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Tiago Medicci Serrano
50aeea2dc0
- `g_iob_sem.semcount` must be equal to the total number of free IOBs. It can also be negative if there are no free IOBs and there are threads waiting for an IOB. - g_throttle_sem.semcount represents the number of IOBs available for throttled IOB allocations. Like any other semaphore, it should only go negative if there is a thread waiting for it. - Both semaphores are related to the same resource (free IOBs), hence, they must be incremented/decremented simultaneously: - Whenever a IOB buffer is freed, if a thread is waiting for a non-throttled IOB or a thread is waiting for a throttled IOB and we have at least `CONFIG_IOB_THROTTLE` buffers available, the IOB is put in the committed list (`g_iob_committed`). Otherwise, it is put in the common free list (`g_iob_freelist`). - `g_iob_sem` is always incremented when an IOB buffer is freed, but `g_throttle_sem` is incremented only if we have at least CONFIG_IOB_THROTTLE buffers free. - Both semaphores are posted with the schedule locked to avoid any mismatches in the semaphores count. - If a task is waiting for an IOB semaphore (`iob_allocwait`) is awakened and would check the `g_iob_committed`. The highest priority task waiting for a semaphore will be awakened first.