src/cpu/testers/traffic_gen/traffic_gen.hh

   1 /*
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  37
  38 #ifndef __CPU_TRAFFIC_GEN_TRAFFIC_GEN_HH__
  39 #define __CPU_TRAFFIC_GEN_TRAFFIC_GEN_HH__
  40
  41 #include <unordered_map>
  42
  43 #include "cpu/testers/traffic_gen/base.hh"
  44
  45 struct TrafficGenParams;
  46
  47 /**
  48  * The traffic generator is a module that generates stimuli for
  49  * the memory system, based on a collection of simple behaviours that
  50  * are either probabilistic or based on traces. It can be used stand
  51  * alone for creating test cases for interconnect and memory
  52  * controllers, or function as a black-box replacement for system
  53  * components that are not yet modelled in detail, e.g. a video engine
  54  * or baseband subsystem in an SoC.
  55  *
  56  * The traffic generator has a single request port that is used to send
  57  * requests, independent of the specific behaviour. The behaviour of
  58  * the traffic generator is specified in a configuration file, and this
  59  * file describes a state transition graph where each state is a
  60  * specific generator behaviour. Examples include idling, generating
  61  * linear address sequences, random sequences and replay of captured
  62  * traces. By describing these behaviours as states, it is straight
  63  * forward to create very complex behaviours, simply by arranging them
  64  * in graphs. The graph transitions can also be annotated with
  65  * probabilities, effectively making it a Markov Chain.
  66  */
  67 class TrafficGen : public BaseTrafficGen
  68 {
  69   private: // Params
  70     /**
  71      * The config file to parse.
  72      */
  73     const std::string configFile;
  74
  75   private:
  76     /**
  77      * Resolve a file path in the configuration file.
  78      *
  79      * This method resolves a relative path to a file that has been
  80      * referenced in the configuration file. It first tries to resolve
  81      * the file relative to the configuration file's path. If that
  82      * fails, it falls back to constructing a path relative to the
  83      * current working directory.
  84      *
  85      * Absolute paths are returned unmodified.
  86      *
  87      * @param name Path to resolve
  88      */
  89     std::string resolveFile(const std::string &name);
  90
  91      /**
  92       * Parse the config file and build the state map and
  93       * transition matrix.
  94       */
  95     void parseConfig();
  96
  97     /**
  98      * Use the transition matrix to find the next state index.
  99      */
 100     size_t nextState();
 101
 102     /** Struct to represent a probabilistic transition during parsing. */
 103     struct Transition {
 104         uint32_t from;
 105         uint32_t to;
 106         double p;
 107     };
 108
 109     /** State transition matrix */
 110     std::vector<std::vector<double> > transitionMatrix;
 111
 112     /** Index of the current state */
 113     uint32_t currState;
 114
 115     /** Map of generator states */
 116     std::unordered_map<uint32_t, std::shared_ptr<BaseGen>> states;
 117
 118   protected: // BaseTrafficGen
 119     std::shared_ptr<BaseGen> nextGenerator() override;
 120
 121   public:
 122
 123     TrafficGen(const TrafficGenParams* p);
 124
 125     ~TrafficGen() {}
 126
 127     void init() override;
 128     void initState() override;
 129
 130     void serialize(CheckpointOut &cp) const override;
 131     void unserialize(CheckpointIn &cp) override;
 132
 133 };
 134
 135 #endif //__CPU_TRAFFIC_GEN_TRAFFIC_GEN_HH__