For loop increments at 0 simulation time

SystemVerilog
, , ,
1 
class forever_ex;
	int dt2, dt3;

	task forever_lp_check();
		forever begin
			$display("Inside forever loop: erealtime = %0t, time = %0t", $realtime, $time);
			@(dt2) 
			$display("dt2=%d", dt2);
			dt3 = dt2;
			$display(dt2, dt3);
		end
	endtask

	task incr_dt2();
		for(int ii=0; ii<10; ii++) begin
			//#1ns;
			dt2 +=10;
			$display("Inside dt2 incr : realtime = %0t, time = %0t", $realtime, $time);
			$display(dt2);
		end
	endtask
endclass

module top();

	initial begin
		forever_ex forever_ex_ii;
		forever_ex_ii = new();

		fork
			$display("Before forever loop call: realtime = %0t, time = %0t", $realtime, $time);
			forever_ex_ii.forever_lp_check();
		join_none 

		$display("Before d2 incr call: realtime = %0t, time = %0t", $realtime, $time);
		forever_ex_ii.incr_dt2();
		$display("here1");


	end
endmodule

Result:

Before d2 incr call: realtime = 0, time = 0
Inside dt2 incr : realtime = 0, time = 0
         10
Inside dt2 incr : realtime = 0, time = 0
         20
Inside dt2 incr : realtime = 0, time = 0
         30
Inside dt2 incr : realtime = 0, time = 0
         40
Inside dt2 incr : realtime = 0, time = 0
         50
Inside dt2 incr : realtime = 0, time = 0
         60
Inside dt2 incr : realtime = 0, time = 0
         70
Inside dt2 incr : realtime = 0, time = 0
         80
Inside dt2 incr : realtime = 0, time = 0
         90
Inside dt2 incr : realtime = 0, time = 0
        100
here1
Before forever loop call: realtime = 0, time = 0
Inside forever loop: erealtime = 0, time = 0

Question:
Although I understand the execution of the forever_lp_check() task call within fork-join_none can be random - either before or after incr_dt2() is executed, what I cannot understand is how can for loop increment at 0 realtime as well as sim time. Could you please help explaining.

2

In reply to natasv:

There are no delays in this code (other than in the comments), so how can time advance beyond 0. Maybe you should clarify what you were expecting to see.

3

I was expecting to see the addition operation to consume some real time.
When I uncommented the #1ns, I saw what I wanted. But then an addition operation counting upto 100 should consume some time in reality, I thought

4

In reply to natasv:

$realtime returns current time step expressed as a real number in the timescale of the current scope, not the elapsed CPU time it takes to execute the simulation.