Homec4science
Diffusion gbench-stream (master) Browse

gbench-stream/benchmark/src/perf_counters.cc
85d64a1de69fmaster

Last Change
Raw File

perf_counters.cc
View Options

// Copyright 2021 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "perf_counters.h"
#include <cstring>
#include <memory>
#include <vector>
#if defined HAVE_LIBPFM
#include "perfmon/pfmlib.h"
#include "perfmon/pfmlib_perf_event.h"
#endif
namespace benchmark {
namespace internal {
constexpr size_t PerfCounterValues::kMaxCounters;
#if defined HAVE_LIBPFM
const bool PerfCounters::kSupported = true;
bool PerfCounters::Initialize() { return pfm_initialize() == PFM_SUCCESS; }
PerfCounters PerfCounters::Create(
const std::vector<std::string>& counter_names) {
if (counter_names.empty()) {
return NoCounters();
}
if (counter_names.size() > PerfCounterValues::kMaxCounters) {
GetErrorLogInstance()
<< counter_names.size()
<< " counters were requested. The minimum is 1, the maximum is "
<< PerfCounterValues::kMaxCounters << "\n";
return NoCounters();
}
std::vector<int> counter_ids(counter_names.size());
const int mode = PFM_PLM3; // user mode only
for (size_t i = 0; i < counter_names.size(); ++i) {
const bool is_first = i == 0;
struct perf_event_attr attr {};
attr.size = sizeof(attr);
const int group_id = !is_first ? counter_ids[0] : -1;
const auto& name = counter_names[i];
if (name.empty()) {
GetErrorLogInstance() << "A counter name was the empty string\n";
return NoCounters();
}
pfm_perf_encode_arg_t arg{};
arg.attr = &attr;
const int pfm_get =
pfm_get_os_event_encoding(name.c_str(), mode, PFM_OS_PERF_EVENT, &arg);
if (pfm_get != PFM_SUCCESS) {
GetErrorLogInstance() << "Unknown counter name: " << name << "\n";
return NoCounters();
}
attr.disabled = is_first;
// Note: the man page for perf_event_create suggests inerit = true and
// read_format = PERF_FORMAT_GROUP don't work together, but that's not the
// case.
attr.inherit = true;
attr.pinned = is_first;
attr.exclude_kernel = true;
attr.exclude_user = false;
attr.exclude_hv = true;
// Read all counters in one read.
attr.read_format = PERF_FORMAT_GROUP;
int id = -1;
static constexpr size_t kNrOfSyscallRetries = 5;
// Retry syscall as it was interrupted often (b/64774091).
for (size_t num_retries = 0; num_retries < kNrOfSyscallRetries;
++num_retries) {
id = perf_event_open(&attr, 0, -1, group_id, 0);
if (id >= 0 || errno != EINTR) {
break;
}
}
if (id < 0) {
GetErrorLogInstance()
<< "Failed to get a file descriptor for " << name << "\n";
return NoCounters();
}
counter_ids[i] = id;
}
if (ioctl(counter_ids[0], PERF_EVENT_IOC_ENABLE) != 0) {
GetErrorLogInstance() << "Failed to start counters\n";
return NoCounters();
}
return PerfCounters(counter_names, std::move(counter_ids));
}
void PerfCounters::CloseCounters() const {
if (counter_ids_.empty()) {
return;
}
ioctl(counter_ids_[0], PERF_EVENT_IOC_DISABLE);
for (int fd : counter_ids_) {
close(fd);
}
}
#else // defined HAVE_LIBPFM
const bool PerfCounters::kSupported = false;
bool PerfCounters::Initialize() { return false; }
PerfCounters PerfCounters::Create(
const std::vector<std::string>& counter_names) {
if (!counter_names.empty()) {
GetErrorLogInstance() << "Performance counters not supported.";
}
return NoCounters();
}
void PerfCounters::CloseCounters() const {}
#endif // defined HAVE_LIBPFM
Mutex PerfCountersMeasurement::mutex_;
int PerfCountersMeasurement::ref_count_ = 0;
PerfCounters PerfCountersMeasurement::counters_ = PerfCounters::NoCounters();
PerfCountersMeasurement::PerfCountersMeasurement(
const std::vector<std::string>& counter_names)
: start_values_(counter_names.size()), end_values_(counter_names.size()) {
MutexLock l(mutex_);
if (ref_count_ == 0) {
counters_ = PerfCounters::Create(counter_names);
}
// We chose to increment it even if `counters_` ends up invalid,
// so that we don't keep trying to create, and also since the dtor
// will decrement regardless of `counters_`'s validity
++ref_count_;
BM_CHECK(!counters_.IsValid() || counters_.names() == counter_names);
}
PerfCountersMeasurement::~PerfCountersMeasurement() {
MutexLock l(mutex_);
--ref_count_;
if (ref_count_ == 0) {
counters_ = PerfCounters::NoCounters();
}
}
PerfCounters& PerfCounters::operator=(PerfCounters&& other) noexcept {
if (this != &other) {
CloseCounters();
counter_ids_ = std::move(other.counter_ids_);
counter_names_ = std::move(other.counter_names_);
}
return *this;
}
} // namespace internal
} // namespace benchmark
c4science · Help