#include <kern/spl.h>
#include <kern/task.h>
#include <kern/thread.h>
+#include <kern/policy_internal.h>
+
#include <mach/policy.h>
#include <kern/syscall_subr.h>
#include <mach/mach_host_server.h>
#include <mach/mach_syscalls.h>
#include <sys/kdebug.h>
+#include <kern/ast.h>
#ifdef MACH_BSD
extern void workqueue_thread_yielded(void);
extern sched_call_t workqueue_get_sched_callback(void);
#endif /* MACH_BSD */
+extern wait_result_t thread_handoff_reason(thread_t thread, ast_t reason);
/* Called from commpage to take a delayed preemption when exiting
* the "Preemption Free Zone" (PFZ).
* swtch and swtch_pri both attempt to context switch (logic in
* thread_block no-ops the context switch if nothing would happen).
* A boolean is returned that indicates whether there is anything
- * else runnable.
- *
- * This boolean can be used by a thread waiting on a
- * lock or condition: If FALSE is returned, the thread is justified
- * in becoming a resource hog by continuing to spin because there's
- * nothing else useful that the processor could do. If TRUE is
- * returned, the thread should make one more check on the
- * lock and then be a good citizen and really suspend.
+ * else runnable. That's no excuse to spin, though.
*/
static void
swtch_continue(void)
{
- register processor_t myprocessor;
- boolean_t result;
+ processor_t myprocessor;
+ boolean_t result;
- disable_preemption();
+ disable_preemption();
myprocessor = current_processor();
- result = !SCHED(processor_queue_empty)(myprocessor) || rt_runq.count > 0;
+ result = SCHED(thread_should_yield)(myprocessor, current_thread());
enable_preemption();
thread_syscall_return(result);
swtch(
__unused struct swtch_args *args)
{
- register processor_t myprocessor;
+ processor_t myprocessor;
boolean_t result;
disable_preemption();
myprocessor = current_processor();
- if (SCHED(processor_queue_empty)(myprocessor) && rt_runq.count == 0) {
+ if (!SCHED(thread_should_yield)(myprocessor, current_thread())) {
mp_enable_preemption();
return (FALSE);
disable_preemption();
myprocessor = current_processor();
- result = !SCHED(processor_queue_empty)(myprocessor) || rt_runq.count > 0;
+ result = SCHED(thread_should_yield)(myprocessor, current_thread());
enable_preemption();
return (result);
static void
swtch_pri_continue(void)
{
- register processor_t myprocessor;
- boolean_t result;
+ processor_t myprocessor;
+ boolean_t result;
thread_depress_abort_internal(current_thread());
- disable_preemption();
+ disable_preemption();
myprocessor = current_processor();
- result = !SCHED(processor_queue_empty)(myprocessor) || rt_runq.count > 0;
+ result = SCHED(thread_should_yield)(myprocessor, current_thread());
mp_enable_preemption();
thread_syscall_return(result);
swtch_pri(
__unused struct swtch_pri_args *args)
{
- register processor_t myprocessor;
+ processor_t myprocessor;
boolean_t result;
disable_preemption();
myprocessor = current_processor();
- if (SCHED(processor_queue_empty)(myprocessor) && rt_runq.count == 0) {
+ if (!SCHED(thread_should_yield)(myprocessor, current_thread())) {
mp_enable_preemption();
return (FALSE);
disable_preemption();
myprocessor = current_processor();
- result = !SCHED(processor_queue_empty)(myprocessor) || rt_runq.count > 0;
+ result = SCHED(thread_should_yield)(myprocessor, current_thread());
enable_preemption();
return (result);
}
-static int
+static boolean_t
thread_switch_disable_workqueue_sched_callback(void)
{
sched_call_t callback = workqueue_get_sched_callback();
- thread_t self = current_thread();
- if (!callback || self->sched_call != callback) {
- return FALSE;
- }
- spl_t s = splsched();
- thread_lock(self);
- thread_sched_call(self, NULL);
- thread_unlock(self);
- splx(s);
- return TRUE;
+ return thread_disable_sched_call(current_thread(), callback) != NULL;
}
static void
thread_switch_enable_workqueue_sched_callback(void)
{
sched_call_t callback = workqueue_get_sched_callback();
- thread_t self = current_thread();
- spl_t s = splsched();
- thread_lock(self);
- thread_sched_call(self, callback);
- thread_unlock(self);
- splx(s);
+ thread_reenable_sched_call(current_thread(), callback);
}
static void
thread_switch_continue(void)
{
- register thread_t self = current_thread();
+ thread_t self = current_thread();
int option = self->saved.swtch.option;
boolean_t reenable_workq_callback = self->saved.swtch.reenable_workq_callback;
thread_switch(
struct thread_switch_args *args)
{
- register thread_t thread, self = current_thread();
+ thread_t thread = THREAD_NULL;
+ thread_t self = current_thread();
mach_port_name_t thread_name = args->thread_name;
int option = args->option;
mach_msg_timeout_t option_time = args->option_time;
/*
* Translate the port name if supplied.
*/
- if (thread_name != MACH_PORT_NULL) {
- ipc_port_t port;
+ if (thread_name != MACH_PORT_NULL) {
+ ipc_port_t port;
if (ipc_port_translate_send(self->task->itk_space,
- thread_name, &port) == KERN_SUCCESS) {
+ thread_name, &port) == KERN_SUCCESS) {
ip_reference(port);
ip_unlock(port);
ip_release(port);
if (thread == self) {
- (void)thread_deallocate_internal(thread);
+ thread_deallocate(thread);
thread = THREAD_NULL;
}
}
- else
- thread = THREAD_NULL;
}
- else
- thread = THREAD_NULL;
-
if (option == SWITCH_OPTION_OSLOCK_DEPRESS || option == SWITCH_OPTION_OSLOCK_WAIT) {
if (thread != THREAD_NULL) {
* a thread in another task)
*/
- (void)thread_deallocate_internal(thread);
+ thread_deallocate(thread);
thread = THREAD_NULL;
} else {
/*
* Attempt to kick the lock owner up to our same IO throttling tier.
* If the thread is currently blocked in throttle_lowpri_io(),
* it will immediately break out.
+ *
+ * TODO: SFI break out?
*/
int new_policy = proc_get_effective_thread_policy(self, TASK_POLICY_IO);
-
+
set_thread_iotier_override(thread, new_policy);
}
}
* Try to handoff if supplied.
*/
if (thread != THREAD_NULL) {
- processor_t processor;
- spl_t s;
+ spl_t s = splsched();
- s = splsched();
- thread_lock(thread);
+ /* This may return a different thread if the target is pushing on something */
+ thread_t pulled_thread = thread_run_queue_remove_for_handoff(thread);
KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED_THREAD_SWITCH)|DBG_FUNC_NONE,
- thread_tid(thread), thread->state, 0, 0, 0);
-
- /*
- * Check that the thread is not bound
- * to a different processor, and that realtime
- * is not involved.
- *
- * Next, pull it off its run queue. If it
- * doesn't come, it's not eligible.
- */
- processor = current_processor();
- if (processor->current_pri < BASEPRI_RTQUEUES &&
- thread->sched_pri < BASEPRI_RTQUEUES &&
- (thread->bound_processor == PROCESSOR_NULL ||
- thread->bound_processor == processor) &&
- thread_run_queue_remove(thread) ) {
- /*
- * Hah, got it!!
- */
- thread_unlock(thread);
-
- (void)thread_deallocate_internal(thread);
+ thread_tid(thread), thread->state,
+ pulled_thread ? TRUE : FALSE, 0, 0);
+
+ if (pulled_thread != THREAD_NULL) {
+ /* We can't be dropping the last ref here */
+ thread_deallocate_safe(thread);
if (wait_option)
assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE,
- option_time, scale_factor);
- else
- if (depress_option)
+ option_time, scale_factor);
+ else if (depress_option)
thread_depress_ms(option_time);
self->saved.swtch.option = option;
self->saved.swtch.reenable_workq_callback = reenable_workq_callback;
- thread_run(self, (thread_continue_t)thread_switch_continue, NULL, thread);
+ thread_run(self, (thread_continue_t)thread_switch_continue, NULL, pulled_thread);
/* NOTREACHED */
+ panic("returned from thread_run!");
}
- thread_unlock(thread);
splx(s);
thread_deallocate(thread);
}
-
+
if (wait_option)
assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE, option_time, scale_factor);
- else
- if (depress_option)
+ else if (depress_option)
thread_depress_ms(option_time);
-
+
self->saved.swtch.option = option;
self->saved.swtch.reenable_workq_callback = reenable_workq_callback;
return (KERN_SUCCESS);
}
+/* Returns a +1 thread reference */
+thread_t
+port_name_to_thread_for_ulock(mach_port_name_t thread_name)
+{
+ thread_t thread = THREAD_NULL;
+ thread_t self = current_thread();
+
+ /*
+ * Translate the port name if supplied.
+ */
+ if (thread_name != MACH_PORT_NULL) {
+ ipc_port_t port;
+
+ if (ipc_port_translate_send(self->task->itk_space,
+ thread_name, &port) == KERN_SUCCESS) {
+ ip_reference(port);
+ ip_unlock(port);
+
+ thread = convert_port_to_thread(port);
+ ip_release(port);
+
+ if (thread == THREAD_NULL) {
+ return thread;
+ }
+
+ if ((thread == self) || (thread->task != self->task)) {
+ thread_deallocate(thread);
+ thread = THREAD_NULL;
+ }
+ }
+ }
+
+ return thread;
+}
+
+/* This function is called after an assert_wait(), therefore it must not
+ * cause another wait until after the thread_run() or thread_block()
+ *
+ * Consumes a ref on thread
+ */
+wait_result_t
+thread_handoff(thread_t thread)
+{
+ thread_t deallocate_thread = THREAD_NULL;
+ thread_t self = current_thread();
+
+ /*
+ * Try to handoff if supplied.
+ */
+ if (thread != THREAD_NULL) {
+ spl_t s = splsched();
+
+ thread_t pulled_thread = thread_run_queue_remove_for_handoff(thread);
+
+ KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED_THREAD_SWITCH)|DBG_FUNC_NONE,
+ thread_tid(thread), thread->state,
+ pulled_thread ? TRUE : FALSE, 0, 0);
+
+ if (pulled_thread != THREAD_NULL) {
+ /* We can't be dropping the last ref here */
+ thread_deallocate_safe(thread);
+
+ int result = thread_run(self, THREAD_CONTINUE_NULL, NULL, pulled_thread);
+
+ splx(s);
+ return result;
+ }
+
+ splx(s);
+
+ deallocate_thread = thread;
+ thread = THREAD_NULL;
+ }
+
+ int result = thread_block(THREAD_CONTINUE_NULL);
+ if (deallocate_thread != THREAD_NULL) {
+ thread_deallocate(deallocate_thread);
+ }
+
+ return result;
+}
+
/*
* Depress thread's priority to lowest possible for the specified interval,
* with a value of zero resulting in no timeout being scheduled.
thread_depress_abstime(
uint64_t interval)
{
- register thread_t self = current_thread();
+ thread_t self = current_thread();
uint64_t deadline;
spl_t s;
processor_t myprocessor = self->last_processor;
self->sched_pri = DEPRESSPRI;
+
+ KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHANGE_PRIORITY),
+ (uintptr_t)thread_tid(self),
+ self->base_pri,
+ self->sched_pri,
+ 0, /* eventually, 'reason' */
+ 0);
+
myprocessor->current_pri = self->sched_pri;
+ myprocessor->current_perfctl_class = thread_get_perfcontrol_class(self);
self->sched_flags |= TH_SFLAG_DEPRESS;
if (interval != 0) {
thread_lock(thread);
if (--thread->depress_timer_active == 0) {
thread->sched_flags &= ~TH_SFLAG_DEPRESSED_MASK;
- SCHED(compute_priority)(thread, FALSE);
+ thread_recompute_sched_pri(thread, FALSE);
}
thread_unlock(thread);
splx(s);
if (!(thread->sched_flags & TH_SFLAG_POLLDEPRESS)) {
if (thread->sched_flags & TH_SFLAG_DEPRESSED_MASK) {
thread->sched_flags &= ~TH_SFLAG_DEPRESSED_MASK;
- SCHED(compute_priority)(thread, FALSE);
+ thread_recompute_sched_pri(thread, FALSE);
result = KERN_SUCCESS;
}
thread_lock(self);
if (!(self->sched_flags & TH_SFLAG_DEPRESSED_MASK)) {
self->sched_pri = DEPRESSPRI;
+
+ KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHANGE_PRIORITY),
+ (uintptr_t)thread_tid(self),
+ self->base_pri,
+ self->sched_pri,
+ 0, /* eventually, 'reason' */
+ 0);
+
myprocessor->current_pri = self->sched_pri;
+ myprocessor->current_perfctl_class = thread_get_perfcontrol_class(self);
}
self->computation_epoch = abstime;
self->computation_metered = 0;
disable_preemption();
myprocessor = current_processor();
- if (SCHED(processor_queue_empty)(myprocessor) && rt_runq.count == 0) {
+ if (!SCHED(thread_should_yield)(myprocessor, current_thread())) {
mp_enable_preemption();
return;
thread_depress_abort_internal(current_thread());
}
+/*
+ * This yields to a possible non-urgent preemption pending on the current processor.
+ *
+ * This is useful when doing a long computation in the kernel without returning to userspace.
+ *
+ * As opposed to other yielding mechanisms, this does not drop the priority of the current thread.
+ */
+void
+thread_yield_to_preemption()
+{
+ /*
+ * ast_pending() should ideally be called with interrupts disabled, but
+ * the check here is fine because csw_check() will do the right thing.
+ */
+ ast_t *pending_ast = ast_pending();
+ ast_t ast = AST_NONE;
+ processor_t p;
+
+ if (*pending_ast & AST_PREEMPT) {
+ thread_t self = current_thread();
+
+ spl_t s = splsched();
+
+ p = current_processor();
+ thread_lock(self);
+ ast = csw_check(p, AST_YIELD);
+ ast_on(ast);
+ thread_unlock(self);
+
+ if (ast != AST_NONE) {
+ (void)thread_block_reason(THREAD_CONTINUE_NULL, NULL, ast);
+ }
+
+ splx(s);
+ }
+}
+
projects / apple / xnu.git / blobdiff