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