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rahuljn

Process Synchronisation issue

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Hello experts

 

I have a tricky synchronisation to achieve in one model. Here I have two thread processes, The IInd one is waiting for an event which is notified by Ist thread. Here after the event notification from Ist process, I wait for one delta cycle to allow IInd one to come out of wait and do some stuff before Ist one proceed. But what I am abserving that after the wait in Ist process, in next delta cycle both process becomes ready to run and scheduler may pick them in any order but I want IInd process  to run before Ist one. I may use another wait but is there any another way to achieve this ?

 

Here is one simple examle to show this issue

 

In the below example, I am getting the following output

P3

P6

I am expecting

P3

P6

 

#include "systemc.h"

SC_MODULE(event_trial){
    public:
    sc_event se;
    SC_CTOR(event_trial) {
 SC_THREAD(process1);
 SC_THREAD(process2);
    }

    void process1(){
 wait(SC_ZERO_TIME);
 se.notify(SC_ZERO_TIME);
 wait(SC_ZERO_TIME);
 cout<<"P3"<<endl;
    }

    void process2(){
 wait(se);
 cout<<"P6"<<endl;
    }
};

int sc_main(int , char**){
    event_trial et("et");
    sc_start();
    return 0;
}

 

Can anyone suggest a recommended way to achieve the desired output

 

Thanks

Rahul

 

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Hello experts

 

I have a tricky synchronisation to achieve in one model. Here I have two thread processes, The IInd one is waiting for an event which is notified by Ist thread. Here after the event notification from Ist process, I wait for one delta cycle to allow IInd one to come out of wait and do some stuff before Ist one proceed. But what I am abserving that after the wait in Ist process, in next delta cycle both process becomes ready to run and scheduler may pick them in any order but I want IInd process  to run before Ist one. I may use another wait but is there any another way to achieve this ?

 

Here is one simple examle to show this issue

 

In the below example, I am getting the following output

P3

P6

I am expecting

P3

P6

 

#include "systemc.h"

SC_MODULE(event_trial){

    public:

    sc_event se;

    SC_CTOR(event_trial) {

 SC_THREAD(process1);

 SC_THREAD(process2);

    }

    void process1(){

 wait(SC_ZERO_TIME);

 se.notify(SC_ZERO_TIME);

 wait(SC_ZERO_TIME);

 cout<<"P3"<<endl;

    }

    void process2(){

 wait(se);

 cout<<"P6"<<endl;

    }

};

int sc_main(int , char**){

    event_trial et("et");

    sc_start();

    return 0;

}

 

Can anyone suggest a recommended way to achieve the desired output

 

Thanks

Rahul

Hello Sir,

Please look up the built-in SystemC classes sc_mutex, sc_semaphore,

and use them. These are designed for process synchronization and so

why re-invent the wheel ? Hope that helps.

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sc_event's are the way to guarantee ordering in SystemC. Most channels use events to establish ordering. One or more processes wait on an sc_event, while another generates the sc_event. If you want to guarantee ordering, use events. If you look under the hood of a sc_mutex, sc_semaphore, sc_signal, sc_fifo, or any other properly designed channel, you will find events and flags.

class Top_module {
  sc_event evt1, evt2;
  void thread1(void);
  void thread2(void);
  SC_CTOR(Top_module);
};

Top_module::Top_module(sc_module_name nm) {
  SC_HAS_PROCESS(Top_module);
  SC_THREAD(thread1);
  SC_THREAD(thread2);
}

void Top_module::thread1(void) {
  for(; {
     evt1.notify(SC_ZERO_TIME);
     wait(evt2);
     cout << "Got evt2" << endl;
  }
}

void Top_module::thread2(void) {
  for (int i=0; i!=10; ++i) {
    wait(evt1);
    cout << "Got evt1" << endl;
    evt2.notify(SC_ZERO_TIME);
  }
  sc_stop();
}

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