# What are the insert and remove indexes in the thread queue structure?



## Stefan Andritoiu (Jun 7, 2015)

In the thread queue structure in sched_ule.c, what do these 2 fields represent exactly?

```
struct tdq {
   ...
   u_char tdq_idx; /* Current insert index. */
   u_char tdq_ridx; /* Current removal index. */
   ...
}
```


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