What does QNX's top CPU idle percentage really means?

I am using QNX (ARM Cortex A53 with FOUR cores) and when I do ***top***, I have the below. According to the below idle percentages for each of the core, I'd like to confirm CPU/Core 0 is the most idle, that is, being used only ~7%, thus being the most candidate available for usage? CPU 1 is maxed out with zero percentage of idling. The one process uses most of one of the core is my_app, which has four thread. Based idle CPU idle percentage info below, it looks like my_app is tied to Core 2. But why is Core 1 has 0% of idling, that is, maxed out of percentage of usage. Thanks for any explanation.

PID         TID PRI STATE    HH:MM:SS    CPU     COMMAND
1335344     9   254 Run      0:32:31     25.00%  my_app
1335344     5   253 Run      0:06:58     5.60%   my_app
1335344     7   253 Rdy      0:00:38     0.51%   my_app
1335344     6   253 Rdy      0:00:32     0.43%   my_app

              Min        Max       Average 
CPU 0 idle:   93%        93%        93% 
CPU 1 idle:    0%         0%         0% 
CPU 2 idle:   72%        73%        72% 
CPU 3 idle:   93%        94%        93%
 
Mem Avail:   1396MB      1396MB      1396MB  
Processes:    55         55         55    
Threads:     142        142        142