tools/llvm-exegesis/lib/PerfHelper.cpp

   1 //===-- PerfHelper.cpp ------------------------------------------*- C++ -*-===//
   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 #include "PerfHelper.h"
  10 #include "llvm/Config/config.h"
  11 #include "llvm/Support/raw_ostream.h"
  12 #ifdef HAVE_LIBPFM
  13 #include "perfmon/perf_event.h"
  14 #include "perfmon/pfmlib.h"
  15 #include "perfmon/pfmlib_perf_event.h"
  16 #endif
  17 #include <cassert>
  18
  19 namespace llvm {
  20 namespace exegesis {
  21 namespace pfm {
  22
  23 #ifdef HAVE_LIBPFM
  24 static bool isPfmError(int Code) { return Code != PFM_SUCCESS; }
  25 #endif
  26
  27 bool pfmInitialize() {
  28 #ifdef HAVE_LIBPFM
  29   return isPfmError(pfm_initialize());
  30 #else
  31   return true;
  32 #endif
  33 }
  34
  35 void pfmTerminate() {
  36 #ifdef HAVE_LIBPFM
  37   pfm_terminate();
  38 #endif
  39 }
  40
  41 PerfEvent::~PerfEvent() {
  42 #ifdef HAVE_LIBPFM
  43   delete Attr;
  44   ;
  45 #endif
  46 }
  47
  48 PerfEvent::PerfEvent(PerfEvent &&Other)
  49     : EventString(std::move(Other.EventString)),
  50       FullQualifiedEventString(std::move(Other.FullQualifiedEventString)),
  51       Attr(Other.Attr) {
  52   Other.Attr = nullptr;
  53 }
  54
  55 PerfEvent::PerfEvent(llvm::StringRef PfmEventString)
  56     : EventString(PfmEventString.str()), Attr(nullptr) {
  57 #ifdef HAVE_LIBPFM
  58   char *Fstr = nullptr;
  59   pfm_perf_encode_arg_t Arg = {};
  60   Attr = new perf_event_attr();
  61   Arg.attr = Attr;
  62   Arg.fstr = &Fstr;
  63   Arg.size = sizeof(pfm_perf_encode_arg_t);
  64   const int Result = pfm_get_os_event_encoding(EventString.c_str(), PFM_PLM3,
  65                                                PFM_OS_PERF_EVENT, &Arg);
  66   if (isPfmError(Result)) {
  67     // We don't know beforehand which counters are available (e.g. 6 uops ports
  68     // on Sandybridge but 8 on Haswell) so we report the missing counter without
  69     // crashing.
  70     llvm::errs() << pfm_strerror(Result) << " - cannot create event "
  71                  << EventString << "\n";
  72   }
  73   if (Fstr) {
  74     FullQualifiedEventString = Fstr;
  75     free(Fstr);
  76   }
  77 #endif
  78 }
  79
  80 llvm::StringRef PerfEvent::name() const { return EventString; }
  81
  82 bool PerfEvent::valid() const { return !FullQualifiedEventString.empty(); }
  83
  84 const perf_event_attr *PerfEvent::attribute() const { return Attr; }
  85
  86 llvm::StringRef PerfEvent::getPfmEventString() const {
  87   return FullQualifiedEventString;
  88 }
  89
  90 #ifdef HAVE_LIBPFM
  91 Counter::Counter(const PerfEvent &Event) {
  92   assert(Event.valid());
  93   const pid_t Pid = 0;    // measure current process/thread.
  94   const int Cpu = -1;     // measure any processor.
  95   const int GroupFd = -1; // no grouping of counters.
  96   const uint32_t Flags = 0;
  97   perf_event_attr AttrCopy = *Event.attribute();
  98   FileDescriptor = perf_event_open(&AttrCopy, Pid, Cpu, GroupFd, Flags);
  99   if (FileDescriptor == -1) {
 100     llvm::errs() << "Unable to open event, make sure your kernel allows user "
 101                     "space perf monitoring.\nYou may want to try:\n$ sudo sh "
 102                     "-c 'echo -1 > /proc/sys/kernel/perf_event_paranoid'\n";
 103   }
 104   assert(FileDescriptor != -1 && "Unable to open event");
 105 }
 106
 107 Counter::~Counter() { close(FileDescriptor); }
 108
 109 void Counter::start() { ioctl(FileDescriptor, PERF_EVENT_IOC_RESET, 0); }
 110
 111 void Counter::stop() { ioctl(FileDescriptor, PERF_EVENT_IOC_DISABLE, 0); }
 112
 113 int64_t Counter::read() const {
 114   int64_t Count = 0;
 115   ssize_t ReadSize = ::read(FileDescriptor, &Count, sizeof(Count));
 116   if (ReadSize != sizeof(Count)) {
 117     Count = -1;
 118     llvm::errs() << "Failed to read event counter\n";
 119   }
 120   return Count;
 121 }
 122
 123 #else
 124
 125 Counter::Counter(const PerfEvent &Event) {}
 126
 127 Counter::~Counter() = default;
 128
 129 void Counter::start() {}
 130
 131 void Counter::stop() {}
 132
 133 int64_t Counter::read() const { return 42; }
 134
 135 #endif
 136
 137 } // namespace pfm
 138 } // namespace exegesis
 139 } // namespace llvm