/perf.data-file-format.txt @@ -0,0 +1,442 @@ +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 not described here. The pipe version can be converted to +normal perf.data with 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: + +The header is followed by different optional headers, described by the bits set +in flags. Only headers for which the bit is set are included. Each header +consists of a perf_file_section located after the initial header. +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_online; + uint32_t nr_cpus_available; /* CPUs not yet onlined */ +}; + + 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 bytes. + + HEADER_CMDLINE = 11, + +A perf_header_string with the perf command line 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, + +String lists defining the core and CPU threads topology. + +struct { + struct perf_header_string_list cores; /* Variable length */ + struct perf_header_string_list threads; /* Variable length */ +}; + +Example: + sibling cores : 0-3 + sibling threads : 0-1 + sibling threads : 2-3 + + 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]; +}; + + 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 ambigious. +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, /* depreceated */ + +#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]; +}; + +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. + +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 +https://chromium.googlesource.com/chromiumos/platform/chromiumos-wide-profiling/ +Unfortunately this parser tends to be many versions behind and may not be able +to parse data files generated by recent perf. |