[POWERPC] spufs: Fix affinity after introduction of node_allowed() calls
[cascardo/linux.git] / arch / powerpc / platforms / cell / spufs / sched.c
index 1b2916b..c784edd 100644 (file)
@@ -36,6 +36,9 @@
 #include <linux/mutex.h>
 #include <linux/notifier.h>
 #include <linux/kthread.h>
+#include <linux/pid_namespace.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 
 #include <asm/io.h>
 #include <asm/mmu_context.h>
@@ -48,10 +51,10 @@ struct spu_prio_array {
        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];
+       int nr_waiting;
 };
 
+static unsigned long spu_avenrun[3];
 static struct spu_prio_array *spu_prio;
 static struct task_struct *spusched_task;
 static struct timer_list spusched_timer;
@@ -70,11 +73,11 @@ static struct timer_list spusched_timer;
 /*
  * These are the 'tuning knobs' of the scheduler:
  *
- * Minimum timeslice is 5 msecs (or 10 jiffies, whichever is larger),
- * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
+ * Minimum timeslice is 5 msecs (or 1 spu scheduler tick, whichever is
+ * larger), default timeslice is 100 msecs, maximum timeslice is 800 msecs.
  */
-#define MIN_SPU_TIMESLICE      max(5 * HZ / 100, 10)
-#define DEF_SPU_TIMESLICE      (100 * HZ / 100)
+#define MIN_SPU_TIMESLICE      max(5 * HZ / (1000 * SPUSCHED_TICK), 1)
+#define DEF_SPU_TIMESLICE      (100 * HZ / (1000 * SPUSCHED_TICK))
 
 #define MAX_USER_PRIO          (MAX_PRIO - MAX_RT_PRIO)
 #define SCALE_PRIO(x, prio) \
@@ -96,64 +99,123 @@ void spu_set_timeslice(struct spu_context *ctx)
                ctx->time_slice = SCALE_PRIO(DEF_SPU_TIMESLICE, ctx->prio);
 }
 
-static inline int node_allowed(int node)
+/*
+ * Update scheduling information from the owning thread.
+ */
+void __spu_update_sched_info(struct spu_context *ctx)
 {
-       cpumask_t mask;
+       /*
+        * 32-Bit assignment are atomic on powerpc, and we don't care about
+        * memory ordering here because retriving the controlling thread is
+        * per defintion racy.
+        */
+       ctx->tid = current->pid;
 
-       if (!nr_cpus_node(node))
-               return 0;
-       mask = node_to_cpumask(node);
-       if (!cpus_intersects(mask, current->cpus_allowed))
-               return 0;
-       return 1;
+       /*
+        * We do our own priority calculations, so we normally want
+        * ->static_prio to start with. Unfortunately thies field
+        * contains junk for threads with a realtime scheduling
+        * policy so we have to look at ->prio in this case.
+        */
+       if (rt_prio(current->prio))
+               ctx->prio = current->prio;
+       else
+               ctx->prio = current->static_prio;
+       ctx->policy = current->policy;
+
+       /*
+        * A lot of places that don't hold list_mutex poke into
+        * cpus_allowed, including grab_runnable_context which
+        * already holds the runq_lock.  So abuse runq_lock
+        * to protect this field aswell.
+        */
+       spin_lock(&spu_prio->runq_lock);
+       ctx->cpus_allowed = current->cpus_allowed;
+       spin_unlock(&spu_prio->runq_lock);
 }
 
-/**
- * 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)
+void spu_update_sched_info(struct spu_context *ctx)
 {
-       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]);
+       int node = ctx->spu->node;
+
+       mutex_lock(&cbe_spu_info[node].list_mutex);
+       __spu_update_sched_info(ctx);
+       mutex_unlock(&cbe_spu_info[node].list_mutex);
 }
 
-static void __spu_remove_from_active_list(struct spu *spu)
+static int __node_allowed(struct spu_context *ctx, int node)
 {
-       list_del_init(&spu->list);
+       if (nr_cpus_node(node)) {
+               cpumask_t mask = node_to_cpumask(node);
+
+               if (cpus_intersects(mask, ctx->cpus_allowed))
+                       return 1;
+       }
+
+       return 0;
 }
 
-/**
- * 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)
+static int node_allowed(struct spu_context *ctx, int node)
 {
-       int node = spu->node;
+       int rval;
+
+       spin_lock(&spu_prio->runq_lock);
+       rval = __node_allowed(ctx, node);
+       spin_unlock(&spu_prio->runq_lock);
 
-       mutex_lock(&spu_prio->active_mutex[node]);
-       __spu_remove_from_active_list(spu);
-       mutex_unlock(&spu_prio->active_mutex[node]);
+       return rval;
 }
 
 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(&cbe_spu_info[node].list_mutex);
+               list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
+                       if (spu->alloc_state != SPU_FREE) {
+                               struct spu_context *ctx = spu->ctx;
+                               set_bit(SPU_SCHED_NOTIFY_ACTIVE,
+                                       &ctx->sched_flags);
+                               mb();
+                               wake_up_all(&ctx->stop_wq);
+                       }
+               }
+               mutex_unlock(&cbe_spu_info[node].list_mutex);
+       }
+}
+
 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
@@ -164,11 +226,22 @@ 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);
+       spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
+
+       if (ctx->flags & SPU_CREATE_NOSCHED)
+               atomic_inc(&cbe_spu_info[spu->node].reserved_spus);
+       if (!list_empty(&ctx->aff_list))
+               atomic_inc(&ctx->gang->aff_sched_count);
+
+       ctx->stats.slb_flt_base = spu->stats.slb_flt;
+       ctx->stats.class2_intr_base = spu->stats.class2_intr;
+
        spu->ctx = ctx;
        spu->flags = 0;
        ctx->spu = spu;
        ctx->ops = &spu_hw_ops;
        spu->pid = current->pid;
+       spu->tgid = current->tgid;
        spu_associate_mm(spu, ctx->owner);
        spu->ibox_callback = spufs_ibox_callback;
        spu->wbox_callback = spufs_wbox_callback;
@@ -182,6 +255,154 @@ static void spu_bind_context(struct spu *spu, struct spu_context *ctx)
        spu_cpu_affinity_set(spu, raw_smp_processor_id());
        spu_switch_notify(spu, ctx);
        ctx->state = SPU_STATE_RUNNABLE;
+
+       spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
+}
+
+/*
+ * Must be used with the list_mutex held.
+ */
+static inline int sched_spu(struct spu *spu)
+{
+       BUG_ON(!mutex_is_locked(&cbe_spu_info[spu->node].list_mutex));
+
+       return (!spu->ctx || !(spu->ctx->flags & SPU_CREATE_NOSCHED));
+}
+
+static void aff_merge_remaining_ctxs(struct spu_gang *gang)
+{
+       struct spu_context *ctx;
+
+       list_for_each_entry(ctx, &gang->aff_list_head, aff_list) {
+               if (list_empty(&ctx->aff_list))
+                       list_add(&ctx->aff_list, &gang->aff_list_head);
+       }
+       gang->aff_flags |= AFF_MERGED;
+}
+
+static void aff_set_offsets(struct spu_gang *gang)
+{
+       struct spu_context *ctx;
+       int offset;
+
+       offset = -1;
+       list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list,
+                                                               aff_list) {
+               if (&ctx->aff_list == &gang->aff_list_head)
+                       break;
+               ctx->aff_offset = offset--;
+       }
+
+       offset = 0;
+       list_for_each_entry(ctx, gang->aff_ref_ctx->aff_list.prev, aff_list) {
+               if (&ctx->aff_list == &gang->aff_list_head)
+                       break;
+               ctx->aff_offset = offset++;
+       }
+
+       gang->aff_flags |= AFF_OFFSETS_SET;
+}
+
+static struct spu *aff_ref_location(struct spu_context *ctx, int mem_aff,
+                int group_size, int lowest_offset)
+{
+       struct spu *spu;
+       int node, n;
+
+       /*
+        * TODO: A better algorithm could be used to find a good spu to be
+        *       used as reference location for the ctxs chain.
+        */
+       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(ctx, node))
+                       continue;
+               mutex_lock(&cbe_spu_info[node].list_mutex);
+               list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
+                       if ((!mem_aff || spu->has_mem_affinity) &&
+                                                       sched_spu(spu)) {
+                               mutex_unlock(&cbe_spu_info[node].list_mutex);
+                               return spu;
+                       }
+               }
+               mutex_unlock(&cbe_spu_info[node].list_mutex);
+       }
+       return NULL;
+}
+
+static void aff_set_ref_point_location(struct spu_gang *gang)
+{
+       int mem_aff, gs, lowest_offset;
+       struct spu_context *ctx;
+       struct spu *tmp;
+
+       mem_aff = gang->aff_ref_ctx->flags & SPU_CREATE_AFFINITY_MEM;
+       lowest_offset = 0;
+       gs = 0;
+
+       list_for_each_entry(tmp, &gang->aff_list_head, aff_list)
+               gs++;
+
+       list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list,
+                                                               aff_list) {
+               if (&ctx->aff_list == &gang->aff_list_head)
+                       break;
+               lowest_offset = ctx->aff_offset;
+       }
+
+       gang->aff_ref_spu = aff_ref_location(gang->aff_ref_ctx, mem_aff, gs,
+                                                       lowest_offset);
+}
+
+static struct spu *ctx_location(struct spu *ref, int offset, int node)
+{
+       struct spu *spu;
+
+       spu = NULL;
+       if (offset >= 0) {
+               list_for_each_entry(spu, ref->aff_list.prev, aff_list) {
+                       BUG_ON(spu->node != node);
+                       if (offset == 0)
+                               break;
+                       if (sched_spu(spu))
+                               offset--;
+               }
+       } else {
+               list_for_each_entry_reverse(spu, ref->aff_list.next, aff_list) {
+                       BUG_ON(spu->node != node);
+                       if (offset == 0)
+                               break;
+                       if (sched_spu(spu))
+                               offset++;
+               }
+       }
+
+       return spu;
+}
+
+/*
+ * affinity_check is called each time a context is going to be scheduled.
+ * It returns the spu ptr on which the context must run.
+ */
+static int has_affinity(struct spu_context *ctx)
+{
+       struct spu_gang *gang = ctx->gang;
+
+       if (list_empty(&ctx->aff_list))
+               return 0;
+
+       mutex_lock(&gang->aff_mutex);
+       if (!gang->aff_ref_spu) {
+               if (!(gang->aff_flags & AFF_MERGED))
+                       aff_merge_remaining_ctxs(gang);
+               if (!(gang->aff_flags & AFF_OFFSETS_SET))
+                       aff_set_offsets(gang);
+               aff_set_ref_point_location(gang);
+       }
+       mutex_unlock(&gang->aff_mutex);
+
+       return gang->aff_ref_spu != NULL;
 }
 
 /**
@@ -193,7 +414,13 @@ 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);
+       spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 
+       if (spu->ctx->flags & SPU_CREATE_NOSCHED)
+               atomic_dec(&cbe_spu_info[spu->node].reserved_spus);
+       if (!list_empty(&ctx->aff_list))
+               if (atomic_dec_and_test(&ctx->gang->aff_sched_count))
+                       ctx->gang->aff_ref_spu = NULL;
        spu_switch_notify(spu, NULL);
        spu_unmap_mappings(ctx);
        spu_save(&ctx->csa, spu);
@@ -206,10 +433,19 @@ static void spu_unbind_context(struct spu *spu, struct spu_context *ctx)
        spu->dma_callback = NULL;
        spu_associate_mm(spu, NULL);
        spu->pid = 0;
+       spu->tgid = 0;
        ctx->ops = &spu_backing_ops;
-       ctx->spu = NULL;
        spu->flags = 0;
        spu->ctx = NULL;
+
+       ctx->stats.slb_flt +=
+               (spu->stats.slb_flt - ctx->stats.slb_flt_base);
+       ctx->stats.class2_intr +=
+               (spu->stats.class2_intr - ctx->stats.class2_intr_base);
+
+       /* This maps the underlying spu state to idle */
+       spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
+       ctx->spu = NULL;
 }
 
 /**
@@ -218,20 +454,39 @@ static void spu_unbind_context(struct spu *spu, struct spu_context *ctx)
  */
 static void __spu_add_to_rq(struct spu_context *ctx)
 {
-       int prio = ctx->prio;
-
-       list_add_tail(&ctx->rq, &spu_prio->runq[prio]);
-       set_bit(prio, spu_prio->bitmap);
+       /*
+        * Unfortunately this code path can be called from multiple threads
+        * on behalf of a single context due to the way the problem state
+        * mmap support works.
+        *
+        * Fortunately we need to wake up all these threads at the same time
+        * and can simply skip the runqueue addition for every but the first
+        * thread getting into this codepath.
+        *
+        * It's still quite hacky, and long-term we should proxy all other
+        * threads through the owner thread so that spu_run is in control
+        * of all the scheduling activity for a given context.
+        */
+       if (list_empty(&ctx->rq)) {
+               list_add_tail(&ctx->rq, &spu_prio->runq[ctx->prio]);
+               set_bit(ctx->prio, spu_prio->bitmap);
+               if (!spu_prio->nr_waiting++)
+                       __mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
+       }
 }
 
 static void __spu_del_from_rq(struct spu_context *ctx)
 {
        int prio = ctx->prio;
 
-       if (!list_empty(&ctx->rq))
+       if (!list_empty(&ctx->rq)) {
+               if (!--spu_prio->nr_waiting)
+                       del_timer(&spusched_timer);
                list_del_init(&ctx->rq);
-       if (list_empty(&spu_prio->runq[prio]))
-               clear_bit(prio, spu_prio->bitmap);
+
+               if (list_empty(&spu_prio->runq[prio]))
+                       clear_bit(prio, spu_prio->bitmap);
+       }
 }
 
 static void spu_prio_wait(struct spu_context *ctx)
@@ -256,18 +511,41 @@ static void spu_prio_wait(struct spu_context *ctx)
 
 static struct spu *spu_get_idle(struct spu_context *ctx)
 {
-       struct spu *spu = NULL;
-       int node = cpu_to_node(raw_smp_processor_id());
-       int n;
+       struct spu *spu;
+       int node, n;
+
+       if (has_affinity(ctx)) {
+               node = ctx->gang->aff_ref_spu->node;
+
+               mutex_lock(&cbe_spu_info[node].list_mutex);
+               spu = ctx_location(ctx->gang->aff_ref_spu, ctx->aff_offset, node);
+               if (spu && spu->alloc_state == SPU_FREE)
+                       goto found;
+               mutex_unlock(&cbe_spu_info[node].list_mutex);
+               return NULL;
+       }
 
+       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))
+               if (!node_allowed(ctx, node))
                        continue;
-               spu = spu_alloc_node(node);
-               if (spu)
-                       break;
+
+               mutex_lock(&cbe_spu_info[node].list_mutex);
+               list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
+                       if (spu->alloc_state == SPU_FREE)
+                               goto found;
+               }
+               mutex_unlock(&cbe_spu_info[node].list_mutex);
        }
+
+       return NULL;
+
+ found:
+       spu->alloc_state = SPU_USED;
+       mutex_unlock(&cbe_spu_info[node].list_mutex);
+       pr_debug("Got SPU %d %d\n", spu->number, spu->node);
+       spu_init_channels(spu);
        return spu;
 }
 
@@ -294,18 +572,18 @@ static struct spu *find_victim(struct spu_context *ctx)
        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))
+               if (!node_allowed(ctx, node))
                        continue;
 
-               mutex_lock(&spu_prio->active_mutex[node]);
-               list_for_each_entry(spu, &spu_prio->active_list[node], list) {
+               mutex_lock(&cbe_spu_info[node].list_mutex);
+               list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
                        struct spu_context *tmp = spu->ctx;
 
                        if (tmp->prio > ctx->prio &&
                            (!victim || tmp->prio > victim->prio))
                                victim = spu->ctx;
                }
-               mutex_unlock(&spu_prio->active_mutex[node]);
+               mutex_unlock(&cbe_spu_info[node].list_mutex);
 
                if (victim) {
                        /*
@@ -330,8 +608,14 @@ static struct spu *find_victim(struct spu_context *ctx)
                                victim = NULL;
                                goto restart;
                        }
-                       spu_remove_from_active_list(spu);
+
+                       mutex_lock(&cbe_spu_info[node].list_mutex);
+                       cbe_spu_info[node].nr_active--;
+                       mutex_unlock(&cbe_spu_info[node].list_mutex);
+
                        spu_unbind_context(spu, victim);
+                       victim->stats.invol_ctx_switch++;
+                       spu->stats.invol_ctx_switch++;
                        mutex_unlock(&victim->state_mutex);
                        /*
                         * We need to break out of the wait loop in spu_run
@@ -357,13 +641,18 @@ static struct spu *find_victim(struct spu_context *ctx)
  */
 int spu_activate(struct spu_context *ctx, unsigned long flags)
 {
-
-       if (ctx->spu)
-               return 0;
-
        do {
                struct spu *spu;
 
+               /*
+                * If there are multiple threads waiting for a single context
+                * only one actually binds the context while the others will
+                * only be able to acquire the state_mutex once the context
+                * already is in runnable state.
+                */
+               if (ctx->spu)
+                       return 0;
+
                spu = spu_get_idle(ctx);
                /*
                 * If this is a realtime thread we try to get it running by
@@ -372,8 +661,12 @@ int spu_activate(struct spu_context *ctx, unsigned long flags)
                if (!spu && rt_prio(ctx->prio))
                        spu = find_victim(ctx);
                if (spu) {
+                       int node = spu->node;
+
+                       mutex_lock(&cbe_spu_info[node].list_mutex);
                        spu_bind_context(spu, ctx);
-                       spu_add_to_active_list(spu);
+                       cbe_spu_info[node].nr_active++;
+                       mutex_unlock(&cbe_spu_info[node].list_mutex);
                        return 0;
                }
 
@@ -389,23 +682,28 @@ int spu_activate(struct spu_context *ctx, unsigned long flags)
  * Remove the highest priority context on the runqueue and return it
  * to the caller.  Returns %NULL if no runnable context was found.
  */
-static struct spu_context *grab_runnable_context(int prio)
+static struct spu_context *grab_runnable_context(int prio, int node)
 {
-       struct spu_context *ctx = NULL;
+       struct spu_context *ctx;
        int best;
 
        spin_lock(&spu_prio->runq_lock);
-       best = sched_find_first_bit(spu_prio->bitmap);
-       if (best < prio) {
+       best = find_first_bit(spu_prio->bitmap, prio);
+       while (best < prio) {
                struct list_head *rq = &spu_prio->runq[best];
 
-               BUG_ON(list_empty(rq));
-
-               ctx = list_entry(rq->next, struct spu_context, rq);
-               __spu_del_from_rq(ctx);
+               list_for_each_entry(ctx, rq, rq) {
+                       /* XXX(hch): check for affinity here aswell */
+                       if (__node_allowed(ctx, node)) {
+                               __spu_del_from_rq(ctx);
+                               goto found;
+                       }
+               }
+               best++;
        }
+       ctx = NULL;
+ found:
        spin_unlock(&spu_prio->runq_lock);
-
        return ctx;
 }
 
@@ -415,11 +713,19 @@ static int __spu_deactivate(struct spu_context *ctx, int force, int max_prio)
        struct spu_context *new = NULL;
 
        if (spu) {
-               new = grab_runnable_context(max_prio);
+               new = grab_runnable_context(max_prio, spu->node);
                if (new || force) {
-                       spu_remove_from_active_list(spu);
+                       int node = spu->node;
+
+                       mutex_lock(&cbe_spu_info[node].list_mutex);
                        spu_unbind_context(spu, ctx);
-                       spu_free(spu);
+                       spu->alloc_state = SPU_FREE;
+                       cbe_spu_info[node].nr_active--;
+                       mutex_unlock(&cbe_spu_info[node].list_mutex);
+
+                       ctx->stats.vol_ctx_switch++;
+                       spu->stats.vol_ctx_switch++;
+
                        if (new)
                                wake_up(&new->stop_wq);
                }
@@ -442,7 +748,7 @@ void spu_deactivate(struct spu_context *ctx)
 }
 
 /**
- * spu_yield -  yield a physical spu if others are waiting
+ * 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
@@ -458,24 +764,32 @@ void spu_yield(struct spu_context *ctx)
        }
 }
 
-static void spusched_tick(struct spu_context *ctx)
+static noinline void spusched_tick(struct spu_context *ctx)
 {
-       if (ctx->policy == SCHED_FIFO || --ctx->time_slice)
+       if (ctx->flags & SPU_CREATE_NOSCHED)
+               return;
+       if (ctx->policy == SCHED_FIFO)
+               return;
+
+       if (--ctx->time_slice)
                return;
 
        /*
-        * Unfortunately active_mutex ranks outside of state_mutex, so
+        * Unfortunately list_mutex ranks outside of state_mutex, so
         * we have to trylock here.  If we fail give the context another
         * tick and try again.
         */
        if (mutex_trylock(&ctx->state_mutex)) {
-               struct spu_context *new = grab_runnable_context(ctx->prio + 1);
-               if (new) {
-                       struct spu *spu = ctx->spu;
+               struct spu *spu = ctx->spu;
+               struct spu_context *new;
 
-                       __spu_remove_from_active_list(spu);
+               new = grab_runnable_context(ctx->prio + 1, spu->node);
+               if (new) {
                        spu_unbind_context(spu, ctx);
-                       spu_free(spu);
+                       ctx->stats.invol_ctx_switch++;
+                       spu->stats.invol_ctx_switch++;
+                       spu->alloc_state = SPU_FREE;
+                       cbe_spu_info[spu->node].nr_active--;
                        wake_up(&new->stop_wq);
                        /*
                         * We need to break out of the wait loop in
@@ -491,80 +805,172 @@ static void spusched_tick(struct spu_context *ctx)
        }
 }
 
+/**
+ * count_active_contexts - count nr of active tasks
+ *
+ * Return the number of tasks currently running or waiting to run.
+ *
+ * Note that we don't take runq_lock / list_mutex here.  Reading
+ * a single 32bit value is atomic on powerpc, and we don't care
+ * about memory ordering issues here.
+ */
+static unsigned long count_active_contexts(void)
+{
+       int nr_active = 0, node;
+
+       for (node = 0; node < MAX_NUMNODES; node++)
+               nr_active += cbe_spu_info[node].nr_active;
+       nr_active += spu_prio->nr_waiting;
+
+       return nr_active;
+}
+
+/**
+ * spu_calc_load - given tick count, update the avenrun load estimates.
+ * @tick:      tick count
+ *
+ * No locking against reading these values from userspace, as for
+ * the CPU loadavg code.
+ */
+static void spu_calc_load(unsigned long ticks)
+{
+       unsigned long active_tasks; /* fixed-point */
+       static int count = LOAD_FREQ;
+
+       count -= ticks;
+
+       if (unlikely(count < 0)) {
+               active_tasks = count_active_contexts() * FIXED_1;
+               do {
+                       CALC_LOAD(spu_avenrun[0], EXP_1, active_tasks);
+                       CALC_LOAD(spu_avenrun[1], EXP_5, active_tasks);
+                       CALC_LOAD(spu_avenrun[2], EXP_15, active_tasks);
+                       count += LOAD_FREQ;
+               } while (count < 0);
+       }
+}
+
 static void spusched_wake(unsigned long data)
 {
        mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
        wake_up_process(spusched_task);
+       spu_calc_load(SPUSCHED_TICK);
 }
 
 static int spusched_thread(void *unused)
 {
-       struct spu *spu, *next;
+       struct spu *spu;
        int node;
 
-       setup_timer(&spusched_timer, spusched_wake, 0);
-       __mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
-
        while (!kthread_should_stop()) {
                set_current_state(TASK_INTERRUPTIBLE);
                schedule();
                for (node = 0; node < MAX_NUMNODES; node++) {
-                       mutex_lock(&spu_prio->active_mutex[node]);
-                       list_for_each_entry_safe(spu, next,
-                                                &spu_prio->active_list[node],
-                                                list)
-                               spusched_tick(spu->ctx);
-                       mutex_unlock(&spu_prio->active_mutex[node]);
+                       mutex_lock(&cbe_spu_info[node].list_mutex);
+                       list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list)
+                               if (spu->ctx)
+                                       spusched_tick(spu->ctx);
+                       mutex_unlock(&cbe_spu_info[node].list_mutex);
                }
        }
 
-       del_timer_sync(&spusched_timer);
        return 0;
 }
 
+#define LOAD_INT(x) ((x) >> FSHIFT)
+#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
+
+static int show_spu_loadavg(struct seq_file *s, void *private)
+{
+       int a, b, c;
+
+       a = spu_avenrun[0] + (FIXED_1/200);
+       b = spu_avenrun[1] + (FIXED_1/200);
+       c = spu_avenrun[2] + (FIXED_1/200);
+
+       /*
+        * Note that last_pid doesn't really make much sense for the
+        * SPU loadavg (it even seems very odd on the CPU side..),
+        * but we include it here to have a 100% compatible interface.
+        */
+       seq_printf(s, "%d.%02d %d.%02d %d.%02d %ld/%d %d\n",
+               LOAD_INT(a), LOAD_FRAC(a),
+               LOAD_INT(b), LOAD_FRAC(b),
+               LOAD_INT(c), LOAD_FRAC(c),
+               count_active_contexts(),
+               atomic_read(&nr_spu_contexts),
+               current->nsproxy->pid_ns->last_pid);
+       return 0;
+}
+
+static int spu_loadavg_open(struct inode *inode, struct file *file)
+{
+       return single_open(file, show_spu_loadavg, NULL);
+}
+
+static const struct file_operations spu_loadavg_fops = {
+       .open           = spu_loadavg_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = single_release,
+};
+
 int __init spu_sched_init(void)
 {
-       int i;
+       struct proc_dir_entry *entry;
+       int err = -ENOMEM, i;
 
        spu_prio = kzalloc(sizeof(struct spu_prio_array), GFP_KERNEL);
        if (!spu_prio)
-               return -ENOMEM;
+               goto out;
 
        for (i = 0; i < MAX_PRIO; i++) {
                INIT_LIST_HEAD(&spu_prio->runq[i]);
                __clear_bit(i, spu_prio->bitmap);
        }
-       __set_bit(MAX_PRIO, spu_prio->bitmap);
-       for (i = 0; i < MAX_NUMNODES; i++) {
-               mutex_init(&spu_prio->active_mutex[i]);
-               INIT_LIST_HEAD(&spu_prio->active_list[i]);
-       }
        spin_lock_init(&spu_prio->runq_lock);
 
+       setup_timer(&spusched_timer, spusched_wake, 0);
+
        spusched_task = kthread_run(spusched_thread, NULL, "spusched");
        if (IS_ERR(spusched_task)) {
-               kfree(spu_prio);
-               return PTR_ERR(spusched_task);
+               err = PTR_ERR(spusched_task);
+               goto out_free_spu_prio;
        }
+
+       entry = create_proc_entry("spu_loadavg", 0, NULL);
+       if (!entry)
+               goto out_stop_kthread;
+       entry->proc_fops = &spu_loadavg_fops;
+
+       pr_debug("spusched: tick: %d, min ticks: %d, default ticks: %d\n",
+                       SPUSCHED_TICK, MIN_SPU_TIMESLICE, DEF_SPU_TIMESLICE);
        return 0;
 
+ out_stop_kthread:
+       kthread_stop(spusched_task);
+ out_free_spu_prio:
+       kfree(spu_prio);
+ out:
+       return err;
 }
 
-void __exit spu_sched_exit(void)
+void spu_sched_exit(void)
 {
-       struct spu *spu, *tmp;
+       struct spu *spu;
        int node;
 
+       remove_proc_entry("spu_loadavg", NULL);
+
+       del_timer_sync(&spusched_timer);
        kthread_stop(spusched_task);
 
        for (node = 0; node < MAX_NUMNODES; node++) {
-               mutex_lock(&spu_prio->active_mutex[node]);
-               list_for_each_entry_safe(spu, tmp, &spu_prio->active_list[node],
-                                        list) {
-                       list_del_init(&spu->list);
-                       spu_free(spu);
-               }
-               mutex_unlock(&spu_prio->active_mutex[node]);
+               mutex_lock(&cbe_spu_info[node].list_mutex);
+               list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list)
+                       if (spu->alloc_state != SPU_FREE)
+                               spu->alloc_state = SPU_FREE;
+               mutex_unlock(&cbe_spu_info[node].list_mutex);
        }
        kfree(spu_prio);
 }