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. |
||
|---|---|---|
| .github | ||
| arch | ||
| audio | ||
| binfmt | ||
| boards | ||
| cmake | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| dummy | ||
| fs | ||
| graphics | ||
| include | ||
| libs | ||
| mm | ||
| net | ||
| openamp | ||
| pass1 | ||
| sched | ||
| syscall | ||
| tools | ||
| video | ||
| wireless | ||
| .asf.yaml | ||
| .gitignore | ||
| .yamllint | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
| Kconfig | ||
| LICENSE | ||
| Makefile | ||
| NOTICE | ||
| README.md | ||
| ReleaseNotes | ||
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
Getting Started
First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.
Documentation
You can find the current NuttX documentation on the Documentation Page.
Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.
The old NuttX documentation is still available in the Apache wiki.
Supported Boards
NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.
Contributing
If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.
License
The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.