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

From: Maynard Johnson <mpjohn@us.ibm.com>

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 <mpjohn@us.ibm.com>
Signed-off-by: Carl Love <carll@us.ibm.com>
Signed-off-by: Bob Nelson <rrnelson@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>

3 files changed, 55 insertions, 8 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/run.c b/arch/powerpc/platforms/cell/spufs/run.c
index c0238ea5b55a..0b50fa5cb39d 100644
--- a/arch/powerpc/platforms/cell/spufs/run.c
+++ b/arch/powerpc/platforms/cell/spufs/run.c
@@ -18,15 +18,17 @@ void spufs_stop_callback(struct spu *spu)
         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) ?
@@ -124,7 +126,7 @@ out:
         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);
 
@@ -158,8 +160,8 @@ static int spu_run_init(struct spu_context *ctx, u32 * npc)
         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;
 
@@ -298,6 +300,7 @@ static inline int spu_process_events(struct spu_context *ctx)
 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))
@@ -333,6 +336,14 @@ long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
                 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);
 
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 49b8f6867a96..88ec333e90d3 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -204,21 +204,51 @@ static void spu_remove_from_active_list(struct spu *spu)
 
 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
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index 42d8da8f0fb5..692dbd0edc37 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -44,6 +44,11 @@ enum {
         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. */
@@ -240,6 +245,7 @@ void spu_release_saved(struct spu_context *ctx);
 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);