From: Ian Rogers Date: Sat, 4 Apr 2026 03:43:01 +0000 (-0700) Subject: perf sample: Document struct perf_sample X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8a7a23b27d55e036c2c54438d75878cf24bf95f6;p=thirdparty%2Fkernel%2Flinux.git perf sample: Document struct perf_sample Add kernel-doc for struct perf_sample capturing the somewhat unusual population of fields and lifetime relationships. Signed-off-by: Ian Rogers Signed-off-by: Namhyung Kim --- diff --git a/tools/perf/util/sample.h b/tools/perf/util/sample.h index 3cce8dd202aa9..9febad1c8207a 100644 --- a/tools/perf/util/sample.h +++ b/tools/perf/util/sample.h @@ -81,47 +81,148 @@ struct simd_flags { #define SIMD_OP_FLAGS_PRED_PARTIAL 0x01 /* partial predicate */ #define SIMD_OP_FLAGS_PRED_EMPTY 0x02 /* empty predicate */ +/** + * struct perf_sample + * + * A sample is generally filled in by evlist__parse_sample/evsel__parse_sample + * which fills in the variables from a "union perf_event *event" which is data + * from a perf ring buffer or perf.data file. The "event" sample is variable in + * length as determined by the perf_event_attr (in the evsel) and details within + * the sample event itself. A struct perf_sample avoids needing to care about + * the variable length nature of the original event. + * + * To avoid being excessively large parts of the struct perf_sample are pointers + * into the original sample event. In general the lifetime of a struct + * perf_sample needs to be less than the "union perf_event *event" it was + * derived from. + * + * The struct regs_dump user_regs and intr_regs are lazily allocated again for + * size reasons, due to them holding a cache of looked up registers. The + * function pair of perf_sample__init and perf_sample__exit correctly initialize + * and clean up these values. + */ struct perf_sample { + /** @ip: The sample event PERF_SAMPLE_IP value. */ u64 ip; - u32 pid, tid; + /** @pid: The sample event PERF_SAMPLE_TID pid value. */ + u32 pid; + /** @tid: The sample event PERF_SAMPLE_TID tid value. */ + u32 tid; + /** @time: The sample event PERF_SAMPLE_TIME value. */ u64 time; + /** @addr: The sample event PERF_SAMPLE_ADDR value. */ u64 addr; + /** @id: The sample event PERF_SAMPLE_ID or PEF_SAMPLE_IDENTIFIER value. */ u64 id; + /** @stream_id: The sample event PERF_SAMPLE_STREAM_ID value. */ u64 stream_id; + /** @period: The sample event PERF_SAMPLE_PERIOD value. */ u64 period; + /** @weight: Data determined by PERF_SAMPLE_WEIGHT or PERF_SAMPLE_WEIGHT_STRUCT. */ u64 weight; + /** @transaction: The sample event PERF_SAMPLE_TRANSACTION value. */ u64 transaction; + /** @insn_cnt: Filled in and used by intel-pt. */ u64 insn_cnt; + /** @cyc_cnt: Filled in and used by intel-pt. */ u64 cyc_cnt; + /** @cpu: The sample event PERF_SAMPLE_CPU value. */ u32 cpu; + /** + * @raw_size: The size in bytes of raw data from PERF_SAMPLE_RAW. For + * alignment reasons this should always be sizeof(u32) + * followed by a multiple of sizeof(u64). + */ u32 raw_size; + /** @data_src: The sample event PERF_SAMPLE_DATA_SRC value. */ u64 data_src; + /** @phys_addr: The sample event PERF_SAMPLE_PHYS_ADDR value. */ u64 phys_addr; + /** @data_page_size: The sample event PERF_SAMPLE_DATA_PAGE_SIZE value. */ u64 data_page_size; + /** @code_page_size: The sample event PERF_SAMPLE_CODE_PAGE_SIZE value. */ u64 code_page_size; + /** @cgroup: The sample event PERF_SAMPLE_CGROUP value. */ u64 cgroup; + /** @flags: Extra flag data from auxiliary events like intel-pt. */ u32 flags; + /** @machine_pid: The guest machine pid derived from the sample id. */ u32 machine_pid; + /** @vcpu: The guest machine vcpu derived from the sample id. */ u32 vcpu; + /** + * @insn_len: Instruction length from auxiliary events like + * intel-pt. The instruction itself is held in insn. + */ u16 insn_len; + /** + * @cpumode: The cpumode from struct perf_event_header misc variable + * masked with CPUMODE_MASK. Gives user, kernel and hypervisor + * information. + */ u8 cpumode; + /** @misc: The entire struct perf_event_header misc variable. */ u16 misc; + /** + * @ins_lat: Instruction latency information from weight2 in + * PERF_SAMPLE_WEIGHT_STRUCT or auxiliary events like + * intel-pt. + */ u16 ins_lat; - /** @weight3: On x86 holds retire_lat, on powerpc holds p_stage_cyc. */ + /** + * @weight3: From PERF_SAMPLE_WEIGHT_STRUCT. On x86 holds retire_lat, on + * powerpc holds p_stage_cyc. + */ u16 weight3; - bool no_hw_idx; /* No hw_idx collected in branch_stack */ - bool deferred_callchain; /* Has deferred user callchains */ + /** + * @no_hw_idx: For PERF_SAMPLE_BRANCH_STACK, true when + * PERF_SAMPLE_BRANCH_HW_INDEX isn't set. + */ + bool no_hw_idx; + /** + * @deferred_callchain: When processing PERF_SAMPLE_CALLCHAIN a deferred + * user callchain marker was encountered. + */ + bool deferred_callchain; + /** + * @deferred_cookie: Identifier of the deferred callchain in the later + * PERF_RECORD_CALLCHAIN_DEFERRED event. + */ u64 deferred_cookie; + /** @insn: A copy of the sampled instruction filled in by perf_sample__fetch_insn. */ char insn[MAX_INSN]; + /** @raw_data: Pointer into the original event for PERF_SAMPLE_RAW data. */ void *raw_data; + /** + * @callchain: Pointer into the original event for PERF_SAMPLE_CALLCHAIN + * data. For deferred callchains this may be a copy that + * needs freeing, see sample__merge_deferred_callchain. + */ struct ip_callchain *callchain; + /** @branch_stack: Pointer into the original event for PERF_SAMPLE_BRANCH_STACK data. */ struct branch_stack *branch_stack; + /** + * @branch_stack_cntr: Pointer into the original event for + * PERF_SAMPLE_BRANCH_COUNTERS data. + */ u64 *branch_stack_cntr; + /** @user_regs: Values and pointers into the sample for PERF_SAMPLE_REGS_USER. */ struct regs_dump *user_regs; + /** @intr_regs: Values and pointers into the sample for PERF_SAMPLE_REGS_INTR. */ struct regs_dump *intr_regs; + /** @user_stack: Size and pointer into the sample for PERF_SAMPLE_STACK_USER. */ struct stack_dump user_stack; + /** + * @read: The sample event PERF_SAMPLE_READ counter values. The valid + * values depend on the attr.read_format PERF_FORMAT_ values. + */ struct sample_read read; + /** + * @aux_sample: Similar to raw data but with a 64-bit size and + * alignment, PERF_SAMPLE_AUX data. + */ struct aux_sample aux_sample; + /** @simd_flags: SIMD flag information from ARM SPE auxiliary events. */ struct simd_flags simd_flags; };