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PiperOrigin-RevId: 253489161
2019-06-16 16:06:57 -07:00
commit d68f5e4169
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+// Copyright 2019 The MediaPipe Authors.
+//
+// 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 "mediapipe/util/cpu_util.h"
+
+#include <cmath>
+
+#ifdef __ANDROID__
+#include "ndk/sources/android/cpufeatures/cpu-features.h"
+#else
+#include <unistd.h>
+#endif
+#include <fstream>
+
+#include "absl/algorithm/container.h"
+#include "absl/strings/numbers.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/substitute.h"
+#include "mediapipe/framework/port/canonical_errors.h"
+#include "mediapipe/framework/port/integral_types.h"
+#include "mediapipe/framework/port/statusor.h"
+
+namespace mediapipe {
+namespace {
+
+constexpr uint32 kBufferLength = 64;
+
+::mediapipe::StatusOr<std::string> GetFilePath(int cpu) {
+  return absl::Substitute(
+      "/sys/devices/system/cpu/cpu$0/cpufreq/cpuinfo_max_freq", cpu);
+}
+
+::mediapipe::StatusOr<uint64> GetCpuMaxFrequency(int cpu) {
+  auto path_or_status = GetFilePath(cpu);
+  if (!path_or_status.ok()) {
+    return path_or_status.status();
+  }
+  std::ifstream file;
+  file.open(path_or_status.ValueOrDie());
+  if (file.is_open()) {
+    char buffer[kBufferLength];
+    file.getline(buffer, kBufferLength);
+    file.close();
+    uint64 frequency;
+    if (absl::SimpleAtoi(buffer, &frequency)) {
+      return frequency;
+    } else {
+      return mediapipe::InvalidArgumentError(
+          absl::StrCat("Invalid frequency: ", buffer));
+    }
+  } else {
+    return mediapipe::NotFoundError(
+        absl::StrCat("Couldn't read ", path_or_status.ValueOrDie()));
+  }
+}
+
+std::set<int> InferLowerOrHigherCoreIds(bool lower) {
+  std::vector<std::pair<int, uint64>> cpu_freq_pairs;
+  for (int cpu = 0; cpu < NumCPUCores(); ++cpu) {
+    auto freq_or_status = GetCpuMaxFrequency(cpu);
+    if (freq_or_status.ok()) {
+      cpu_freq_pairs.push_back({cpu, freq_or_status.ValueOrDie()});
+    }
+  }
+  if (cpu_freq_pairs.empty()) {
+    return {};
+  }
+
+  absl::c_sort(cpu_freq_pairs, [lower](const std::pair<int, uint64>& left,
+                                       const std::pair<int, uint64>& right) {
+    return (lower && left.second < right.second) ||
+           (!lower && left.second > right.second);
+  });
+  uint64 edge_freq = cpu_freq_pairs[0].second;
+
+  std::set<int> inferred_cores;
+  for (const auto& cpu_freq_pair : cpu_freq_pairs) {
+    if ((lower && cpu_freq_pair.second > edge_freq) ||
+        (!lower && cpu_freq_pair.second < edge_freq)) {
+      break;
+    }
+    inferred_cores.insert(cpu_freq_pair.first);
+  }
+
+  // If all the cores have the same frequency, there are no "lower" or "higher"
+  // cores.
+  if (inferred_cores.size() == cpu_freq_pairs.size()) {
+    return {};
+  } else {
+    return inferred_cores;
+  }
+}
+}  // namespace
+
+int NumCPUCores() {
+#ifdef __ANDROID__
+  return android_getCpuCount();
+#else
+  return sysconf(_SC_NPROCESSORS_ONLN);
+#endif
+}
+
+std::set<int> InferLowerCoreIds() {
+  return InferLowerOrHigherCoreIds(/* lower= */ true);
+}
+
+std::set<int> InferHigherCoreIds() {
+  return InferLowerOrHigherCoreIds(/* lower= */ false);
+}
+
+}  // namespace mediapipe.