Perf File FormatKai

perf_file_header

a list of ids (u64 array)

a list of attributes (perf_file_attr)

data

a list of perf_file_section

(of optional features)

data of optional features

perf.data

perf_file_header->attrs->offset

perf_file_header->data->offset

perf_file_header->data->size

perf.datastruct perf_file_header { uint64_t magic; /* “PERFILE2” */ uint64_t size; /* sizeof(perf_file_header) */ uint64_t attr_size; /* sizeof(perf_file_attr) */ struct perf_file_section attrs; struct perf_file_section data; /* event_types is ignored, store zeros */ struct perf_file_section event_types; DECLARE_BITMAP(adds_features, HEADER_FEAT_BITS); };

struct perf_file_section { uint64_t offset; uint64_t size; };

perf_file_header->attrs->size

decided by perf_file_header->adds_features

perf_file_header

a list of ids (u64 array)

a list of attributes (perf_file_attr)

data

a list of perf_file_section

(of optional features)

data of optional features

perf_file_header

a list of ids (u64)

a list of attributes (perf_file_attr)

perf.datastruct perf_file_attr { struct perf_event_attr attr; struct perf_file_section ids; };

struct perf_file_section { uint64_t offset; uint64_t size; };

event0.id

event1.id

event2.id

event0.attrevent0.ids

event1.attrevent1.ids

event2.attrevent2.ids

event0.ids.offset

struct perf_event_attr { __u32 type; __u32 size; __u64 config;

union { __u64 sample_period; /* Period of sampling */ __u64 sample_freq; /* Frequency of sampling */ };

__u64 sample_type; /* Specifies values included in sample */ __u64 read_format; /* Specifies values returned in read */

/* 8<——8<——8<——8<——8<—— */ /* remove for clarity */ /* ——>8——>8——>8——>8——>8 */

union { __u32 wakeup_events; /* wakeup every n events */ __u32 wakeup_watermark; /* bytes before wakeup */ }; };

perf_file_header->attrs->offset

…

perf_file_header

a list of ids

a list of attributes

data

a list of perf_file_section

data of optional features

perf.datastruct perf_file_section { uint64_t offset; uint64_t size; };

feature0.section

feature1.section

feature0

feature1

feature0.section.offset

static const struct feature_ops feat_ops[HEADER_LAST_FEATURE] = { FEAT_OPP(HEADER_TRACING_DATA, tracing_data), FEAT_OPP(HEADER_BUILD_ID, build_id), FEAT_OPP(HEADER_HOSTNAME, hostname), FEAT_OPP(HEADER_OSRELEASE, osrelease), FEAT_OPP(HEADER_VERSION, version), FEAT_OPP(HEADER_ARCH, arch), FEAT_OPP(HEADER_NRCPUS, nrcpus), FEAT_OPP(HEADER_CPUDESC, cpudesc), FEAT_OPP(HEADER_CPUID, cpuid), FEAT_OPP(HEADER_TOTAL_MEM, total_mem), FEAT_OPP(HEADER_EVENT_DESC, event_desc), FEAT_OPP(HEADER_CMDLINE, cmdline), FEAT_OPF(HEADER_CPU_TOPOLOGY, cpu_topology), FEAT_OPF(HEADER_NUMA_TOPOLOGY, numa_topology), FEAT_OPA(HEADER_BRANCH_STACK, branch_stack), FEAT_OPP(HEADER_PMU_MAPPINGS, pmu_mappings), FEAT_OPP(HEADER_GROUP_DESC, group_desc), FEAT_OPP(HEADER_AUXTRACE, auxtrace), FEAT_OPA(HEADER_STAT, stat), };

perf_file_header

a list of ids (u64 array)

a list of attributes (perf_file_attr)

data

a list of perf_file_section

(of optional features)

data of optional features

perf.datastruct perf_event_header { __u32 type; __u16 misc; __u16 size; };

event0.header

event0

event1.header

event1

event2.header

event2

event3.header

event3

event4.header

event4

enum perf_event_type {

PERF_RECORD_MMAP = 1, PERF_RECORD_LOST = 2, PERF_RECORD_COMM = 3, PERF_RECORD_EXIT = 4, PERF_RECORD_THROTTLE = 5, PERF_RECORD_UNTHROTTLE = 6, PERF_RECORD_FORK = 7, PERF_RECORD_READ = 8, PERF_RECORD_SAMPLE = 9, PERF_RECORD_MMAP2 = 10, PERF_RECORD_AUX = 11, PERF_RECORD_ITRACE_START = 12, PERF_RECORD_LOST_SAMPLES = 13, PERF_RECORD_SWITCH = 14, PERF_RECORD_SWITCH_CPU_WIDE = 15,

PERF_RECORD_MAX, /* non-ABI */ }

according to perf_event_header.type

struct perf_event_attr { __u32 type; /* Type of event */ __u32 size; /* Size of attribute structure */ __u64 config; /* Type-specific configuration */

union { __u64 sample_period; /* Period of sampling */ __u64 sample_freq; /* Frequency of sampling */ };

__u64 sample_type; /* Specifies values included in sample */ __u64 read_format; /* Specifies values returned in read */

__u64 disabled : 1, /* off by default */ inherit : 1, /* children inherit it */ pinned : 1, /* must always be on PMU */ exclusive : 1, /* only group on PMU */ exclude_user : 1, /* don't count user */ exclude_kernel : 1, /* don't count kernel */ exclude_hv : 1, /* don't count hypervisor */ exclude_idle : 1, /* don't count when idle */ mmap : 1, /* include mmap data */ comm : 1, /* include comm data */ freq : 1, /* use freq, not period */ inherit_stat : 1, /* per task counts */ enable_on_exec : 1, /* next exec enables */ task : 1, /* trace fork/exit */ watermark : 1, /* wakeup_watermark */ precise_ip : 2, /* skid constraint */ mmap_data : 1, /* non-exec mmap data */ sample_id_all : 1, /* sample_type all events */ exclude_host : 1, /* don't count in host */ exclude_guest : 1, /* don't count in guest */ exclude_callchain_kernel : 1, /* exclude kernel callchains */ exclude_callchain_user : 1, /* exclude user callchains */

Reference• Perf source code

• libpfm source code

• perf_event_open manpage

• http://man7.org/linux/man-pages/man2/perf_event_open.2.html

• perf.data file format specification draft

• https://lwn.net/Articles/644919/

• perf file format (CERN openlab)

• https://openlab-mu-internal.web.cern.ch/openlab-mu-internal/03_Documents/3_Technical_Documents/Technical_Reports/2011/Urs_Fassler_report.pdf