[CELL] oprofile: enable SPU switch notification to detect currently active SPU tasks

From: Maynard Johnson <[e-mail]>

This patch adds to the capability of spu_switch_event_register so that
the caller is also notified of currently active SPU tasks.
Exports spu_switch_event_register and spu_switch_event_unregister so
that OProfile can get access to the notifications provided.

Signed-off-by: Maynard Johnson <[e-mail]>
Signed-off-by: Carl Love <[e-mail]>
Signed-off-by: Bob Nelson <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>
Acked-by: Paul Mackerras <[e-mail]>

arch/powerpc/platforms/cell/spufs/run.c

···
 	wake_up_all(&ctx->stop_wq);
 }
 
-static inline int spu_stopped(struct spu_context *ctx, u32 * stat)
+static inline int spu_stopped(struct spu_context *ctx, u32 *stat)
 {
 	struct spu *spu;
 	u64 pte_fault;
 
 	*stat = ctx->ops->status_read(ctx);
-	if (ctx->state != SPU_STATE_RUNNABLE)
-		return 1;
+
 	spu = ctx->spu;
+	if (ctx->state != SPU_STATE_RUNNABLE ||
+	    test_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags))
+		return 1;
 	pte_fault = spu->dsisr &
 	    (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED);
 	return (!(*stat & SPU_STATUS_RUNNING) || pte_fault || spu->class_0_pending) ?
···
 	return ret;
 }
 
-static int spu_run_init(struct spu_context *ctx, u32 * npc)
+static int spu_run_init(struct spu_context *ctx, u32 *npc)
 {
 	spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 
···
 	return 0;
 }
 
-static int spu_run_fini(struct spu_context *ctx, u32 * npc,
-			       u32 * status)
+static int spu_run_fini(struct spu_context *ctx, u32 *npc,
+			       u32 *status)
 {
 	int ret = 0;
 
···
 long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
 {
 	int ret;
+	struct spu *spu;
 	u32 status;
 
 	if (mutex_lock_interruptible(&ctx->run_mutex))
···
 		ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status));
 		if (unlikely(ret))
 			break;
+		spu = ctx->spu;
+		if (unlikely(test_and_clear_bit(SPU_SCHED_NOTIFY_ACTIVE,
+						&ctx->sched_flags))) {
+			if (!(status & SPU_STATUS_STOPPED_BY_STOP)) {
+				spu_switch_notify(spu, ctx);
+				continue;
+			}
+		}
 
 		spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 

arch/powerpc/platforms/cell/spufs/sched.c

···
 
 static BLOCKING_NOTIFIER_HEAD(spu_switch_notifier);
 
-static void spu_switch_notify(struct spu *spu, struct spu_context *ctx)
+void spu_switch_notify(struct spu *spu, struct spu_context *ctx)
 {
 	blocking_notifier_call_chain(&spu_switch_notifier,
 			    ctx ? ctx->object_id : 0, spu);
 }
 
+static void notify_spus_active(void)
+{
+	int node;
+
+	/*
+	 * Wake up the active spu_contexts.
+	 *
+	 * When the awakened processes see their "notify_active" flag is set,
+	 * they will call spu_switch_notify();
+	 */
+	for_each_online_node(node) {
+		struct spu *spu;
+		mutex_lock(&spu_prio->active_mutex[node]);
+		list_for_each_entry(spu, &spu_prio->active_list[node], list) {
+			struct spu_context *ctx = spu->ctx;
+			set_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags);
+			mb();	/* make sure any tasks woken up below */
+				/* can see the bit(s) set above */
+			wake_up_all(&ctx->stop_wq);
+		}
+		mutex_unlock(&spu_prio->active_mutex[node]);
+	}
+}
+
 int spu_switch_event_register(struct notifier_block * n)
 {
-	return blocking_notifier_chain_register(&spu_switch_notifier, n);
+	int ret;
+	ret = blocking_notifier_chain_register(&spu_switch_notifier, n);
+	if (!ret)
+		notify_spus_active();
+	return ret;
 }
+EXPORT_SYMBOL_GPL(spu_switch_event_register);
 
 int spu_switch_event_unregister(struct notifier_block * n)
 {
 	return blocking_notifier_chain_unregister(&spu_switch_notifier, n);
 }
+EXPORT_SYMBOL_GPL(spu_switch_event_unregister);
 
 /**
  * spu_bind_context - bind spu context to physical spu

arch/powerpc/platforms/cell/spufs/spufs.h

···
 	SPU_SCHED_WAS_ACTIVE,	/* was active upon spu_acquire_saved()  */
 };
 
+/* ctx->sched_flags */
+enum {
+	SPU_SCHED_NOTIFY_ACTIVE,
+};
+
 struct spu_context {
 	struct spu *spu;		  /* pointer to a physical SPU */
 	struct spu_state csa;		  /* SPU context save area. */
···
 int spu_activate(struct spu_context *ctx, unsigned long flags);
 void spu_deactivate(struct spu_context *ctx);
 void spu_yield(struct spu_context *ctx);
+void spu_switch_notify(struct spu *spu, struct spu_context *ctx);
 void spu_set_timeslice(struct spu_context *ctx);
 void spu_update_sched_info(struct spu_context *ctx);
 void __spu_update_sched_info(struct spu_context *ctx);