Worker: Performance cleaning of fast-path in task pushers unblocking (e75079fd) · Commits · 戴 / Bird

sysdep/unix/worker.c

+24 −14

Original line number	Diff line number	Diff line
		@@ -916,16 +916,23 @@ worker_loop(void *_data UNUSED)
		while (1) {
		WQ_LOCK_PREFETCH(wq->pending.head, NULL);

		uint blocked = 0;
		if (!prepended)
		blocked = atomic_load_explicit(&wq->blocked, memory_order_relaxed);

		if (!SEM_TRYWAIT(&wq->waiting))
		{
		WDBG("Worker will wait\n");
		if (!prepended)
		if (atomic_load_explicit(&wq->blocked, memory_order_relaxed))
		atomic_fetch_add_explicit(&wq->postponed, 1, memory_order_relaxed);
		else
		WORKER_YIELD();

		/* If no work is waiting, we must release the available-semaphore */
		SEM_POST(&wq->available);

		/* And also flush all the postponed semaphores */
		uint postponed = atomic_exchange_explicit(&wq->postponed, 0, memory_order_relaxed);
		for (uint i=0; i<postponed; i++)
		SEM_POST(&wq->available);

		WORKER_YIELD();
		SEM_WAIT(&wq->waiting);
		WORKER_CONTINUE();
		WDBG("Worker woken up\n");
		@@ -933,8 +940,11 @@ worker_loop(void *_data UNUSED)
		else
		{
		WDBG("Worker won't wait\n");
		if (!prepended)
		if (atomic_load_explicit(&wq->blocked, memory_order_relaxed))

		if (blocked)
		/* There are some task_push() calls blocked. We keep them blocked
		* until the queue is processed to prevent unnecessary semaphore
		* calls and context switches. */
		atomic_fetch_add_explicit(&wq->postponed, 1, memory_order_relaxed);
		else
		SEM_POST(&wq->available);
		@@ -949,14 +959,14 @@ worker_loop(void *_data UNUSED)
		struct task *t = HEAD(wq->pending);
		rem_node(&t->n);

		/* Check list for emptiness */
		/* Check worker queue for emptiness */
		int empty = EMPTY_LIST(wq->pending);

		/* No more operations on worker queue */
		WQ_UNLOCK();

		/* Flush the postponed available semaphores */
		if (empty && atomic_load_explicit(&wq->postponed, memory_order_relaxed))
		/* Flush the postponed available semaphores if the queue is empty */
		if (empty)
		{
		uint postponed = atomic_exchange_explicit(&wq->postponed, 0, memory_order_relaxed);
		for (uint i=0; i<postponed; i++)

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