diff options
| -rw-r--r-- | py/runtime.h | 1 | ||||
| -rw-r--r-- | py/scheduler.c | 83 | ||||
| -rw-r--r-- | py/vm.c | 48 |
3 files changed, 68 insertions, 64 deletions
diff --git a/py/runtime.h b/py/runtime.h index 4393fbfa82..779b66f2bd 100644 --- a/py/runtime.h +++ b/py/runtime.h @@ -76,7 +76,6 @@ void mp_deinit(void); void mp_sched_exception(mp_obj_t exc); void mp_sched_keyboard_interrupt(void); void mp_handle_pending(bool raise_exc); -void mp_handle_pending_tail(mp_uint_t atomic_state); #if MICROPY_ENABLE_SCHEDULER void mp_sched_lock(void); diff --git a/py/scheduler.c b/py/scheduler.c index 3966da2975..e8ad4e4f17 100644 --- a/py/scheduler.c +++ b/py/scheduler.c @@ -32,7 +32,11 @@ // sources such as interrupts and UNIX signal handlers). void MICROPY_WRAP_MP_SCHED_EXCEPTION(mp_sched_exception)(mp_obj_t exc) { MP_STATE_MAIN_THREAD(mp_pending_exception) = exc; - #if MICROPY_ENABLE_SCHEDULER + + #if MICROPY_ENABLE_SCHEDULER && !MICROPY_PY_THREAD + // Optimisation for the case where we have scheduler but no threading. + // Allows the VM to do a single check to exclude both pending exception + // and queued tasks. if (MP_STATE_VM(sched_state) == MP_SCHED_IDLE) { MP_STATE_VM(sched_state) = MP_SCHED_PENDING; } @@ -62,33 +66,17 @@ static inline bool mp_sched_empty(void) { return mp_sched_num_pending() == 0; } -// A variant of this is inlined in the VM at the pending exception check -void mp_handle_pending(bool raise_exc) { - if (MP_STATE_VM(sched_state) == MP_SCHED_PENDING) { - mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION(); - // Re-check state is still pending now that we're in the atomic section. - if (MP_STATE_VM(sched_state) == MP_SCHED_PENDING) { - mp_obj_t obj = MP_STATE_THREAD(mp_pending_exception); - if (obj != MP_OBJ_NULL) { - MP_STATE_THREAD(mp_pending_exception) = MP_OBJ_NULL; - if (!mp_sched_num_pending()) { - MP_STATE_VM(sched_state) = MP_SCHED_IDLE; - } - if (raise_exc) { - MICROPY_END_ATOMIC_SECTION(atomic_state); - nlr_raise(obj); - } - } - mp_handle_pending_tail(atomic_state); - } else { - MICROPY_END_ATOMIC_SECTION(atomic_state); - } +static inline void mp_sched_run_pending(void) { + mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION(); + if (MP_STATE_VM(sched_state) != MP_SCHED_PENDING) { + // Something else (e.g. hard IRQ) locked the scheduler while we + // acquired the lock. + MICROPY_END_ATOMIC_SECTION(atomic_state); + return; } -} -// This function should only be called by mp_handle_pending, -// or by the VM's inlined version of that function. -void mp_handle_pending_tail(mp_uint_t atomic_state) { + // Equivalent to mp_sched_lock(), but we're already in the atomic + // section and know that we're pending. MP_STATE_VM(sched_state) = MP_SCHED_LOCKED; #if MICROPY_SCHEDULER_STATIC_NODES @@ -118,14 +106,21 @@ void mp_handle_pending_tail(mp_uint_t atomic_state) { MICROPY_END_ATOMIC_SECTION(atomic_state); } + // Restore MP_STATE_VM(sched_state) to idle (or pending if there are still + // tasks in the queue). mp_sched_unlock(); } +// Locking the scheduler prevents tasks from executing (does not prevent new +// tasks from being added). We lock the scheduler while executing scheduled +// tasks and also in hard interrupts or GC finalisers. void mp_sched_lock(void) { mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION(); if (MP_STATE_VM(sched_state) < 0) { + // Already locked, increment lock (recursive lock). --MP_STATE_VM(sched_state); } else { + // Pending or idle. MP_STATE_VM(sched_state) = MP_SCHED_LOCKED; } MICROPY_END_ATOMIC_SECTION(atomic_state); @@ -135,12 +130,17 @@ void mp_sched_unlock(void) { mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION(); assert(MP_STATE_VM(sched_state) < 0); if (++MP_STATE_VM(sched_state) == 0) { - // vm became unlocked - if (MP_STATE_THREAD(mp_pending_exception) != MP_OBJ_NULL + // Scheduler became unlocked. Check if there are still tasks in the + // queue and set sched_state accordingly. + if ( + #if !MICROPY_PY_THREAD + // See optimisation in mp_sched_exception. + MP_STATE_THREAD(mp_pending_exception) != MP_OBJ_NULL || + #endif #if MICROPY_SCHEDULER_STATIC_NODES - || MP_STATE_VM(sched_head) != NULL + MP_STATE_VM(sched_head) != NULL || #endif - || mp_sched_num_pending()) { + mp_sched_num_pending()) { MP_STATE_VM(sched_state) = MP_SCHED_PENDING; } else { MP_STATE_VM(sched_state) = MP_SCHED_IDLE; @@ -196,17 +196,26 @@ bool mp_sched_schedule_node(mp_sched_node_t *node, mp_sched_callback_t callback) } #endif -#else // MICROPY_ENABLE_SCHEDULER +#endif // MICROPY_ENABLE_SCHEDULER -// A variant of this is inlined in the VM at the pending exception check +// Called periodically from the VM or from "waiting" code (e.g. sleep) to +// process background tasks and pending exceptions (e.g. KeyboardInterrupt). void mp_handle_pending(bool raise_exc) { if (MP_STATE_THREAD(mp_pending_exception) != MP_OBJ_NULL) { + mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION(); mp_obj_t obj = MP_STATE_THREAD(mp_pending_exception); - MP_STATE_THREAD(mp_pending_exception) = MP_OBJ_NULL; - if (raise_exc) { - nlr_raise(obj); + if (obj != MP_OBJ_NULL) { + MP_STATE_THREAD(mp_pending_exception) = MP_OBJ_NULL; + if (raise_exc) { + MICROPY_END_ATOMIC_SECTION(atomic_state); + nlr_raise(obj); + } } + MICROPY_END_ATOMIC_SECTION(atomic_state); } + #if MICROPY_ENABLE_SCHEDULER + if (MP_STATE_VM(sched_state) == MP_SCHED_PENDING) { + mp_sched_run_pending(); + } + #endif } - -#endif // MICROPY_ENABLE_SCHEDULER @@ -1295,41 +1295,37 @@ yield: #endif pending_exception_check: + // We've just done a branch, use this as a convenient point to + // run periodic code/checks and/or bounce the GIL.. i.e. + // not _every_ instruction but on average a branch should + // occur every few instructions. MICROPY_VM_HOOK_LOOP + // Check for pending exceptions or scheduled tasks to run. + // Note: it's safe to just call mp_handle_pending(true), but + // we can inline the check for the common case where there is + // neither. + if ( #if MICROPY_ENABLE_SCHEDULER - // This is an inlined variant of mp_handle_pending - if (MP_STATE_VM(sched_state) == MP_SCHED_PENDING) { - mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION(); - // Re-check state is still pending now that we're in the atomic section. - if (MP_STATE_VM(sched_state) == MP_SCHED_PENDING) { - MARK_EXC_IP_SELECTIVE(); - mp_obj_t obj = MP_STATE_THREAD(mp_pending_exception); - if (obj != MP_OBJ_NULL) { - MP_STATE_THREAD(mp_pending_exception) = MP_OBJ_NULL; - if (!mp_sched_num_pending()) { - MP_STATE_VM(sched_state) = MP_SCHED_IDLE; - } - MICROPY_END_ATOMIC_SECTION(atomic_state); - RAISE(obj); - } - mp_handle_pending_tail(atomic_state); - } else { - MICROPY_END_ATOMIC_SECTION(atomic_state); - } - } + #if MICROPY_PY_THREAD + // Scheduler + threading: Scheduler and pending exceptions are independent, check both. + MP_STATE_VM(sched_state) == MP_SCHED_PENDING || MP_STATE_THREAD(mp_pending_exception) != MP_OBJ_NULL #else - // This is an inlined variant of mp_handle_pending - if (MP_STATE_THREAD(mp_pending_exception) != MP_OBJ_NULL) { + // Scheduler + non-threading: Optimisation: pending exception sets sched_state, only check sched_state. + MP_STATE_VM(sched_state) == MP_SCHED_PENDING + #endif + #else + // No scheduler: Just check pending exception. + MP_STATE_THREAD(mp_pending_exception) != MP_OBJ_NULL + #endif + ) { MARK_EXC_IP_SELECTIVE(); - mp_obj_t obj = MP_STATE_THREAD(mp_pending_exception); - MP_STATE_THREAD(mp_pending_exception) = MP_OBJ_NULL; - RAISE(obj); + mp_handle_pending(true); } - #endif #if MICROPY_PY_THREAD_GIL #if MICROPY_PY_THREAD_GIL_VM_DIVISOR + // Don't bounce the GIL too frequently (default every 32 branches). if (--gil_divisor == 0) #endif { |