Db Resource Management : grp1 vs grp2 (80% cpu vs 20% cpu)

Hello,

I have created 2 consumers groups :

grp1 => 80% cpu associated to user_1

grp2 => 20 % cpu  associated to user_2

i make 2 connections to myDB (user_1 & user_2) and i query the db with the same sql_id:

DECLARE
    sqrtval NUMBER := 0;
BEGIN
    FOR idx1 IN 1..2000
        LOOP
            FOR idx2 IN 1..1000
                LOOP
                    SELECT (SQRT(idx2/idx1)) INTO sqrtval FROM DUAL;
                END LOOP;
        END LOOP;
END;
/

Remark : The 2 queries complete at teh same time

Question: The user_1 should have complete before the user_2 ? shouldn't he ?

Where can i see that user_1 has used 80% of cpu & user_2 only 20 % ?

thanks

Of course :

1) the plan is active (v$rsrc_plan).

2) user are set in their respective groups (exec DBMS_RESOURCE_MANAGER.SWITCH_CONSUMER_GROUP_FOR_USER).