Confusion with disable fork?

SystemVerilog
, , ,
1 
class fork_join_task; 
  task fork_join_wait(int random_time);
    fork: fork_1
      begin
       #random_time;
       $display("process1 %t",$time);
      end
      begin
        #20;
        $error("Process 1 not completed at %t",$time);
       end
    join_any
    disable fork_1; //giving label name,kill all process for wenever you call and different time to call
  endtask
endclass

module fork_join;
  fork_join_task c1,c2;
  initial begin
    c1=new();
    c2=new();
    fork
      c1.fork_join_wait(10);
      c2.fork_join_wait(30);
    join
 //   #200;
    $display($stime,"\t out side the fork");
 //   $finish;
  end

endmodule

and I got output

process1 10

10 out side the fork

why can’t I use disable<label_name> instead of disable fork in this code?

2

In reply to Lokesh402:
Your disable fork_1; occurs after the join_any. There is nothing to disable.
See my updated model


    
    fork: fork_1
      begin
       #random_time;
       $display("process1 %t",$time);
      end
      begin
        #20;
        $error("Process 1 not completed at %t",$time);
       end

       begin #5 $display("after the #40"); end 

       begin #2 $display($stime,"\t inside the fork");
             disable fork_1; 
       end 
    // join_any
    join: fork_1
    // disable fork_1; // 
      // fork_1; //giving label name,kill all process for wenever you call and different time to call
  endtask
Sim results
# KERNEL:          2	 inside the fork
# KERNEL:          2	 out side the fork

Ben Cohen
http://www.systemverilog.us/ ben@systemverilog.us
For training, consulting, services: contact http://cvcblr.com/home.html
** SVA Handbook 4th Edition, 2016 ISBN 978-1518681448
…

  1. SVA Package: Dynamic and range delays and repeats SVA: Package for dynamic and range delays and repeats - SystemVerilog - Verification Academy
  2. Free books: Component Design by Example https://rb.gy/9tcbhl
    Real Chip Design and Verification Using Verilog and VHDL($3) https://rb.gy/cwy7nb
  3. Papers:
3

In reply to Lokesh402:

It might have helped to explain the results you were expecting versus what you actually see.

disable label; kills any process executing under that label name. At the point you execute the first disable fork_1;, there are 3 active processes to be disabled, and the second disable fork_1 executes with nothing to disable.

disable fork; only kills the children of the process executing the disable command. So if you change to adisable fork; only 1 process forked by the c2.fork_join_wait(10) gets killed. The other process forked by the c1.fork_join_wait(30) will get to the #20 $error message.

4

In reply to dave_59:

Hi Dev,
Sorry i asked wrong way, actual doubt is
I have two objects(c1,c2) and one of object(c1) is called disable fork_1(label),but it’s disable fork join_any(fork_1) in all objects. why it’s disabled all the objects(disable fork_1 in c2)?

5

In reply to Lokesh402:

From LRM::

9.6.3 Disable fork statement

The disable construct terminates a process when applied to the named block or statement being executed by the process. The disable fork statement differs from disable in that disable fork considers the dynamic parent-child relationship of the processes, whereas disable uses the static, syntactical information of the disabled block. Thus, disable shall end all processes executing a particular block, whether the processes were forked by the calling thread or not, while disable fork shall end only the processes that were spawned by the calling thread.