A common question in interviews for System Verilog is ....
How do you come out of fork-join_none/any if 2 out of the 3 process in fork are complete.
Fork-join_any will wait until any one process is complete.
If you want to wait until any two process are complete, you can use semaphores or static variables inside each process and wait on the semaphore/variable for join_any/join_none statement.
One more questions revolving it is with fork_join.
You have 3 processes, and you need to come out of fork_join when 2 out of 3 process are complete.
How to achieve this?
One way of doing it is using labels.
Check out....
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 | class test; static int cnt; task check_fork; fork begin: p1 #30;cnt++; $display("%t - Process-1 cnt:%d",$time,cnt); if(cnt==2) begin disable p3; disable p2; end end begin: p2 #40;cnt++; $display("%t - Process-2 cnt:%d",$time,cnt); if(cnt==2) begin disable p3; disable p1; end end begin: p3 #10;cnt++; $display("%t - Process-3 cnt:%d",$time,cnt); if(cnt==2) begin disable p2; disable p1; end end join $display("%t - Process-Complete cnt:%d",$time,cnt); endtask endclass: test module top; test s; initial begin s=new; s.check_fork; end endmodule: top |
RESULT:
Chronologic VCS simulator copyright 1991-2021
Contains Synopsys proprietary information.
Compiler version S-2021.09; Runtime version S-2021.09; Apr 20 11:06 2023
10 - Process-3 cnt: 1
30 - Process-1 cnt: 2
30 - Process-Complete cnt: 2
V C S S i m u l a t i o n R e p o r t
Time: 30 ns
CPU Time: 0.560 seconds; Data structure size: 0.0Mb
Thu Apr 20 11:06:20 2023