1 files changed, 267 insertions, 119 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index bd6fe4b7a84..2f25e68b4ba 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -44,17 +44,18 @@
 #include <asm/spu_priv1.h>
 #include "spufs.h"
 
-#define SPU_MIN_TIMESLICE 	(100 * HZ / 1000)
+#define SPU_TIMESLICE	(HZ)
 
-#define SPU_BITMAP_SIZE (((MAX_PRIO+BITS_PER_LONG)/BITS_PER_LONG)+1)
 struct spu_prio_array {
-	unsigned long bitmap[SPU_BITMAP_SIZE];
-	wait_queue_head_t waitq[MAX_PRIO];
+	DECLARE_BITMAP(bitmap, MAX_PRIO);
+	struct list_head runq[MAX_PRIO];
+	spinlock_t runq_lock;
 	struct list_head active_list[MAX_NUMNODES];
 	struct mutex active_mutex[MAX_NUMNODES];
 };
 
 static struct spu_prio_array *spu_prio;
+static struct workqueue_struct *spu_sched_wq;
 
 static inline int node_allowed(int node)
 {
@@ -68,6 +69,64 @@ static inline int node_allowed(int node)
 	return 1;
 }
 
+void spu_start_tick(struct spu_context *ctx)
+{
+	if (ctx->policy == SCHED_RR)
+		queue_delayed_work(spu_sched_wq, &ctx->sched_work, SPU_TIMESLICE);
+}
+
+void spu_stop_tick(struct spu_context *ctx)
+{
+	if (ctx->policy == SCHED_RR)
+		cancel_delayed_work(&ctx->sched_work);
+}
+
+void spu_sched_tick(struct work_struct *work)
+{
+	struct spu_context *ctx =
+		container_of(work, struct spu_context, sched_work.work);
+	struct spu *spu;
+	int rearm = 1;
+
+	mutex_lock(&ctx->state_mutex);
+	spu = ctx->spu;
+	if (spu) {
+		int best = sched_find_first_bit(spu_prio->bitmap);
+		if (best <= ctx->prio) {
+			spu_deactivate(ctx);
+			rearm = 0;
+		}
+	}
+	mutex_unlock(&ctx->state_mutex);
+
+	if (rearm)
+		spu_start_tick(ctx);
+}
+
+/**
+ * spu_add_to_active_list - add spu to active list
+ * @spu:	spu to add to the active list
+ */
+static void spu_add_to_active_list(struct spu *spu)
+{
+	mutex_lock(&spu_prio->active_mutex[spu->node]);
+	list_add_tail(&spu->list, &spu_prio->active_list[spu->node]);
+	mutex_unlock(&spu_prio->active_mutex[spu->node]);
+}
+
+/**
+ * spu_remove_from_active_list - remove spu from active list
+ * @spu:       spu to remove from the active list
+ */
+static void spu_remove_from_active_list(struct spu *spu)
+{
+	int node = spu->node;
+
+	mutex_lock(&spu_prio->active_mutex[node]);
+	list_del_init(&spu->list);
+	mutex_unlock(&spu_prio->active_mutex[node]);
+}
+
 static inline void mm_needs_global_tlbie(struct mm_struct *mm)
 {
 	int nr = (NR_CPUS > 1) ? NR_CPUS : NR_CPUS + 1;
@@ -94,8 +153,12 @@ int spu_switch_event_unregister(struct notifier_block * n)
 	return blocking_notifier_chain_unregister(&spu_switch_notifier, n);
 }
 
-
-static inline void bind_context(struct spu *spu, struct spu_context *ctx)
+/**
+ * spu_bind_context - bind spu context to physical spu
+ * @spu:	physical spu to bind to
+ * @ctx:	context to bind
+ */
+static void spu_bind_context(struct spu *spu, struct spu_context *ctx)
 {
 	pr_debug("%s: pid=%d SPU=%d NODE=%d\n", __FUNCTION__, current->pid,
 		 spu->number, spu->node);
@@ -104,7 +167,6 @@ static inline void bind_context(struct spu *spu, struct spu_context *ctx)
 	ctx->spu = spu;
 	ctx->ops = &spu_hw_ops;
 	spu->pid = current->pid;
-	spu->prio = current->prio;
 	spu->mm = ctx->owner;
 	mm_needs_global_tlbie(spu->mm);
 	spu->ibox_callback = spufs_ibox_callback;
@@ -118,12 +180,21 @@ static inline void bind_context(struct spu *spu, struct spu_context *ctx)
 	spu->timestamp = jiffies;
 	spu_cpu_affinity_set(spu, raw_smp_processor_id());
 	spu_switch_notify(spu, ctx);
+	spu_add_to_active_list(spu);
+	ctx->state = SPU_STATE_RUNNABLE;
 }
 
-static inline void unbind_context(struct spu *spu, struct spu_context *ctx)
+/**
+ * spu_unbind_context - unbind spu context from physical spu
+ * @spu:	physical spu to unbind from
+ * @ctx:	context to unbind
+ */
+static void spu_unbind_context(struct spu *spu, struct spu_context *ctx)
 {
 	pr_debug("%s: unbind pid=%d SPU=%d NODE=%d\n", __FUNCTION__,
 		 spu->pid, spu->number, spu->node);
+
+	spu_remove_from_active_list(spu);
 	spu_switch_notify(spu, NULL);
 	spu_unmap_mappings(ctx);
 	spu_save(&ctx->csa, spu);
@@ -136,95 +207,98 @@ static inline void unbind_context(struct spu *spu, struct spu_context *ctx)
 	spu->dma_callback = NULL;
 	spu->mm = NULL;
 	spu->pid = 0;
-	spu->prio = MAX_PRIO;
 	ctx->ops = &spu_backing_ops;
 	ctx->spu = NULL;
 	spu->flags = 0;
 	spu->ctx = NULL;
 }
 
-static inline void spu_add_wq(wait_queue_head_t * wq, wait_queue_t * wait,
-			      int prio)
+/**
+ * spu_add_to_rq - add a context to the runqueue
+ * @ctx:       context to add
+ */
+static void spu_add_to_rq(struct spu_context *ctx)
 {
-	prepare_to_wait_exclusive(wq, wait, TASK_INTERRUPTIBLE);
-	set_bit(prio, spu_prio->bitmap);
+	spin_lock(&spu_prio->runq_lock);
+	list_add_tail(&ctx->rq, &spu_prio->runq[ctx->prio]);
+	set_bit(ctx->prio, spu_prio->bitmap);
+	spin_unlock(&spu_prio->runq_lock);
 }
 
-static inline void spu_del_wq(wait_queue_head_t * wq, wait_queue_t * wait,
-			      int prio)
+/**
+ * spu_del_from_rq - remove a context from the runqueue
+ * @ctx:       context to remove
+ */
+static void spu_del_from_rq(struct spu_context *ctx)
 {
-	u64 flags;
-
-	__set_current_state(TASK_RUNNING);
-
-	spin_lock_irqsave(&wq->lock, flags);
+	spin_lock(&spu_prio->runq_lock);
+	list_del_init(&ctx->rq);
+	if (list_empty(&spu_prio->runq[ctx->prio]))
+		clear_bit(ctx->prio, spu_prio->bitmap);
+	spin_unlock(&spu_prio->runq_lock);
+}
 
-	remove_wait_queue_locked(wq, wait);
-	if (list_empty(&wq->task_list))
-		clear_bit(prio, spu_prio->bitmap);
+/**
+ * spu_grab_context - remove one context from the runqueue
+ * @prio:      priority of the context to be removed
+ *
+ * This function removes one context from the runqueue for priority @prio.
+ * If there is more than one context with the given priority the first
+ * task on the runqueue will be taken.
+ *
+ * Returns the spu_context it just removed.
+ *
+ * Must be called with spu_prio->runq_lock held.
+ */
+static struct spu_context *spu_grab_context(int prio)
+{
+	struct list_head *rq = &spu_prio->runq[prio];
 
-	spin_unlock_irqrestore(&wq->lock, flags);
+	if (list_empty(rq))
+		return NULL;
+	return list_entry(rq->next, struct spu_context, rq);
 }
 
-static void spu_prio_wait(struct spu_context *ctx, u64 flags)
+static void spu_prio_wait(struct spu_context *ctx)
 {
-	int prio = current->prio;
-	wait_queue_head_t *wq = &spu_prio->waitq[prio];
 	DEFINE_WAIT(wait);
 
-	if (ctx->spu)
-		return;
-
-	spu_add_wq(wq, &wait, prio);
-
+	set_bit(SPU_SCHED_WAKE, &ctx->sched_flags);
+	prepare_to_wait_exclusive(&ctx->stop_wq, &wait, TASK_INTERRUPTIBLE);
 	if (!signal_pending(current)) {
-		up_write(&ctx->state_sema);
-		pr_debug("%s: pid=%d prio=%d\n", __FUNCTION__,
-			 current->pid, current->prio);
+		mutex_unlock(&ctx->state_mutex);
 		schedule();
-		down_write(&ctx->state_sema);
+		mutex_lock(&ctx->state_mutex);
 	}
-
-	spu_del_wq(wq, &wait, prio);
+	__set_current_state(TASK_RUNNING);
+	remove_wait_queue(&ctx->stop_wq, &wait);
+	clear_bit(SPU_SCHED_WAKE, &ctx->sched_flags);
 }
 
-static void spu_prio_wakeup(void)
+/**
+ * spu_reschedule - try to find a runnable context for a spu
+ * @spu:       spu available
+ *
+ * This function is called whenever a spu becomes idle.  It looks for the
+ * most suitable runnable spu context and schedules it for execution.
+ */
+static void spu_reschedule(struct spu *spu)
 {
-	int best = sched_find_first_bit(spu_prio->bitmap);
-	if (best < MAX_PRIO) {
-		wait_queue_head_t *wq = &spu_prio->waitq[best];
-		wake_up_interruptible_nr(wq, 1);
-	}
-}
+	int best;
 
-static int get_active_spu(struct spu *spu)
-{
-	int node = spu->node;
-	struct spu *tmp;
-	int rc = 0;
+	spu_free(spu);
 
-	mutex_lock(&spu_prio->active_mutex[node]);
-	list_for_each_entry(tmp, &spu_prio->active_list[node], list) {
-		if (tmp == spu) {
-			list_del_init(&spu->list);
-			rc = 1;
-			break;
-		}
+	spin_lock(&spu_prio->runq_lock);
+	best = sched_find_first_bit(spu_prio->bitmap);
+	if (best < MAX_PRIO) {
+		struct spu_context *ctx = spu_grab_context(best);
+		if (ctx && test_bit(SPU_SCHED_WAKE, &ctx->sched_flags))
+			wake_up(&ctx->stop_wq);
 	}
-	mutex_unlock(&spu_prio->active_mutex[node]);
-	return rc;
-}
-
-static void put_active_spu(struct spu *spu)
-{
-	int node = spu->node;
-
-	mutex_lock(&spu_prio->active_mutex[node]);
-	list_add_tail(&spu->list, &spu_prio->active_list[node]);
-	mutex_unlock(&spu_prio->active_mutex[node]);
+	spin_unlock(&spu_prio->runq_lock);
 }
 
-static struct spu *spu_get_idle(struct spu_context *ctx, u64 flags)
+static struct spu *spu_get_idle(struct spu_context *ctx)
 {
 	struct spu *spu = NULL;
 	int node = cpu_to_node(raw_smp_processor_id());
@@ -241,87 +315,154 @@ static struct spu *spu_get_idle(struct spu_context *ctx, u64 flags)
 	return spu;
 }
 
-static inline struct spu *spu_get(struct spu_context *ctx, u64 flags)
+/**
+ * find_victim - find a lower priority context to preempt
+ * @ctx:	canidate context for running
+ *
+ * Returns the freed physical spu to run the new context on.
+ */
+static struct spu *find_victim(struct spu_context *ctx)
 {
-	/* Future: spu_get_idle() if possible,
-	 * otherwise try to preempt an active
-	 * context.
+	struct spu_context *victim = NULL;
+	struct spu *spu;
+	int node, n;
+
+	/*
+	 * Look for a possible preemption candidate on the local node first.
+	 * If there is no candidate look at the other nodes.  This isn't
+	 * exactly fair, but so far the whole spu schedule tries to keep
+	 * a strong node affinity.  We might want to fine-tune this in
+	 * the future.
 	 */
-	return spu_get_idle(ctx, flags);
+ restart:
+	node = cpu_to_node(raw_smp_processor_id());
+	for (n = 0; n < MAX_NUMNODES; n++, node++) {
+		node = (node < MAX_NUMNODES) ? node : 0;
+		if (!node_allowed(node))
+			continue;
+
+		mutex_lock(&spu_prio->active_mutex[node]);
+		list_for_each_entry(spu, &spu_prio->active_list[node], list) {
+			struct spu_context *tmp = spu->ctx;
+
+			if (tmp->rt_priority < ctx->rt_priority &&
+			    (!victim || tmp->rt_priority < victim->rt_priority))
+				victim = spu->ctx;
+		}
+		mutex_unlock(&spu_prio->active_mutex[node]);
+
+		if (victim) {
+			/*
+			 * This nests ctx->state_mutex, but we always lock
+			 * higher priority contexts before lower priority
+			 * ones, so this is safe until we introduce
+			 * priority inheritance schemes.
+			 */
+			if (!mutex_trylock(&victim->state_mutex)) {
+				victim = NULL;
+				goto restart;
+			}
+
+			spu = victim->spu;
+			if (!spu) {
+				/*
+				 * This race can happen because we've dropped
+				 * the active list mutex.  No a problem, just
+				 * restart the search.
+				 */
+				mutex_unlock(&victim->state_mutex);
+				victim = NULL;
+				goto restart;
+			}
+			spu_unbind_context(spu, victim);
+			mutex_unlock(&victim->state_mutex);
+			return spu;
+		}
+	}
+
+	return NULL;
 }
 
-/* The three externally callable interfaces
- * for the scheduler begin here.
+/**
+ * spu_activate - find a free spu for a context and execute it
+ * @ctx:	spu context to schedule
+ * @flags:	flags (currently ignored)
  *
- *	spu_activate	- bind a context to SPU, waiting as needed.
- *	spu_deactivate	- unbind a context from its SPU.
- *	spu_yield	- yield an SPU if others are waiting.
+ * Tries to find a free spu to run @ctx.  If no free spu is availble
+ * add the context to the runqueue so it gets woken up once an spu
+ * is available.
  */
-
-int spu_activate(struct spu_context *ctx, u64 flags)
+int spu_activate(struct spu_context *ctx, unsigned long flags)
 {
-	struct spu *spu;
-	int ret = 0;
 
-	for (;;) {
-		if (ctx->spu)
+	if (ctx->spu)
+		return 0;
+
+	do {
+		struct spu *spu;
+
+		spu = spu_get_idle(ctx);
+		/*
+		 * If this is a realtime thread we try to get it running by
+		 * preempting a lower priority thread.
+		 */
+		if (!spu && ctx->rt_priority)
+			spu = find_victim(ctx);
+		if (spu) {
+			spu_bind_context(spu, ctx);
 			return 0;
-		spu = spu_get(ctx, flags);
-		if (spu != NULL) {
-			if (ctx->spu != NULL) {
-				spu_free(spu);
-				spu_prio_wakeup();
-				break;
-			}
-			bind_context(spu, ctx);
-			put_active_spu(spu);
-			break;
 		}
-		spu_prio_wait(ctx, flags);
-		if (signal_pending(current)) {
-			ret = -ERESTARTSYS;
-			spu_prio_wakeup();
-			break;
-		}
-	}
-	return ret;
+
+		spu_add_to_rq(ctx);
+		if (!(flags & SPU_ACTIVATE_NOWAKE))
+			spu_prio_wait(ctx);
+		spu_del_from_rq(ctx);
+	} while (!signal_pending(current));
+
+	return -ERESTARTSYS;
 }
 
+/**
+ * spu_deactivate - unbind a context from it's physical spu
+ * @ctx:	spu context to unbind
+ *
+ * Unbind @ctx from the physical spu it is running on and schedule
+ * the highest priority context to run on the freed physical spu.
+ */
 void spu_deactivate(struct spu_context *ctx)
 {
-	struct spu *spu;
-	int needs_idle;
+	struct spu *spu = ctx->spu;
 
-	spu = ctx->spu;
-	if (!spu)
-		return;
-	needs_idle = get_active_spu(spu);
-	unbind_context(spu, ctx);
-	if (needs_idle) {
-		spu_free(spu);
-		spu_prio_wakeup();
+	if (spu) {
+		spu_unbind_context(spu, ctx);
+		spu_reschedule(spu);
 	}
 }
 
+/**
+ * spu_yield -  yield a physical spu if others are waiting
+ * @ctx:	spu context to yield
+ *
+ * Check if there is a higher priority context waiting and if yes
+ * unbind @ctx from the physical spu and schedule the highest
+ * priority context to run on the freed physical spu instead.
+ */
 void spu_yield(struct spu_context *ctx)
 {
 	struct spu *spu;
 	int need_yield = 0;
 
-	if (down_write_trylock(&ctx->state_sema)) {
+	if (mutex_trylock(&ctx->state_mutex)) {
 		if ((spu = ctx->spu) != NULL) {
 			int best = sched_find_first_bit(spu_prio->bitmap);
 			if (best < MAX_PRIO) {
 				pr_debug("%s: yielding SPU %d NODE %d\n",
 					 __FUNCTION__, spu->number, spu->node);
 				spu_deactivate(ctx);
-				ctx->state = SPU_STATE_SAVED;
 				need_yield = 1;
-			} else {
-				spu->prio = MAX_PRIO;
 			}
 		}
-		up_write(&ctx->state_sema);
+		mutex_unlock(&ctx->state_mutex);
 	}
 	if (unlikely(need_yield))
 		yield();
@@ -331,14 +472,19 @@ int __init spu_sched_init(void)
 {
 	int i;
 
+	spu_sched_wq = create_singlethread_workqueue("spusched");
+	if (!spu_sched_wq)
+		return 1;
+
 	spu_prio = kzalloc(sizeof(struct spu_prio_array), GFP_KERNEL);
 	if (!spu_prio) {
 		printk(KERN_WARNING "%s: Unable to allocate priority queue.\n",
 		       __FUNCTION__);
+		       destroy_workqueue(spu_sched_wq);
 		return 1;
 	}
 	for (i = 0; i < MAX_PRIO; i++) {
-		init_waitqueue_head(&spu_prio->waitq[i]);
+		INIT_LIST_HEAD(&spu_prio->runq[i]);
 		__clear_bit(i, spu_prio->bitmap);
 	}
 	__set_bit(MAX_PRIO, spu_prio->bitmap);
@@ -346,6 +492,7 @@ int __init spu_sched_init(void)
 		mutex_init(&spu_prio->active_mutex[i]);
 		INIT_LIST_HEAD(&spu_prio->active_list[i]);
 	}
+	spin_lock_init(&spu_prio->runq_lock);
 	return 0;
 }
 
@@ -364,4 +511,5 @@ void __exit spu_sched_exit(void)
 		mutex_unlock(&spu_prio->active_mutex[node]);
 	}
 	kfree(spu_prio);
+	destroy_workqueue(spu_sched_wq);
 }