| 1 | #LyX 1.5.5 created this file. For more info see http://www.lyx.org/ |
| 2 | \lyxformat 276 |
| 3 | \begin_document |
| 4 | \begin_header |
| 5 | \textclass article |
| 6 | \language english |
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| 27 | \tocdepth 3 |
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| 29 | \defskip medskip |
| 30 | \quotes_language english |
| 31 | \papercolumns 1 |
| 32 | \papersides 1 |
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| 34 | \tracking_changes false |
| 35 | \output_changes false |
| 36 | \author "" |
| 37 | \author "" |
| 38 | \end_header |
| 39 | |
| 40 | \begin_body |
| 41 | |
| 42 | \begin_layout Title |
| 43 | A Set of APIs for a Third-Generation Trace Viewer |
| 44 | \end_layout |
| 45 | |
| 46 | \begin_layout Author |
| 47 | \noindent |
| 48 | Pierre-Marc Fournier, Michel Dagenais, Mathieu Desnoyers |
| 49 | \newline |
| 50 | |
| 51 | \family typewriter |
| 52 | \size footnotesize |
| 53 | <pierre-marc.fournier _at_ polymtl.ca> |
| 54 | \family default |
| 55 | \size default |
| 56 | |
| 57 | \newline |
| 58 | |
| 59 | \newline |
| 60 | CASI Lab |
| 61 | \newline |
| 62 | École Polytechnique de Montréal |
| 63 | \newline |
| 64 | |
| 65 | \newline |
| 66 | WORK IN PROGRESS |
| 67 | \end_layout |
| 68 | |
| 69 | \begin_layout Section |
| 70 | Introduction |
| 71 | \end_layout |
| 72 | |
| 73 | \begin_layout Standard |
| 74 | This document proposes some APIs for a trace viewing and analysis infrastructure. |
| 75 | \end_layout |
| 76 | |
| 77 | \begin_layout Standard |
| 78 | Design choices were made based on the experience acquired by the design, |
| 79 | development and use of two previous generations of trace viewers, respectively |
| 80 | the Trace Visualizer from the Linux Trace Toolkit and its successor, the |
| 81 | LTTV from the LTTng tracing toolkit. |
| 82 | \end_layout |
| 83 | |
| 84 | \begin_layout Section |
| 85 | Goals |
| 86 | \end_layout |
| 87 | |
| 88 | \begin_layout Itemize |
| 89 | Provide an infrastructure for fast, interactive visualization and analysis |
| 90 | of huge traces (>10 GB) on standard workstations |
| 91 | \begin_inset Foot |
| 92 | status open |
| 93 | |
| 94 | \begin_layout Standard |
| 95 | Efficiency is of great importance. |
| 96 | It is tempting to think that as computers get faster, it will be possible |
| 97 | to run more complex analyses on traces in a shorter time. |
| 98 | In fact, the size of the traces grows as computers get more powerful, because |
| 99 | they do more operations than before in the same amount of time and therefore |
| 100 | generate more events. |
| 101 | The current tendency to parallelize systems is another factor that results |
| 102 | in bigger traces. |
| 103 | \end_layout |
| 104 | |
| 105 | \end_inset |
| 106 | |
| 107 | |
| 108 | \end_layout |
| 109 | |
| 110 | \begin_layout Itemize |
| 111 | Support live trace processing |
| 112 | \end_layout |
| 113 | |
| 114 | \begin_layout Itemize |
| 115 | Allow merging of traces of different formats |
| 116 | \end_layout |
| 117 | |
| 118 | \begin_layout Standard |
| 119 | \begin_inset Note Note |
| 120 | status open |
| 121 | |
| 122 | \begin_layout Itemize |
| 123 | Design the viewer in such a way that it can run in parallel on multi-core |
| 124 | systems |
| 125 | \begin_inset Note Greyedout |
| 126 | status open |
| 127 | |
| 128 | \begin_layout Standard |
| 129 | (Is it worth it? Beware of complex locking issues) |
| 130 | \end_layout |
| 131 | |
| 132 | \end_inset |
| 133 | |
| 134 | ; No, we don't. |
| 135 | \end_layout |
| 136 | |
| 137 | \end_inset |
| 138 | |
| 139 | |
| 140 | \end_layout |
| 141 | |
| 142 | \begin_layout Itemize |
| 143 | Design with both command line utilities (C language) and graphical interfaces |
| 144 | (Java and others) in mind, sharing code and standardizing interfaces as |
| 145 | much as possible |
| 146 | \end_layout |
| 147 | |
| 148 | \begin_deeper |
| 149 | \begin_layout Standard |
| 150 | Both command-line interfaces and graphical interfaces have an important |
| 151 | role to play in trace analysis. |
| 152 | While graphical interfaces allow for complex views, command-line utilities |
| 153 | can be used quickly in more environments; they can also be more convenient |
| 154 | in some circumstances. |
| 155 | A good design should be such that they can share code and APIs. |
| 156 | \end_layout |
| 157 | |
| 158 | \end_deeper |
| 159 | \begin_layout Section |
| 160 | General aspects |
| 161 | \end_layout |
| 162 | |
| 163 | \begin_layout Itemize |
| 164 | All data structures must be accessed through API methods, in order to allow |
| 165 | for internal change without breaking compatibility. |
| 166 | \end_layout |
| 167 | |
| 168 | \begin_layout Section |
| 169 | Controlling the tracing of a system |
| 170 | \end_layout |
| 171 | |
| 172 | \begin_layout Subsection |
| 173 | Overview |
| 174 | \end_layout |
| 175 | |
| 176 | \begin_layout Standard |
| 177 | The goal of this API is to provide a portable way of controlling tracing |
| 178 | of heterogenous systems. |
| 179 | \end_layout |
| 180 | |
| 181 | \begin_layout Standard |
| 182 | It should enable to do the following actions. |
| 183 | \end_layout |
| 184 | |
| 185 | \begin_layout Itemize |
| 186 | Set the parameters of a trace (channels, buffering, destination of data |
| 187 | (file, network, process)...) |
| 188 | \end_layout |
| 189 | |
| 190 | \begin_layout Itemize |
| 191 | Control the recording of events (start, stop, pause the trace) |
| 192 | \end_layout |
| 193 | |
| 194 | \begin_layout Itemize |
| 195 | Create tracepoints (on dynamic tracers) and control which tracepoints are |
| 196 | activated (some may be at trace level, others might only permit system |
| 197 | level) |
| 198 | \end_layout |
| 199 | |
| 200 | \begin_layout Subsection |
| 201 | Trace control API |
| 202 | \end_layout |
| 203 | |
| 204 | \begin_layout Itemize |
| 205 | List the static tracepoints available on a system |
| 206 | \end_layout |
| 207 | |
| 208 | \begin_deeper |
| 209 | \begin_layout Standard |
| 210 | These may be static tracepoints (active or inactive) or dynamic tracepoints |
| 211 | (active or proposed). |
| 212 | \end_layout |
| 213 | |
| 214 | \end_deeper |
| 215 | \begin_layout Itemize |
| 216 | Add a new dynamic tracepoint |
| 217 | \end_layout |
| 218 | |
| 219 | \begin_layout Itemize |
| 220 | Activate a tracepoint |
| 221 | \end_layout |
| 222 | |
| 223 | \begin_layout Itemize |
| 224 | Deactivate a tracepoint |
| 225 | \end_layout |
| 226 | |
| 227 | \begin_layout Itemize |
| 228 | List available probes |
| 229 | \end_layout |
| 230 | |
| 231 | \begin_layout Itemize |
| 232 | Connect a probe to a tracepoint |
| 233 | \end_layout |
| 234 | |
| 235 | \begin_layout Itemize |
| 236 | Start tracing |
| 237 | \end_layout |
| 238 | |
| 239 | \begin_layout Itemize |
| 240 | Stop tracing |
| 241 | \end_layout |
| 242 | |
| 243 | \begin_layout Itemize |
| 244 | \begin_inset Note Greyedout |
| 245 | status open |
| 246 | |
| 247 | \begin_layout Standard |
| 248 | others missing... |
| 249 | \end_layout |
| 250 | |
| 251 | \end_inset |
| 252 | |
| 253 | |
| 254 | \end_layout |
| 255 | |
| 256 | \begin_layout Section |
| 257 | Reading traces |
| 258 | \end_layout |
| 259 | |
| 260 | \begin_layout Subsection |
| 261 | Overview |
| 262 | \end_layout |
| 263 | |
| 264 | \begin_layout Subsubsection |
| 265 | Timestamps |
| 266 | \end_layout |
| 267 | |
| 268 | \begin_layout Standard |
| 269 | Timestamps, at the framework level, should be in an architecture-independent |
| 270 | format. |
| 271 | One possibility would be to have them stored in seconds (with decimals). |
| 272 | Offsetting, if necessary, could be handled by the traceset (trace merging) |
| 273 | level. |
| 274 | An uncertainty value should accompany the timestamp. |
| 275 | Timestamps in cycles should be available if they are provided by the tracer. |
| 276 | \end_layout |
| 277 | |
| 278 | \begin_layout Subsection |
| 279 | Low-level trace reading API |
| 280 | \end_layout |
| 281 | |
| 282 | \begin_layout Standard |
| 283 | The goal of this API is to provide a uniform way for the framework to access |
| 284 | the events recorded in a trace, in an encoding-independant way. |
| 285 | \end_layout |
| 286 | |
| 287 | \begin_layout Subsubsection |
| 288 | Factory methods |
| 289 | \end_layout |
| 290 | |
| 291 | \begin_layout Itemize |
| 292 | void get_supported_formats(void) |
| 293 | \end_layout |
| 294 | |
| 295 | \begin_deeper |
| 296 | \begin_layout Standard |
| 297 | Arguments: none |
| 298 | \end_layout |
| 299 | |
| 300 | \begin_layout Standard |
| 301 | Return: |
| 302 | \end_layout |
| 303 | |
| 304 | \begin_layout Itemize |
| 305 | a list of supported formats |
| 306 | \end_layout |
| 307 | |
| 308 | \end_deeper |
| 309 | \begin_layout Itemize |
| 310 | open_trace() |
| 311 | \end_layout |
| 312 | |
| 313 | \begin_deeper |
| 314 | \begin_layout Standard |
| 315 | Arguments: |
| 316 | \end_layout |
| 317 | |
| 318 | \begin_layout Itemize |
| 319 | trace URL |
| 320 | \end_layout |
| 321 | |
| 322 | \begin_deeper |
| 323 | \begin_layout Itemize |
| 324 | local file name |
| 325 | \end_layout |
| 326 | |
| 327 | \begin_layout Itemize |
| 328 | other special url to establish a network connection |
| 329 | \end_layout |
| 330 | |
| 331 | \begin_layout Itemize |
| 332 | etc... |
| 333 | \end_layout |
| 334 | |
| 335 | \end_deeper |
| 336 | \begin_layout Itemize |
| 337 | trace format (optional, for cases where auto detection would not work or |
| 338 | be ambiguous) |
| 339 | \end_layout |
| 340 | |
| 341 | \begin_layout Standard |
| 342 | Return: |
| 343 | \end_layout |
| 344 | |
| 345 | \begin_layout Itemize |
| 346 | a trace handle |
| 347 | \end_layout |
| 348 | |
| 349 | \end_deeper |
| 350 | \begin_layout Subsubsection |
| 351 | Trace methods |
| 352 | \end_layout |
| 353 | |
| 354 | \begin_layout Itemize |
| 355 | bool close(struct trace *tr) |
| 356 | \end_layout |
| 357 | |
| 358 | \begin_layout Itemize |
| 359 | struct event *current_event(struct trace *) |
| 360 | \end_layout |
| 361 | |
| 362 | \begin_deeper |
| 363 | \begin_layout Standard |
| 364 | Arguments: none |
| 365 | \end_layout |
| 366 | |
| 367 | \begin_layout Standard |
| 368 | Return: |
| 369 | \end_layout |
| 370 | |
| 371 | \begin_layout Itemize |
| 372 | the event currently pointed by the position pointer |
| 373 | \end_layout |
| 374 | |
| 375 | \end_deeper |
| 376 | \begin_layout Itemize |
| 377 | bool advance(struct trace *tr) |
| 378 | \end_layout |
| 379 | |
| 380 | \begin_deeper |
| 381 | \begin_layout Standard |
| 382 | Advance the position pointer to the next event in the trace. |
| 383 | \end_layout |
| 384 | |
| 385 | \begin_layout Standard |
| 386 | Arguments: none |
| 387 | \end_layout |
| 388 | |
| 389 | \begin_layout Standard |
| 390 | Return values: |
| 391 | \end_layout |
| 392 | |
| 393 | \begin_layout Itemize |
| 394 | The result: |
| 395 | \end_layout |
| 396 | |
| 397 | \begin_deeper |
| 398 | \begin_layout Itemize |
| 399 | Success |
| 400 | \end_layout |
| 401 | |
| 402 | \begin_layout Itemize |
| 403 | Final end of trace (end of a non-live trace or of a completed live trace) |
| 404 | \end_layout |
| 405 | |
| 406 | \begin_layout Itemize |
| 407 | No more events for now (end of a still running live trace) |
| 408 | \end_layout |
| 409 | |
| 410 | \end_deeper |
| 411 | \end_deeper |
| 412 | \begin_layout Itemize |
| 413 | bool seek_time(struct trace *tr, struct trace_cursor *cur) |
| 414 | \end_layout |
| 415 | |
| 416 | \begin_deeper |
| 417 | \begin_layout Standard |
| 418 | Arguments: |
| 419 | \end_layout |
| 420 | |
| 421 | \begin_layout Itemize |
| 422 | The time to seek to |
| 423 | \end_layout |
| 424 | |
| 425 | \begin_layout Standard |
| 426 | Return: none |
| 427 | \end_layout |
| 428 | |
| 429 | \end_deeper |
| 430 | \begin_layout Itemize |
| 431 | struct trace_cursor *trace_new_cursor_beginning(struct trace *tr) |
| 432 | \end_layout |
| 433 | |
| 434 | \begin_deeper |
| 435 | \begin_layout Standard |
| 436 | Return a new cursor associated to the trace, positioned at its beginning |
| 437 | \end_layout |
| 438 | |
| 439 | \end_deeper |
| 440 | \begin_layout Itemize |
| 441 | struct trace_cursor *trace_cursor_copy(struct trace_cursor *cur) |
| 442 | \end_layout |
| 443 | |
| 444 | \begin_layout Itemize |
| 445 | void trace_cursor_destroy(struct trace_cursor_destroy *) |
| 446 | \end_layout |
| 447 | |
| 448 | \begin_layout Itemize |
| 449 | struct trace_time get_time_start(struct trace *tr) |
| 450 | \end_layout |
| 451 | |
| 452 | \begin_deeper |
| 453 | \begin_layout Standard |
| 454 | Arguments: none |
| 455 | \end_layout |
| 456 | |
| 457 | \begin_layout Standard |
| 458 | Return: |
| 459 | \end_layout |
| 460 | |
| 461 | \begin_layout Itemize |
| 462 | the timestamp of the first event in the trace |
| 463 | \end_layout |
| 464 | |
| 465 | \end_deeper |
| 466 | \begin_layout Itemize |
| 467 | struct trace_time get_time_end(struct trace *tr) |
| 468 | \end_layout |
| 469 | |
| 470 | \begin_deeper |
| 471 | \begin_layout Standard |
| 472 | Arguments: none |
| 473 | \end_layout |
| 474 | |
| 475 | \begin_layout Standard |
| 476 | Return: |
| 477 | \end_layout |
| 478 | |
| 479 | \begin_layout Itemize |
| 480 | the timestamp of the last event in the trace |
| 481 | \end_layout |
| 482 | |
| 483 | \end_deeper |
| 484 | \begin_layout Itemize |
| 485 | register_callback_new_event(struct trace *tr, struct trace_time after, void |
| 486 | (*cb)(void)) |
| 487 | \end_layout |
| 488 | |
| 489 | \begin_deeper |
| 490 | \begin_layout Standard |
| 491 | Register a callback that is called when a new event becomes available in |
| 492 | a live trace. |
| 493 | It is also called when the live trace ends. |
| 494 | \end_layout |
| 495 | |
| 496 | \begin_layout Standard |
| 497 | Arguments: |
| 498 | \end_layout |
| 499 | |
| 500 | \begin_layout Itemize |
| 501 | after (timestamp) : call only if the event occurent later than |
| 502 | \emph on |
| 503 | after |
| 504 | \end_layout |
| 505 | |
| 506 | \begin_layout Itemize |
| 507 | cb: the callback function |
| 508 | \begin_inset Note Note |
| 509 | status open |
| 510 | |
| 511 | \begin_layout Standard |
| 512 | specify its args and return val |
| 513 | \end_layout |
| 514 | |
| 515 | \end_inset |
| 516 | |
| 517 | |
| 518 | \end_layout |
| 519 | |
| 520 | \begin_layout Standard |
| 521 | Return: |
| 522 | \end_layout |
| 523 | |
| 524 | \begin_layout Itemize |
| 525 | Result (success or failure) |
| 526 | \end_layout |
| 527 | |
| 528 | \end_deeper |
| 529 | \begin_layout Subsection |
| 530 | High-level trace reading API |
| 531 | \end_layout |
| 532 | |
| 533 | \begin_layout Standard |
| 534 | The goal of this API is to provide a uniform way for analyses and views |
| 535 | to obtain trace events from a traceset (merge of many traces or a single |
| 536 | trace), regardless of the system they were recorded on and of the tracer |
| 537 | used. |
| 538 | \end_layout |
| 539 | |
| 540 | \begin_layout Itemize |
| 541 | Request a range of events |
| 542 | \end_layout |
| 543 | |
| 544 | \begin_deeper |
| 545 | \begin_layout Standard |
| 546 | Arguments: |
| 547 | \end_layout |
| 548 | |
| 549 | \begin_layout Itemize |
| 550 | (implicitly) the traceset |
| 551 | \end_layout |
| 552 | |
| 553 | \begin_layout Itemize |
| 554 | start timestamp |
| 555 | \end_layout |
| 556 | |
| 557 | \begin_layout Itemize |
| 558 | stop timestamp (special value for infinity, for live traces) |
| 559 | \end_layout |
| 560 | |
| 561 | \begin_layout Itemize |
| 562 | list of event types and callbacks |
| 563 | \end_layout |
| 564 | |
| 565 | \begin_layout Itemize |
| 566 | filter with complex expressions |
| 567 | \end_layout |
| 568 | |
| 569 | \begin_layout Itemize |
| 570 | private pointer to be passed to the callbacks |
| 571 | \end_layout |
| 572 | |
| 573 | \begin_layout Standard |
| 574 | Return: |
| 575 | \end_layout |
| 576 | |
| 577 | \begin_layout Itemize |
| 578 | handle to the request for cancelling it |
| 579 | \end_layout |
| 580 | |
| 581 | \end_deeper |
| 582 | \begin_layout Itemize |
| 583 | Cancel a request |
| 584 | \end_layout |
| 585 | |
| 586 | \begin_deeper |
| 587 | \begin_layout Standard |
| 588 | Arguments: |
| 589 | \end_layout |
| 590 | |
| 591 | \begin_layout Itemize |
| 592 | the handle to the request |
| 593 | \end_layout |
| 594 | |
| 595 | \end_deeper |
| 596 | \begin_layout Subsection |
| 597 | State management |
| 598 | \end_layout |
| 599 | |
| 600 | \begin_layout Subsubsection |
| 601 | State accessing API |
| 602 | \end_layout |
| 603 | |
| 604 | \begin_layout Itemize |
| 605 | Request the values of a given set of state variables at a point in time |
| 606 | \end_layout |
| 607 | |
| 608 | \begin_deeper |
| 609 | \begin_layout Standard |
| 610 | Arguments: |
| 611 | \end_layout |
| 612 | |
| 613 | \begin_layout Itemize |
| 614 | the list of state variables |
| 615 | \end_layout |
| 616 | |
| 617 | \begin_layout Itemize |
| 618 | the timestamp |
| 619 | \end_layout |
| 620 | |
| 621 | \end_deeper |
| 622 | \begin_layout Itemize |
| 623 | Request all the states changes of a given set of state variables between |
| 624 | two time indexes |
| 625 | \end_layout |
| 626 | |
| 627 | \begin_deeper |
| 628 | \begin_layout Standard |
| 629 | Arguments: |
| 630 | \end_layout |
| 631 | |
| 632 | \begin_layout Itemize |
| 633 | the list of state variables |
| 634 | \end_layout |
| 635 | |
| 636 | \begin_layout Itemize |
| 637 | timestamp 1 |
| 638 | \end_layout |
| 639 | |
| 640 | \begin_layout Itemize |
| 641 | timestamp 2 |
| 642 | \end_layout |
| 643 | |
| 644 | \end_deeper |
| 645 | \begin_layout Subsubsection |
| 646 | State setting API |
| 647 | \end_layout |
| 648 | |
| 649 | \begin_layout Section |
| 650 | Describing event types |
| 651 | \end_layout |
| 652 | |
| 653 | \begin_layout Subsection |
| 654 | Overview |
| 655 | \end_layout |
| 656 | |
| 657 | \begin_layout Standard |
| 658 | Because tracepoints may be created dynamically, information about the descriptio |
| 659 | n of events is just as dynamic. |
| 660 | In this context, one simple way to communicate the event description informatio |
| 661 | n to upper layers would be to send them as events, as it is done in recent |
| 662 | versions of LTTV. |
| 663 | The core events used to describe other events are the only ones whose descripti |
| 664 | on is hardcoded in the framework. |
| 665 | \end_layout |
| 666 | |
| 667 | \begin_layout Standard |
| 668 | These event-type-describing events could then be received and interpreted |
| 669 | by a module, the Event Description Service, which would be a client to |
| 670 | the high-level tracing API at the same level as normal views and analyses. |
| 671 | It would store the information and allow the other views and analyses to |
| 672 | access it via this API. |
| 673 | \end_layout |
| 674 | |
| 675 | \begin_layout Subsection |
| 676 | Events-describing events |
| 677 | \end_layout |
| 678 | |
| 679 | \begin_layout Itemize |
| 680 | Event type declaration event |
| 681 | \end_layout |
| 682 | |
| 683 | \begin_deeper |
| 684 | \begin_layout Standard |
| 685 | Announce the existence of an event type |
| 686 | \end_layout |
| 687 | |
| 688 | \begin_layout Itemize |
| 689 | event type name |
| 690 | \end_layout |
| 691 | |
| 692 | \end_deeper |
| 693 | \begin_layout Itemize |
| 694 | Argument declaration event |
| 695 | \end_layout |
| 696 | |
| 697 | \begin_deeper |
| 698 | \begin_layout Standard |
| 699 | Announce the existence of an event argument |
| 700 | \end_layout |
| 701 | |
| 702 | \begin_layout Itemize |
| 703 | event type name |
| 704 | \end_layout |
| 705 | |
| 706 | \begin_layout Itemize |
| 707 | name |
| 708 | \end_layout |
| 709 | |
| 710 | \begin_layout Itemize |
| 711 | type |
| 712 | \end_layout |
| 713 | |
| 714 | \end_deeper |
| 715 | \begin_layout Itemize |
| 716 | Event destruction |
| 717 | \end_layout |
| 718 | |
| 719 | \begin_deeper |
| 720 | \begin_layout Standard |
| 721 | Announce that an event type ceased to exist |
| 722 | \end_layout |
| 723 | |
| 724 | \begin_layout Itemize |
| 725 | event type name |
| 726 | \end_layout |
| 727 | |
| 728 | \end_deeper |
| 729 | \begin_layout Subsection |
| 730 | Event type description API |
| 731 | \end_layout |
| 732 | |
| 733 | \begin_layout Itemize |
| 734 | Get the list of all the event types |
| 735 | \end_layout |
| 736 | |
| 737 | \begin_layout Itemize |
| 738 | Find an event type by name |
| 739 | \end_layout |
| 740 | |
| 741 | \begin_layout Itemize |
| 742 | Get the number of arguments of an event |
| 743 | \end_layout |
| 744 | |
| 745 | \begin_layout Itemize |
| 746 | Get the list of arguments of an event |
| 747 | \end_layout |
| 748 | |
| 749 | \begin_layout Itemize |
| 750 | Find an argument by name |
| 751 | \end_layout |
| 752 | |
| 753 | \begin_layout Itemize |
| 754 | Get the type of an argument of an event type |
| 755 | \end_layout |
| 756 | |
| 757 | \begin_layout Itemize |
| 758 | Get a string representation of an argument of any type, given an event that |
| 759 | contains it an instance of it |
| 760 | \end_layout |
| 761 | |
| 762 | \begin_layout Itemize |
| 763 | Get an integer representation of an integer argument, a floating-point represent |
| 764 | ation of a floating-point argument |
| 765 | \end_layout |
| 766 | |
| 767 | \begin_layout Itemize |
| 768 | Functions for accessing other types |
| 769 | \end_layout |
| 770 | |
| 771 | \begin_layout Section |
| 772 | Inspecting events |
| 773 | \end_layout |
| 774 | |
| 775 | \begin_layout Subsection |
| 776 | Overview |
| 777 | \end_layout |
| 778 | |
| 779 | \begin_layout Standard |
| 780 | Events contain the following information. |
| 781 | \end_layout |
| 782 | |
| 783 | \begin_layout Itemize |
| 784 | Timestamp |
| 785 | \end_layout |
| 786 | |
| 787 | \begin_layout Itemize |
| 788 | Event type identifier |
| 789 | \end_layout |
| 790 | |
| 791 | \begin_deeper |
| 792 | \begin_layout Standard |
| 793 | Two possibilities: |
| 794 | \end_layout |
| 795 | |
| 796 | \begin_layout Itemize |
| 797 | an event id (integer) |
| 798 | \end_layout |
| 799 | |
| 800 | \begin_layout Itemize |
| 801 | an event name (string) |
| 802 | \end_layout |
| 803 | |
| 804 | \end_deeper |
| 805 | \begin_layout Itemize |
| 806 | The name of the machine it occured on |
| 807 | \end_layout |
| 808 | |
| 809 | \begin_layout Subsection |
| 810 | Event inspecting API |
| 811 | \end_layout |
| 812 | |
| 813 | \begin_layout Itemize |
| 814 | get the event type identifier |
| 815 | \end_layout |
| 816 | |
| 817 | \begin_layout Itemize |
| 818 | get timestamp |
| 819 | \end_layout |
| 820 | |
| 821 | \begin_layout Itemize |
| 822 | get the name of the machine on which the event occured |
| 823 | \end_layout |
| 824 | |
| 825 | \begin_layout Itemize |
| 826 | get information on the type of tracing technology that was used |
| 827 | \end_layout |
| 828 | |
| 829 | \begin_layout Itemize |
| 830 | get the corresponding tracepoint (machine/tracing technology/name/location |
| 831 | in code(if available)) |
| 832 | \end_layout |
| 833 | |
| 834 | \end_body |
| 835 | \end_document |