offcputime did not get "D" state process

Hi,
I run 200 below program on my pc or orin-x:
```
#include
#include

int main() {
vfork();
sleep(100);
return 0;
}
```
The cpu load average can be pulled to 200.
And meanwhile, I use offcputime to monitor the system's D state, but I got nothing about the program.
Please help me. Thanks a lot.