llvm/tools/llvm-xray/xray-account.cpp

   1 //===- xray-account.h - XRay Function Call Accounting ---------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements basic function call accounting from an XRay trace.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include <algorithm>
  14 #include <cassert>
  15 #include <numeric>
  16 #include <system_error>
  17 #include <utility>
  18
  19 #include "xray-account.h"
  20 #include "xray-registry.h"
  21 #include "llvm/Support/ErrorHandling.h"
  22 #include "llvm/Support/FormatVariadic.h"
  23 #include "llvm/XRay/InstrumentationMap.h"
  24 #include "llvm/XRay/Trace.h"
  25
  26 using namespace llvm;
  27 using namespace llvm::xray;
  28
  29 static cl::SubCommand Account("account", "Function call accounting");
  30 static cl::opt<std::string> AccountInput(cl::Positional,
  31                                          cl::desc("<xray log file>"),
  32                                          cl::Required, cl::sub(Account));
  33 static cl::opt<bool>
  34     AccountKeepGoing("keep-going", cl::desc("Keep going on errors encountered"),
  35                      cl::sub(Account), cl::init(false));
  36 static cl::alias AccountKeepGoing2("k", cl::aliasopt(AccountKeepGoing),
  37                                    cl::desc("Alias for -keep_going"));
  38 static cl::opt<bool> AccountRecursiveCallsOnly(
  39     "recursive-calls-only", cl::desc("Only count the calls that are recursive"),
  40     cl::sub(Account), cl::init(false));
  41 static cl::opt<bool> AccountDeduceSiblingCalls(
  42     "deduce-sibling-calls",
  43     cl::desc("Deduce sibling calls when unrolling function call stacks"),
  44     cl::sub(Account), cl::init(false));
  45 static cl::alias
  46     AccountDeduceSiblingCalls2("d", cl::aliasopt(AccountDeduceSiblingCalls),
  47                                cl::desc("Alias for -deduce_sibling_calls"));
  48 static cl::opt<std::string>
  49     AccountOutput("output", cl::value_desc("output file"), cl::init("-"),
  50                   cl::desc("output file; use '-' for stdout"),
  51                   cl::sub(Account));
  52 static cl::alias AccountOutput2("o", cl::aliasopt(AccountOutput),
  53                                 cl::desc("Alias for -output"));
  54 enum class AccountOutputFormats { TEXT, CSV };
  55 static cl::opt<AccountOutputFormats>
  56     AccountOutputFormat("format", cl::desc("output format"),
  57                         cl::values(clEnumValN(AccountOutputFormats::TEXT,
  58                                               "text", "report stats in text"),
  59                                    clEnumValN(AccountOutputFormats::CSV, "csv",
  60                                               "report stats in csv")),
  61                         cl::sub(Account));
  62 static cl::alias AccountOutputFormat2("f", cl::desc("Alias of -format"),
  63                                       cl::aliasopt(AccountOutputFormat));
  64
  65 enum class SortField {
  66   FUNCID,
  67   COUNT,
  68   MIN,
  69   MED,
  70   PCT90,
  71   PCT99,
  72   MAX,
  73   SUM,
  74   FUNC,
  75 };
  76
  77 static cl::opt<SortField> AccountSortOutput(
  78     "sort", cl::desc("sort output by this field"), cl::value_desc("field"),
  79     cl::sub(Account), cl::init(SortField::FUNCID),
  80     cl::values(clEnumValN(SortField::FUNCID, "funcid", "function id"),
  81                clEnumValN(SortField::COUNT, "count", "funciton call counts"),
  82                clEnumValN(SortField::MIN, "min", "minimum function durations"),
  83                clEnumValN(SortField::MED, "med", "median function durations"),
  84                clEnumValN(SortField::PCT90, "90p", "90th percentile durations"),
  85                clEnumValN(SortField::PCT99, "99p", "99th percentile durations"),
  86                clEnumValN(SortField::MAX, "max", "maximum function durations"),
  87                clEnumValN(SortField::SUM, "sum", "sum of call durations"),
  88                clEnumValN(SortField::FUNC, "func", "function names")));
  89 static cl::alias AccountSortOutput2("s", cl::aliasopt(AccountSortOutput),
  90                                     cl::desc("Alias for -sort"));
  91
  92 enum class SortDirection {
  93   ASCENDING,
  94   DESCENDING,
  95 };
  96 static cl::opt<SortDirection> AccountSortOrder(
  97     "sortorder", cl::desc("sort ordering"), cl::init(SortDirection::ASCENDING),
  98     cl::values(clEnumValN(SortDirection::ASCENDING, "asc", "ascending"),
  99                clEnumValN(SortDirection::DESCENDING, "dsc", "descending")),
 100     cl::sub(Account));
 101 static cl::alias AccountSortOrder2("r", cl::aliasopt(AccountSortOrder),
 102                                    cl::desc("Alias for -sortorder"));
 103
 104 static cl::opt<int> AccountTop("top", cl::desc("only show the top N results"),
 105                                cl::value_desc("N"), cl::sub(Account),
 106                                cl::init(-1));
 107 static cl::alias AccountTop2("p", cl::desc("Alias for -top"),
 108                              cl::aliasopt(AccountTop));
 109
 110 static cl::opt<std::string>
 111     AccountInstrMap("instr_map",
 112                     cl::desc("binary with the instrumentation map, or "
 113                              "a separate instrumentation map"),
 114                     cl::value_desc("binary with xray_instr_map"),
 115                     cl::sub(Account), cl::init(""));
 116 static cl::alias AccountInstrMap2("m", cl::aliasopt(AccountInstrMap),
 117                                   cl::desc("Alias for -instr_map"));
 118
 119 namespace {
 120
 121 template <class T, class U> void setMinMax(std::pair<T, T> &MM, U &&V) {
 122   if (MM.first == 0 || MM.second == 0)
 123     MM = std::make_pair(std::forward<U>(V), std::forward<U>(V));
 124   else
 125     MM = std::make_pair(std::min(MM.first, V), std::max(MM.second, V));
 126 }
 127
 128 template <class T> T diff(T L, T R) { return std::max(L, R) - std::min(L, R); }
 129
 130 } // namespace
 131
 132 using RecursionStatus = LatencyAccountant::FunctionStack::RecursionStatus;
 133 RecursionStatus &RecursionStatus::operator++() {
 134   auto Depth = Bitfield::get<RecursionStatus::Depth>(Storage);
 135   assert(Depth >= 0 && Depth < std::numeric_limits<decltype(Depth)>::max());
 136   ++Depth;
 137   Bitfield::set<RecursionStatus::Depth>(Storage, Depth); // ++Storage
 138   // Did this function just (maybe indirectly) call itself the first time?
 139   if (!isRecursive() && Depth == 2) // Storage == 2  /  Storage s> 1
 140     Bitfield::set<RecursionStatus::IsRecursive>(Storage,
 141                                                 true); // Storage |= INT_MIN
 142   return *this;
 143 }
 144 RecursionStatus &RecursionStatus::operator--() {
 145   auto Depth = Bitfield::get<RecursionStatus::Depth>(Storage);
 146   assert(Depth > 0);
 147   --Depth;
 148   Bitfield::set<RecursionStatus::Depth>(Storage, Depth); // --Storage
 149   // Did we leave a function that previouly (maybe indirectly) called itself?
 150   if (isRecursive() && Depth == 0) // Storage == INT_MIN
 151     Bitfield::set<RecursionStatus::IsRecursive>(Storage, false); // Storage = 0
 152   return *this;
 153 }
 154 bool RecursionStatus::isRecursive() const {
 155   return Bitfield::get<RecursionStatus::IsRecursive>(Storage); // Storage s< 0
 156 }
 157
 158 bool LatencyAccountant::accountRecord(const XRayRecord &Record) {
 159   setMinMax(PerThreadMinMaxTSC[Record.TId], Record.TSC);
 160   setMinMax(PerCPUMinMaxTSC[Record.CPU], Record.TSC);
 161
 162   if (CurrentMaxTSC == 0)
 163     CurrentMaxTSC = Record.TSC;
 164
 165   if (Record.TSC < CurrentMaxTSC)
 166     return false;
 167
 168   auto &ThreadStack = PerThreadFunctionStack[Record.TId];
 169   if (RecursiveCallsOnly && !ThreadStack.RecursionDepth)
 170     ThreadStack.RecursionDepth.emplace();
 171   switch (Record.Type) {
 172   case RecordTypes::CUSTOM_EVENT:
 173   case RecordTypes::TYPED_EVENT:
 174     // TODO: Support custom and typed event accounting in the future.
 175     return true;
 176   case RecordTypes::ENTER:
 177   case RecordTypes::ENTER_ARG: {
 178     ThreadStack.Stack.emplace_back(Record.FuncId, Record.TSC);
 179     if (ThreadStack.RecursionDepth)
 180       ++(*ThreadStack.RecursionDepth)[Record.FuncId];
 181     break;
 182   }
 183   case RecordTypes::EXIT:
 184   case RecordTypes::TAIL_EXIT: {
 185     if (ThreadStack.Stack.empty())
 186       return false;
 187
 188     if (ThreadStack.Stack.back().first == Record.FuncId) {
 189       const auto &Top = ThreadStack.Stack.back();
 190       if (!ThreadStack.RecursionDepth ||
 191           (*ThreadStack.RecursionDepth)[Top.first].isRecursive())
 192         recordLatency(Top.first, diff(Top.second, Record.TSC));
 193       if (ThreadStack.RecursionDepth)
 194         --(*ThreadStack.RecursionDepth)[Top.first];
 195       ThreadStack.Stack.pop_back();
 196       break;
 197     }
 198
 199     if (!DeduceSiblingCalls)
 200       return false;
 201
 202     // Look for the parent up the stack.
 203     auto Parent =
 204         std::find_if(ThreadStack.Stack.rbegin(), ThreadStack.Stack.rend(),
 205                      [&](const std::pair<const int32_t, uint64_t> &E) {
 206                        return E.first == Record.FuncId;
 207                      });
 208     if (Parent == ThreadStack.Stack.rend())
 209       return false;
 210
 211     // Account time for this apparently sibling call exit up the stack.
 212     // Considering the following case:
 213     //
 214     //   f()
 215     //    g()
 216     //      h()
 217     //
 218     // We might only ever see the following entries:
 219     //
 220     //   -> f()
 221     //   -> g()
 222     //   -> h()
 223     //   <- h()
 224     //   <- f()
 225     //
 226     // Now we don't see the exit to g() because some older version of the XRay
 227     // runtime wasn't instrumenting tail exits. If we don't deduce tail calls,
 228     // we may potentially never account time for g() -- and this code would have
 229     // already bailed out, because `<- f()` doesn't match the current "top" of
 230     // stack where we're waiting for the exit to `g()` instead. This is not
 231     // ideal and brittle -- so instead we provide a potentially inaccurate
 232     // accounting of g() instead, computing it from the exit of f().
 233     //
 234     // While it might be better that we account the time between `-> g()` and
 235     // `-> h()` as the proper accounting of time for g() here, this introduces
 236     // complexity to do correctly (need to backtrack, etc.).
 237     //
 238     // FIXME: Potentially implement the more complex deduction algorithm?
 239     auto R = make_range(std::next(Parent).base(), ThreadStack.Stack.end());
 240     for (auto &E : R) {
 241       if (!ThreadStack.RecursionDepth ||
 242           (*ThreadStack.RecursionDepth)[E.first].isRecursive())
 243         recordLatency(E.first, diff(E.second, Record.TSC));
 244     }
 245     for (auto &Top : reverse(R)) {
 246       if (ThreadStack.RecursionDepth)
 247         --(*ThreadStack.RecursionDepth)[Top.first];
 248       ThreadStack.Stack.pop_back();
 249     }
 250     break;
 251   }
 252   }
 253
 254   return true;
 255 }
 256
 257 namespace {
 258
 259 // We consolidate the data into a struct which we can output in various forms.
 260 struct ResultRow {
 261   uint64_t Count;
 262   double Min;
 263   double Median;
 264   double Pct90;
 265   double Pct99;
 266   double Max;
 267   double Sum;
 268   std::string DebugInfo;
 269   std::string Function;
 270 };
 271
 272 ResultRow getStats(MutableArrayRef<uint64_t> Timings) {
 273   assert(!Timings.empty());
 274   ResultRow R;
 275   R.Sum = std::accumulate(Timings.begin(), Timings.end(), 0.0);
 276   auto MinMax = std::minmax_element(Timings.begin(), Timings.end());
 277   R.Min = *MinMax.first;
 278   R.Max = *MinMax.second;
 279   R.Count = Timings.size();
 280
 281   auto MedianOff = Timings.size() / 2;
 282   std::nth_element(Timings.begin(), Timings.begin() + MedianOff, Timings.end());
 283   R.Median = Timings[MedianOff];
 284
 285   auto Pct90Off = std::floor(Timings.size() * 0.9);
 286   std::nth_element(Timings.begin(), Timings.begin() + (uint64_t)Pct90Off,
 287                    Timings.end());
 288   R.Pct90 = Timings[Pct90Off];
 289
 290   auto Pct99Off = std::floor(Timings.size() * 0.99);
 291   std::nth_element(Timings.begin(), Timings.begin() + (uint64_t)Pct99Off,
 292                    Timings.end());
 293   R.Pct99 = Timings[Pct99Off];
 294   return R;
 295 }
 296
 297 } // namespace
 298
 299 using TupleType = std::tuple<int32_t, uint64_t, ResultRow>;
 300
 301 template <typename F>
 302 static void sortByKey(std::vector<TupleType> &Results, F Fn) {
 303   bool ASC = AccountSortOrder == SortDirection::ASCENDING;
 304   llvm::sort(Results, [=](const TupleType &L, const TupleType &R) {
 305     return ASC ? Fn(L) < Fn(R) : Fn(L) > Fn(R);
 306   });
 307 }
 308
 309 template <class F>
 310 void LatencyAccountant::exportStats(const XRayFileHeader &Header, F Fn) const {
 311   std::vector<TupleType> Results;
 312   Results.reserve(FunctionLatencies.size());
 313   for (auto FT : FunctionLatencies) {
 314     const auto &FuncId = FT.first;
 315     auto &Timings = FT.second;
 316     Results.emplace_back(FuncId, Timings.size(), getStats(Timings));
 317     auto &Row = std::get<2>(Results.back());
 318     if (Header.CycleFrequency) {
 319       double CycleFrequency = Header.CycleFrequency;
 320       Row.Min /= CycleFrequency;
 321       Row.Median /= CycleFrequency;
 322       Row.Pct90 /= CycleFrequency;
 323       Row.Pct99 /= CycleFrequency;
 324       Row.Max /= CycleFrequency;
 325       Row.Sum /= CycleFrequency;
 326     }
 327
 328     Row.Function = FuncIdHelper.SymbolOrNumber(FuncId);
 329     Row.DebugInfo = FuncIdHelper.FileLineAndColumn(FuncId);
 330   }
 331
 332   // Sort the data according to user-provided flags.
 333   switch (AccountSortOutput) {
 334   case SortField::FUNCID:
 335     sortByKey(Results, [](const TupleType &X) { return std::get<0>(X); });
 336     break;
 337   case SortField::COUNT:
 338     sortByKey(Results, [](const TupleType &X) { return std::get<1>(X); });
 339     break;
 340   case SortField::MIN:
 341     sortByKey(Results, [](const TupleType &X) { return std::get<2>(X).Min; });
 342     break;
 343   case SortField::MED:
 344     sortByKey(Results, [](const TupleType &X) { return std::get<2>(X).Median; });
 345     break;
 346   case SortField::PCT90:
 347     sortByKey(Results, [](const TupleType &X) { return std::get<2>(X).Pct90; });
 348     break;
 349   case SortField::PCT99:
 350     sortByKey(Results, [](const TupleType &X) { return std::get<2>(X).Pct99; });
 351     break;
 352   case SortField::MAX:
 353     sortByKey(Results, [](const TupleType &X) { return std::get<2>(X).Max; });
 354     break;
 355   case SortField::SUM:
 356     sortByKey(Results, [](const TupleType &X) { return std::get<2>(X).Sum; });
 357     break;
 358   case SortField::FUNC:
 359     llvm_unreachable("Not implemented");
 360   }
 361
 362   if (AccountTop > 0) {
 363     auto MaxTop =
 364         std::min(AccountTop.getValue(), static_cast<int>(Results.size()));
 365     Results.erase(Results.begin() + MaxTop, Results.end());
 366   }
 367
 368   for (const auto &R : Results)
 369     Fn(std::get<0>(R), std::get<1>(R), std::get<2>(R));
 370 }
 371
 372 void LatencyAccountant::exportStatsAsText(raw_ostream &OS,
 373                                           const XRayFileHeader &Header) const {
 374   OS << "Functions with latencies: " << FunctionLatencies.size() << "\n";
 375
 376   // We spend some effort to make the text output more readable, so we do the
 377   // following formatting decisions for each of the fields:
 378   //
 379   //   - funcid: 32-bit, but we can determine the largest number and be
 380   //   between
 381   //     a minimum of 5 characters, up to 9 characters, right aligned.
 382   //   - count:  64-bit, but we can determine the largest number and be
 383   //   between
 384   //     a minimum of 5 characters, up to 9 characters, right aligned.
 385   //   - min, median, 90pct, 99pct, max: double precision, but we want to keep
 386   //     the values in seconds, with microsecond precision (0.000'001), so we
 387   //     have at most 6 significant digits, with the whole number part to be
 388   //     at
 389   //     least 1 character. For readability we'll right-align, with full 9
 390   //     characters each.
 391   //   - debug info, function name: we format this as a concatenation of the
 392   //     debug info and the function name.
 393   //
 394   static constexpr char StatsHeaderFormat[] =
 395       "{0,+9} {1,+10} [{2,+9}, {3,+9}, {4,+9}, {5,+9}, {6,+9}] {7,+9}";
 396   static constexpr char StatsFormat[] =
 397       R"({0,+9} {1,+10} [{2,+9:f6}, {3,+9:f6}, {4,+9:f6}, {5,+9:f6}, {6,+9:f6}] {7,+9:f6})";
 398   OS << llvm::formatv(StatsHeaderFormat, "funcid", "count", "min", "med", "90p",
 399                       "99p", "max", "sum")
 400      << llvm::formatv("  {0,-12}\n", "function");
 401   exportStats(Header, [&](int32_t FuncId, size_t Count, const ResultRow &Row) {
 402     OS << llvm::formatv(StatsFormat, FuncId, Count, Row.Min, Row.Median,
 403                         Row.Pct90, Row.Pct99, Row.Max, Row.Sum)
 404        << "  " << Row.DebugInfo << ": " << Row.Function << "\n";
 405   });
 406 }
 407
 408 void LatencyAccountant::exportStatsAsCSV(raw_ostream &OS,
 409                                          const XRayFileHeader &Header) const {
 410   OS << "funcid,count,min,median,90%ile,99%ile,max,sum,debug,function\n";
 411   exportStats(Header, [&](int32_t FuncId, size_t Count, const ResultRow &Row) {
 412     OS << FuncId << ',' << Count << ',' << Row.Min << ',' << Row.Median << ','
 413        << Row.Pct90 << ',' << Row.Pct99 << ',' << Row.Max << "," << Row.Sum
 414        << ",\"" << Row.DebugInfo << "\",\"" << Row.Function << "\"\n";
 415   });
 416 }
 417
 418 using namespace llvm::xray;
 419
 420 namespace llvm {
 421 template <> struct format_provider<llvm::xray::RecordTypes> {
 422   static void format(const llvm::xray::RecordTypes &T, raw_ostream &Stream,
 423                      StringRef Style) {
 424     switch (T) {
 425     case RecordTypes::ENTER:
 426       Stream << "enter";
 427       break;
 428     case RecordTypes::ENTER_ARG:
 429       Stream << "enter-arg";
 430       break;
 431     case RecordTypes::EXIT:
 432       Stream << "exit";
 433       break;
 434     case RecordTypes::TAIL_EXIT:
 435       Stream << "tail-exit";
 436       break;
 437     case RecordTypes::CUSTOM_EVENT:
 438       Stream << "custom-event";
 439       break;
 440     case RecordTypes::TYPED_EVENT:
 441       Stream << "typed-event";
 442       break;
 443     }
 444   }
 445 };
 446 } // namespace llvm
 447
 448 static CommandRegistration Unused(&Account, []() -> Error {
 449   InstrumentationMap Map;
 450   if (!AccountInstrMap.empty()) {
 451     auto InstrumentationMapOrError = loadInstrumentationMap(AccountInstrMap);
 452     if (!InstrumentationMapOrError)
 453       return joinErrors(make_error<StringError>(
 454                             Twine("Cannot open instrumentation map '") +
 455                                 AccountInstrMap + "'",
 456                             std::make_error_code(std::errc::invalid_argument)),
 457                         InstrumentationMapOrError.takeError());
 458     Map = std::move(*InstrumentationMapOrError);
 459   }
 460
 461   std::error_code EC;
 462   raw_fd_ostream OS(AccountOutput, EC, sys::fs::OpenFlags::OF_TextWithCRLF);
 463   if (EC)
 464     return make_error<StringError>(
 465         Twine("Cannot open file '") + AccountOutput + "' for writing.", EC);
 466
 467   const auto &FunctionAddresses = Map.getFunctionAddresses();
 468   symbolize::LLVMSymbolizer Symbolizer;
 469   llvm::xray::FuncIdConversionHelper FuncIdHelper(AccountInstrMap, Symbolizer,
 470                                                   FunctionAddresses);
 471   xray::LatencyAccountant FCA(FuncIdHelper, AccountRecursiveCallsOnly,
 472                               AccountDeduceSiblingCalls);
 473   auto TraceOrErr = loadTraceFile(AccountInput);
 474   if (!TraceOrErr)
 475     return joinErrors(
 476         make_error<StringError>(
 477             Twine("Failed loading input file '") + AccountInput + "'",
 478             std::make_error_code(std::errc::executable_format_error)),
 479         TraceOrErr.takeError());
 480
 481   auto &T = *TraceOrErr;
 482   for (const auto &Record : T) {
 483     if (FCA.accountRecord(Record))
 484       continue;
 485     errs()
 486         << "Error processing record: "
 487         << llvm::formatv(
 488                R"({{type: {0}; cpu: {1}; record-type: {2}; function-id: {3}; tsc: {4}; thread-id: {5}; process-id: {6}}})",
 489                Record.RecordType, Record.CPU, Record.Type, Record.FuncId,
 490                Record.TSC, Record.TId, Record.PId)
 491         << '\n';
 492     for (const auto &ThreadStack : FCA.getPerThreadFunctionStack()) {
 493       errs() << "Thread ID: " << ThreadStack.first << "\n";
 494       if (ThreadStack.second.Stack.empty()) {
 495         errs() << "  (empty stack)\n";
 496         continue;
 497       }
 498       auto Level = ThreadStack.second.Stack.size();
 499       for (const auto &Entry : llvm::reverse(ThreadStack.second.Stack))
 500         errs() << "  #" << Level-- << "\t"
 501                << FuncIdHelper.SymbolOrNumber(Entry.first) << '\n';
 502     }
 503     if (!AccountKeepGoing)
 504       return make_error<StringError>(
 505           Twine("Failed accounting function calls in file '") + AccountInput +
 506               "'.",
 507           std::make_error_code(std::errc::executable_format_error));
 508   }
 509   switch (AccountOutputFormat) {
 510   case AccountOutputFormats::TEXT:
 511     FCA.exportStatsAsText(OS, T.getFileHeader());
 512     break;
 513   case AccountOutputFormats::CSV:
 514     FCA.exportStatsAsCSV(OS, T.getFileHeader());
 515     break;
 516   }
 517
 518   return Error::success();
 519 });