1 /* Copyright 2016 The TensorFlow Authors. All Rights Reserved. 2 3 Licensed under the Apache License, Version 2.0 (the "License"); 4 you may not use this file except in compliance with the License. 5 You may obtain a copy of the License at 6 7 http://www.apache.org/licenses/LICENSE-2.0 8 9 Unless required by applicable law or agreed to in writing, software 10 distributed under the License is distributed on an "AS IS" BASIS, 11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 See the License for the specific language governing permissions and 13 limitations under the License. 14 ==============================================================================*/ 15 16 // Class method definitions for HostStream, the Stream implementation for 17 // the HostExecutor implementation. 18 #include "tensorflow/stream_executor/host/host_stream.h" 19 20 #include "absl/synchronization/notification.h" 21 #include "tensorflow/core/platform/denormal.h" 22 #include "tensorflow/core/platform/setround.h" 23 24 namespace stream_executor { 25 namespace host { 26 27 namespace { 28 GetThreadOptions(size_t stack_size_in_bytes)29port::ThreadOptions GetThreadOptions(size_t stack_size_in_bytes) { 30 port::ThreadOptions options; 31 options.stack_size = stack_size_in_bytes; 32 return options; 33 } 34 35 } // namespace 36 HostStream(size_t stack_size_in_bytes)37HostStream::HostStream(size_t stack_size_in_bytes) 38 : thread_(port::Env::Default()->StartThread( 39 GetThreadOptions(stack_size_in_bytes), "host_executor", 40 [this]() { WorkLoop(); })) {} 41 ~HostStream()42HostStream::~HostStream() { 43 { 44 absl::MutexLock lock(&mu_); 45 work_queue_.push(nullptr); 46 } 47 // thread_'s destructor blocks until the thread finishes running. 48 thread_.reset(); 49 } 50 EnqueueTask(std::function<void ()> fn)51bool HostStream::EnqueueTask(std::function<void()> fn) { 52 CHECK(fn != nullptr); 53 absl::MutexLock lock(&mu_); 54 work_queue_.push(std::move(fn)); 55 return true; 56 } 57 WorkAvailable()58bool HostStream::WorkAvailable() { return !work_queue_.empty(); } 59 WorkLoop()60void HostStream::WorkLoop() { 61 // Set denormal and rounding behavior to match the default TF ThreadPool 62 // behavior. 63 // TODO(phawkins, jlebar): it's not clear this is the best place to set this. 64 tensorflow::port::ScopedFlushDenormal flush; 65 tensorflow::port::ScopedSetRound round(FE_TONEAREST); 66 while (true) { 67 std::function<void()> fn; 68 { 69 absl::MutexLock lock(&mu_); 70 mu_.Await(absl::Condition(this, &HostStream::WorkAvailable)); 71 fn = std::move(work_queue_.front()); 72 work_queue_.pop(); 73 } 74 if (!fn) { 75 return; 76 } 77 fn(); 78 } 79 } 80 BlockUntilDone()81void HostStream::BlockUntilDone() { 82 absl::Notification done; 83 EnqueueTask([&done]() { done.Notify(); }); 84 done.WaitForNotification(); 85 } 86 87 } // namespace host 88 89 } // namespace stream_executor 90