kernel: Allow threads to yield CPU properly
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bab69bdb47
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03e3a82953
@ -15,6 +15,7 @@
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#include <OS.h>
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#include <AutoDeleter.h>
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#include <cpu.h>
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#include <debug.h>
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#include <int.h>
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@ -43,7 +44,10 @@ const bigtime_t kThreadQuantum = 3000;
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// The run queue. Holds the threads ready to run ordered by priority.
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static RunQueue<Thread, THREAD_MAX_SET_PRIORITY>* sRunQueue;
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typedef RunQueue<Thread, THREAD_MAX_SET_PRIORITY> SimpleRunQueue;
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static SimpleRunQueue* sRunQueue;
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static SimpleRunQueue* sExpiredQueue;
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static int32 sYieldedThreadPriority = -1;
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struct scheduler_thread_data {
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@ -80,14 +84,11 @@ scheduler_thread_data::Init()
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}
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static int
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dump_run_queue(int argc, char **argv)
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static inline void
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dump_queue(RunQueue<Thread, THREAD_MAX_SET_PRIORITY>::ConstIterator& iterator)
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{
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RunQueue<Thread, THREAD_MAX_SET_PRIORITY>::ConstIterator iterator;
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iterator = sRunQueue->GetConstIterator();
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if (!iterator.HasNext())
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kprintf("Run queue is empty!\n");
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kprintf("Queue is empty.\n");
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else {
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kprintf("thread id priority penalty name\n");
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while (iterator.HasNext()) {
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@ -100,11 +101,33 @@ dump_run_queue(int argc, char **argv)
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schedulerThreadData->priority_penalty, thread->name);
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}
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}
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}
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static int
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dump_run_queue(int argc, char **argv)
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{
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RunQueue<Thread, THREAD_MAX_SET_PRIORITY>::ConstIterator iterator;
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kprintf("Current run queue:\n");
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iterator = sRunQueue->GetConstIterator();
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dump_queue(iterator);
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kprintf("\nExpired run queue:\n");
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iterator = sExpiredQueue->GetConstIterator();
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dump_queue(iterator);
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return 0;
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}
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static inline void
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simple_yield(Thread* thread)
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{
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TRACE("thread %ld yielded\n", thread->id);
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sYieldedThreadPriority = max_c(sYieldedThreadPriority, thread->priority);
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}
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static inline int32
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simple_get_effective_priority(Thread *thread)
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{
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@ -120,8 +143,9 @@ simple_get_effective_priority(Thread *thread)
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if (schedulerThreadData->forced_yield_count != 0
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&& schedulerThreadData->forced_yield_count % kYieldFrequency == 0) {
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TRACE("forcing thread %ld to yield\n", thread->id);
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effectivePriority = B_LOWEST_ACTIVE_PRIORITY;
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} else
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simple_yield(thread);
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}
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effectivePriority -= schedulerThreadData->priority_penalty;
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}
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@ -188,7 +212,11 @@ simple_enqueue_in_run_queue(Thread *thread)
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scheduler_thread_data* schedulerThreadData
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= reinterpret_cast<scheduler_thread_data*>(thread->scheduler_data);
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if (threadPriority <= sYieldedThreadPriority)
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sExpiredQueue->PushBack(thread, threadPriority);
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else
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sRunQueue->PushBack(thread, threadPriority);
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thread->next_priority = thread->priority;
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schedulerThreadData->cpu_bound = true;
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schedulerThreadData->time_left = 0;
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@ -358,6 +386,10 @@ simple_reschedule(void)
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else
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simple_cancel_penalty(oldThread);
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if (oldThread->was_yielded)
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simple_yield(oldThread);
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oldThread->was_yielded = false;
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TRACE("enqueueing thread %ld into run queue priority = %ld\n",
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oldThread->id, simple_get_effective_priority(oldThread));
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simple_enqueue_in_run_queue(oldThread);
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@ -385,7 +417,26 @@ simple_reschedule(void)
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schedulerOldThreadData->lost_cpu = false;
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// select thread with the biggest priority
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do {
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nextThread = sRunQueue->PeekMaximum();
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if (sYieldedThreadPriority >= 0 && nextThread != NULL
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&& thread_is_idle_thread(nextThread)) {
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sRunQueue->Remove(nextThread);
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simple_enqueue_in_run_queue(nextThread);
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continue;
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}
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break;
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} while (true);
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if (nextThread == NULL && sYieldedThreadPriority >= 0) {
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RunQueue<Thread, THREAD_MAX_SET_PRIORITY>* temp = sRunQueue;
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sRunQueue = sExpiredQueue;
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sExpiredQueue = temp;
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sYieldedThreadPriority = -1;
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nextThread = sRunQueue->PeekMaximum();
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}
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if (!nextThread)
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panic("reschedule(): run queue is empty!\n");
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@ -399,7 +450,6 @@ simple_reschedule(void)
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nextThread->state = B_THREAD_RUNNING;
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nextThread->next_state = B_THREAD_READY;
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oldThread->was_yielded = false;
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// track kernel time (user time is tracked in thread_at_kernel_entry())
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scheduler_update_thread_times(oldThread, nextThread);
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@ -490,20 +540,26 @@ static scheduler_ops kSimpleOps = {
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status_t
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scheduler_simple_init()
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{
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sRunQueue = new(std::nothrow) RunQueue<Thread, THREAD_MAX_SET_PRIORITY>;
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sRunQueue = new(std::nothrow) SimpleRunQueue;
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if (sRunQueue == NULL)
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return B_NO_MEMORY;
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ObjectDeleter<SimpleRunQueue> runQueueDeleter(sRunQueue);
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sExpiredQueue = new(std::nothrow) SimpleRunQueue;
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if (sExpiredQueue == NULL)
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return B_NO_MEMORY;
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ObjectDeleter<SimpleRunQueue> expiredQueueDeleter(sExpiredQueue);
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status_t result = sRunQueue->GetInitStatus();
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if (result != B_OK) {
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delete sRunQueue;
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if (result != B_OK)
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return result;
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}
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gScheduler = &kSimpleOps;
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add_debugger_command_etc("run_queue", &dump_run_queue,
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"List threads in run queue", "\nLists threads in run queue", 0);
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runQueueDeleter.Detach();
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expiredQueueDeleter.Detach();
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return B_OK;
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}
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@ -2447,11 +2447,6 @@ void
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thread_yield(bool force)
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{
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if (force) {
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// snooze for roughly 3 thread quantums
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snooze_etc(9000, B_SYSTEM_TIMEBASE, B_RELATIVE_TIMEOUT | B_CAN_INTERRUPT);
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#if 0
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cpu_status state;
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Thread *thread = thread_get_current_thread();
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if (thread == NULL)
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return;
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@ -2459,10 +2454,8 @@ thread_yield(bool force)
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InterruptsSpinLocker _(gSchedulerLock);
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// mark the thread as yielded, so it will not be scheduled next
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//thread->was_yielded = true;
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thread->next_priority = B_LOWEST_ACTIVE_PRIORITY;
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thread->was_yielded = true;
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scheduler_reschedule();
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#endif
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} else {
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Thread *thread = thread_get_current_thread();
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if (thread == NULL)
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