1LIBPFM(3) Linux Programmer's Manual LIBPFM(3)
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6 pfm_get_event_info - get event information
7
9 #include <perfmon/pfmlib.h>
10 int pfm_get_event_info(int idx, pfm_os_t os, pfm_event_info_t *info);
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15 This function returns in info information about a specific event desig‐
16 nated by its opaque unique identifier in idx for the operating system
17 specified in os.
18 The pfm_event_info_t structure is defined as follows:
20 typedef struct {
21 const char *name;
22 const char *desc;
23 const char *equiv;
24 size_t size;
25 uint64_t code;
26 pfm_pmu_t pmu;
27 pfm_dtype_t dtype
28 int idx;
29 int nattrs;
30 struct {
31 unsigned int is_precise:1;
32 unsigned int reserved_bits:31;
33 };
34 } pfm_event_info_t;
35 The fields of this structure are defined as follows:
37 name This is the name of the event. This is a read-only string.
39 desc This is the description of the event. This is a read-only
41 string. It may contain multiple sentences.
42 equiv Certain events may be just variations of actual events. They may
44 be provided as handy shortcuts to avoid supplying a long list of
45 attributes. For those events, this field is not NULL and con‐
46 tains the complete equivalent event string.
47 code This is the raw event code. It should not be confused with the
49 encoding of the event. This field represents only the event
50 selection code, it does not include any unit mask or attribute
51 settings.
52 pmu This is the identification of the PMU model this event belongs
54 to. It is of type pfm_pmu_t. Using this value and the
55 pfm_get_pmu_info function, it is possible to get PMU informa‐
56 tion.
57 dtype This field returns the representation of the event data. By
59 default, it is PFM_DATA_UINT64.
60 idx This is the event unique opaque identifier. It is identical
62 to the idx passed to the call and is provided for completeness.
63 nattrs This is the number of attributes supported by this event.
65 Attributes may be unit masks or modifiers. If the event has not
66 attribute, then the value of this field is simply 0.
67 size This field contains the size of the struct passed. This field is
69 used to provide for extensibility of the struct without compro‐
70 mising backward compatibility. The value should be set to
71 sizeof(pfm_event_info_t). If instead, a value of 0 is specified,
72 the library assumes the struct passed is identical to the first
73 ABI version which size is PFM_EVENT_INFO_ABI0. Thus, if fields
74 were added after the first ABI, they will not be set by the
75 library. The library does check that bytes beyond what is imple‐
76 mented are zeroes.
77 is_precise
79 This bitfield indicates whether or not the event support precise
80 sampling. Precise sampling is a hardware mechanism that avoids
81 instruction address skid when using interrupt-based sampling.
82 When the event has umasks, this field means that at least one
83 umask supports precise sampling. On Intel X86 processors, this
84 indicates whether the event supports Precise Event-Based Sam‐
85 pling (PEBS).
86 The pfm_os_t enumeration provides the following choices:
88 PFM_OS_NONE
90 The returned information pertains only to what the PMU hardware
91 exports. No operating system attributes is taken into account.
92 PFM_OS_PERF_EVENT
94 The returned information includes the actual PMU hardware and
95 the additional attributes exported by the perf_events kernel
96 interface. The perf_event attributes pertain only the PMU hard‐
97 ware. In case perf_events is not detected, an error is
98 returned.
99 PFM_OS_PERF_EVENT_EXT
101 The returned information includes all of what is already pro‐
102 vided by PFM_OS_PERF_EVENT plus all the software attributes con‐
103 trolled by perf_events, such as sampling period, precise sam‐
104 pling.
105
107 If successful, the function returns PFM_SUCCESS and event information
108 in info, otherwise it returns an error code.
109
111 PFMLIB_ERR_NOINIT
112 Library has not been initialized properly.
113 PFMLIB_ERR_INVAL
115 The idx argument is invalid or info is NULL or size is not zero.
116 PFMLIB_ERR_NOTSUPP
118 The requested os is not detected or supported.
119
121 Stephane Eranian <eranian@gmail.com>
122 December, 2009 LIBPFM(3)