Compute Library
 21.08
IScheduler.h
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24 #ifndef ARM_COMPUTE_ISCHEDULER_H
25 #define ARM_COMPUTE_ISCHEDULER_H
26 
28 #include "arm_compute/core/Types.h"
30 
31 #include <functional>
32 #include <limits>
33 
34 namespace arm_compute
35 {
36 class ICPPKernel;
37 class ITensor;
38 class Window;
39 
40 /** Scheduler interface to run kernels */
42 {
43 public:
44  /** Strategies available to split a workload */
45  enum class StrategyHint
46  {
47  STATIC, /**< Split the workload evenly among the threads */
48  DYNAMIC, /**< Split the workload dynamically using a bucket system */
49  };
50 
51  /** Function to be used and map a given thread id to a logical core id
52  *
53  * Mapping function expects the thread index and total number of cores as input,
54  * and returns the logical core index to bind against
55  */
56  using BindFunc = std::function<int(int, int)>;
57 
58  /** When arm_compute::ISchedular::Hints::_split_dimension is initialized with this value
59  * then the schedular is free to break down the problem space over as many dimensions
60  * as it wishes
61  */
62  static constexpr unsigned int split_dimensions_all = std::numeric_limits<unsigned>::max();
63 
64  /** Scheduler hints
65  *
66  * Collection of preferences set by the function regarding how to split a given workload
67  */
68  class Hints
69  {
70  public:
71  /** Constructor
72  *
73  * @param[in] split_dimension Dimension along which to split the kernel's execution window.
74  * @param[in] strategy (Optional) Split strategy.
75  * @param[in] threshold (Optional) Dynamic scheduling capping threshold.
76  */
77  Hints(unsigned int split_dimension, StrategyHint strategy = StrategyHint::STATIC, int threshold = 0)
78  : _split_dimension(split_dimension), _strategy(strategy), _threshold(threshold)
79  {
80  }
81  /** Set the split_dimension hint
82  *
83  * @param[in] split_dimension Dimension along which to split the kernel's execution window.
84  *
85  * @return the Hints object
86  */
87  Hints &set_split_dimension(unsigned int split_dimension)
88  {
89  _split_dimension = split_dimension;
90  return *this;
91  }
92  /** Return the prefered split dimension
93  *
94  * @return The split dimension
95  */
96  unsigned int split_dimension() const
97  {
98  return _split_dimension;
99  }
100 
101  /** Set the strategy hint
102  *
103  * @param[in] strategy Prefered strategy to use to split the workload
104  *
105  * @return the Hints object
106  */
108  {
109  _strategy = strategy;
110  return *this;
111  }
112  /** Return the prefered strategy to use to split workload.
113  *
114  * @return The strategy
115  */
117  {
118  return _strategy;
119  }
120  /** Return the granule capping threshold to be used by dynamic scheduling.
121  *
122  * @return The capping threshold
123  */
124  int threshold() const
125  {
126  return _threshold;
127  }
128 
129  private:
130  unsigned int _split_dimension{};
131  StrategyHint _strategy{};
132  int _threshold{};
133  };
134  /** Signature for the workloads to execute */
135  using Workload = std::function<void(const ThreadInfo &)>;
136  /** Default constructor. */
137  IScheduler();
138 
139  /** Destructor. */
140  virtual ~IScheduler() = default;
141 
142  /** Sets the number of threads the scheduler will use to run the kernels.
143  *
144  * @param[in] num_threads If set to 0, then one thread per CPU core available on the system will be used, otherwise the number of threads specified.
145  */
146  virtual void set_num_threads(unsigned int num_threads) = 0;
147 
148  /** Sets the number of threads the scheduler will use to run the kernels but also using a binding function to pin the threads to given logical cores
149  *
150  * @param[in] num_threads If set to 0, then one thread per CPU core available on the system will be used, otherwise the number of threads specified.
151  * @param[in] func Binding function to use.
152  */
153  virtual void set_num_threads_with_affinity(unsigned int num_threads, BindFunc func);
154 
155  /** Returns the number of threads that the SingleThreadScheduler has in his pool.
156  *
157  * @return Number of threads available in SingleThreadScheduler.
158  */
159  virtual unsigned int num_threads() const = 0;
160 
161  /** Runs the kernel in the same thread as the caller synchronously.
162  *
163  * @param[in] kernel Kernel to execute.
164  * @param[in] hints Hints for the scheduler.
165  */
166  virtual void schedule(ICPPKernel *kernel, const Hints &hints) = 0;
167 
168  /** Runs the kernel in the same thread as the caller synchronously.
169  *
170  * @param[in] kernel Kernel to execute.
171  * @param[in] hints Hints for the scheduler.
172  * @param[in] window Window to use for kernel execution.
173  * @param[in] tensors Vector containing the tensors to operate on.
174  */
175  virtual void schedule_op(ICPPKernel *kernel, const Hints &hints, const Window &window, ITensorPack &tensors) = 0;
176 
177  /** Execute all the passed workloads
178  *
179  * @note there is no guarantee regarding the order in which the workloads will be executed or whether or not they will be executed in parallel.
180  *
181  * @param[in] workloads Array of workloads to run
182  * @param[in] tag String that can be used by profiling tools to identify the workloads run by the scheduler (Can be null).
183  */
184  virtual void run_tagged_workloads(std::vector<Workload> &workloads, const char *tag);
185 
186  /** Get CPU info.
187  *
188  * @return CPU info.
189  */
190  CPUInfo &cpu_info();
191  /** Get a hint for the best possible number of execution threads
192  *
193  * @warning In case we can't work out the best number of threads,
194  * std::thread::hardware_concurrency() is returned else 1 in case of bare metal builds
195  *
196  * @return Best possible number of execution threads to use
197  */
198  unsigned int num_threads_hint() const;
199 
200 protected:
201  /** Execute all the passed workloads
202  *
203  * @note there is no guarantee regarding the order in which the workloads will be executed or whether or not they will be executed in parallel.
204  *
205  * @param[in] workloads Array of workloads to run
206  */
207  virtual void run_workloads(std::vector<Workload> &workloads) = 0;
208 
209  /** Common scheduler logic to execute the given kernel
210  *
211  * @param[in] kernel Kernel to execute.
212  * @param[in] hints Hints for the scheduler.
213  * @param[in] window Window to use for kernel execution.
214  * @param[in] tensors Vector containing the tensors to operate on.
215  */
216  void schedule_common(ICPPKernel *kernel, const Hints &hints, const Window &window, ITensorPack &tensors);
217 
218 private:
219  unsigned int _num_threads_hint = {};
220 };
221 } // namespace arm_compute
222 #endif /* ARM_COMPUTE_ISCHEDULER_H */
std::function< void(const ThreadInfo &)> Workload
Signature for the workloads to execute.
Definition: IScheduler.h:135
IScheduler()
Default constructor.
Definition: IScheduler.cpp:34
Common interface for all kernels implemented in C++.
Definition: ICPPKernel.h:38
virtual void set_num_threads(unsigned int num_threads)=0
Sets the number of threads the scheduler will use to run the kernels.
virtual void schedule_op(ICPPKernel *kernel, const Hints &hints, const Window &window, ITensorPack &tensors)=0
Runs the kernel in the same thread as the caller synchronously.
Scheduler interface to run kernels.
Definition: IScheduler.h:41
Split the workload evenly among the threads.
static constexpr unsigned int split_dimensions_all
When arm_compute::ISchedular::Hints::_split_dimension is initialized with this value then the schedul...
Definition: IScheduler.h:62
CPUInfo & cpu_info()
Get CPU info.
Definition: IScheduler.cpp:40
virtual void run_tagged_workloads(std::vector< Workload > &workloads, const char *tag)
Execute all the passed workloads.
Definition: IScheduler.cpp:168
int threshold() const
Return the granule capping threshold to be used by dynamic scheduling.
Definition: IScheduler.h:124
Copyright (c) 2017-2021 Arm Limited.
Hints(unsigned int split_dimension, StrategyHint strategy=StrategyHint::STATIC, int threshold=0)
Constructor.
Definition: IScheduler.h:77
Split the workload dynamically using a bucket system.
std::function< int(int, int)> BindFunc
Function to be used and map a given thread id to a logical core id.
Definition: IScheduler.h:56
virtual ~IScheduler()=default
Destructor.
StrategyHint strategy() const
Return the prefered strategy to use to split workload.
Definition: IScheduler.h:116
Hints & set_split_dimension(unsigned int split_dimension)
Set the split_dimension hint.
Definition: IScheduler.h:87
virtual void schedule(ICPPKernel *kernel, const Hints &hints)=0
Runs the kernel in the same thread as the caller synchronously.
unsigned int num_threads_hint() const
Get a hint for the best possible number of execution threads.
Definition: IScheduler.cpp:51
Tensor packing service.
Definition: ITensorPack.h:39
unsigned int split_dimension() const
Return the prefered split dimension.
Definition: IScheduler.h:96
virtual unsigned int num_threads() const =0
Returns the number of threads that the SingleThreadScheduler has in his pool.
virtual void set_num_threads_with_affinity(unsigned int num_threads, BindFunc func)
Sets the number of threads the scheduler will use to run the kernels but also using a binding functio...
Definition: IScheduler.cpp:45
Hints & set_strategy(StrategyHint strategy)
Set the strategy hint.
Definition: IScheduler.h:107
Describe a multidimensional execution window.
Definition: Window.h:39
StrategyHint
Strategies available to split a workload.
Definition: IScheduler.h:45