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1 | #ifndef LTT_H |
2 | #define LTT_H |
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3 | |
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4 | |
5 | /* A trace is associated with a tracing session run on a single, possibly |
6 | multi-cpu, system. It is defined as a pathname to a directory containing |
7 | all the relevant trace files. All the tracefiles for a trace were |
8 | generated in a single system for the same time period by the same |
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9 | trace daemon. They simply contain different events. Typically a "control" |
10 | tracefile contains the important events (process creations and registering |
11 | tracing facilities) for all CPUs, and one file for each CPU contains all |
12 | the events for that CPU. All the tracefiles within the same trace directory |
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13 | then use the exact same id numbers for event types. |
14 | |
15 | A tracefile (ltt_tracefile) contains a list of events (ltt_event) sorted |
16 | by time for each CPU; events from different CPUs may be slightly out of |
17 | order, especially using the (possibly drifting) cycle counters as |
18 | time unit. |
19 | |
20 | A facility is a list of event types (ltt_eventtype), declared in a special |
21 | .event file. An associated checksum differentiates different facilities |
22 | which would have the same name but a different content (e.g., different |
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23 | versions). The .event files are stored within the trace directory, or |
24 | in the default path, and are accessed automatically upon opening a trace. |
25 | The list of facilities (and associated checksum) used in a trace |
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26 | must be known in order to properly decode the contained events. An event |
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27 | is usually stored in the "control" tracefile to denote each different |
28 | "facility used". |
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29 | |
30 | Event types (ltt_eventtype) refer to data types (ltt_type) describing |
31 | their content. The data types supported are integer and unsigned integer |
32 | (of various length), enumerations (a special form of unsigned integer), |
33 | floating point (of various length), fixed size arrays, sequence |
34 | (variable sized arrays), structures and null terminated strings. |
35 | The elements of arrays and sequences, and the data members for |
36 | structures, may be of any nested data type (ltt_type). |
37 | |
38 | An ltt_field is a special object to denote a specific, possibly nested, |
39 | field within an event type. Suppose an event type socket_connect is a |
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40 | structure containing two data members, source and destination, of type |
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41 | socket_address. Type socket_address contains two unsigned integer |
42 | data members, ip and port. An ltt_field is different from a data type |
43 | structure member since it can denote a specific nested field, like the |
44 | source port, and store associated access information (byte offset within |
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45 | the event data). The ltt_field objects are trace specific since the |
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46 | contained information (byte offsets) may vary with the architecture |
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47 | associated to the trace. */ |
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48 | |
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49 | typedef struct _ltt_trace ltt_trace; |
50 | |
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51 | typedef struct _ltt_tracefile ltt_tracefile; |
52 | |
53 | typedef struct _ltt_facility ltt_facility; |
54 | |
55 | typedef struct _ltt_eventtype ltt_eventtype; |
56 | |
57 | typedef struct _ltt_type ltt_type; |
58 | |
59 | typedef struct _ltt_field ltt_field; |
60 | |
61 | typedef struct _ltt_event ltt_event; |
62 | |
63 | |
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64 | /* Checksums are used to differentiate facilities which have the same name |
65 | but differ. */ |
66 | |
67 | typedef unsigned long ltt_checksum; |
68 | |
69 | |
70 | /* Events are usually stored with the easily obtained CPU clock cycle count, |
71 | ltt_cycle_count. This can be converted to the real time value, ltt_time, |
72 | using linear interpolation between regularly sampled values (e.g. a few |
73 | times per second) of the real time clock with their corresponding |
74 | cycle count values. */ |
75 | |
76 | typedef struct timespec ltt_time; |
77 | |
78 | typedef uint64_t ltt_cycle_count; |
79 | |
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80 | |
81 | /* Differences between architectures include word sizes, endianess, |
82 | alignment, floating point format and calling conventions. For a |
83 | packed binary trace, endianess and size matter, assuming that the |
84 | floating point format is standard (and is seldom used anyway). */ |
85 | |
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86 | typedef enum _ltt_arch_size |
87 | { LTT_LP32, LTT_ILP32, LTT_LP64, LTT_ILP64, LTT_UNKNOWN |
88 | } ltt_arch_size; |
89 | |
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90 | |
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91 | typedef enum _ltt_arch_endian |
92 | { LTT_LITTLE_ENDIAN, LTT_BIG_ENDIAN |
93 | } ltt_arch_endian; |
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94 | |
95 | |
96 | |
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97 | #include <ltt/ltt-private.h> |
98 | |
99 | |
100 | #endif // LTT_H |