jingfei195887 opened a new pull request, #20652:
URL: https://github.com/apache/nuttx/pull/20652
## Summary
Two more footprint changes related to #20414 (follow-up to #20628). Both keep
behavior unchanged and only drop flash.
1. **sched/wqueue: move `g_hpwork`/`g_lpwork` to `.bss`**
The static initializers put both kernel work queues in `.data`, so their
initial image is stored in flash. Only the two self-referencing list heads
and the thread count are non-zero; the semaphores, spinlock and timer were
already zero-initialized. The queues now live in `.bss`, and
`work_initialize()` sets those three fields at the start of `nx_start()`,
before anything can queue work.
2. **sched/spawn: skip policy handling on FIFO-only builds**
With `CONFIG_RR_INTERVAL=0` and no `CONFIG_SCHED_SPORADIC`, `SCHED_FIFO`
is
the only scheduling policy and every task already uses it, yet
`posix_spawnattr_init()` queries the caller's policy and
`spawn_execattrs()`
calls `nxsched_set_scheduler()`, which keeps the policy-switching code
linked. In that configuration the spawn policy now defaults to
`SCHED_FIFO`
and only the priority is applied. Other policies are still rejected with
`-EINVAL`, as before.
## Impact
- (1) applies to every build with `CONFIG_SCHED_WORKQUEUE`. 120 bytes per
queue
move from `.data` to `.bss`, so total RAM is unchanged.
- (2) applies only to FIFO-only builds (`RR_INTERVAL=0`, no sporadic, 280
in-tree defconfigs). Builds with round-robin or sporadic scheduling are
unchanged.
- No API or ABI change. Make and CMake are unaffected (no new sources).
## Testing
Host: Ubuntu x86_64, arm-none-eabi-gcc 10.3.1 20210621. Clean CMake builds of
`stm32f103-minimum:nsh` on master f6e5be7972. Flash = text + data.
| configuration | master | this PR | delta |
|---|---:|---:|---:|
| defconfig (text/data/bss) | 51975 / 468 / 2952 | 52007 / 348 / 3072 |
flash **-88** |
| `+SCHED_LPWORK` (flash) | 52611 | 52419 | **-192** |
| `RR_INTERVAL=0` (flash, on top of commit 1) | 52123 | 51947 | **-176** |
| defconfig, commit 2 only effect | 52355 | 52355 | 0 |
With `RR_INTERVAL=0`, `nxsched_set_scheduler`, `nxsched_get_scheduler` and
`sched_getscheduler` are no longer linked; with `RR_INTERVAL=0` plus
`SCHED_SPORADIC=y` they are still linked and the build is unchanged.
Other checks:
- Builds: `sim:nsh` (RR_INTERVAL=0), `sim:ostest`, `sim:smp`, and
`stm32f103-minimum:nsh` with `RR_INTERVAL=0 SCHED_SPORADIC=y`.
- `sim:smp` boots to `nsh>`.
- `sim:nsh` with `RR_INTERVAL=0`: `hello` runs and `ps` shows the same
policy (FIFO) and priorities as master.
- `sim:ostest` (with and without `RR_INTERVAL=0`): runs reached `wqueue_test`
in a 300 s timeout with no `ERROR`, assertion or panic, same test order as
master. ostest did not finish within the timeout in either build, so this
shows no difference rather than a full pass.
- `./tools/checkpatch.sh -g master..HEAD`: all checks pass.
Not tested on hardware.
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