Pfair: support clustered scheduling

Just like C-EDF is a global scheduler that is split across several
clusters, Pfair can be applied on a per-cluster basis. This patch
changes the Pfair implementation to enable clustering based on the
recently added generic clustering support.

1 files changed, 274 insertions, 118 deletions

diff --git a/litmus/sched_pfair.c b/litmus/sched_pfair.c
index c7d5cf7aa2b3..71ce993df5ca 100644
--- a/litmus/sched_pfair.c
+++ b/litmus/sched_pfair.c
@@ -23,6 +23,13 @@
 
 #include <litmus/bheap.h>
 
+/* to configure the cluster size */
+#include <litmus/litmus_proc.h>
+
+#include <litmus/clustered.h>
+
+static enum cache_level pfair_cluster_level = GLOBAL_CLUSTER;
+
 struct subtask {
         /* measured in quanta relative to job release */
         quanta_t release;
@@ -43,25 +50,28 @@ struct pfair_param   {
 
         unsigned int    sporadic_release; /* On wakeup, new sporadic release? */
 
+        struct pfair_cluster* cluster; /* where this task is scheduled */
+
         struct subtask subtasks[0];   /* allocate together with pfair_param */
 };
 
 #define tsk_pfair(tsk) ((tsk)->rt_param.pfair)
 
 struct pfair_state {
-        int cpu;
+        struct cluster_cpu topology;
+
         volatile quanta_t cur_tick;    /* updated by the CPU that is advancing
                                         * the time */
         volatile quanta_t local_tick;  /* What tick is the local CPU currently
                                         * executing? Updated only by the local
                                         * CPU. In QEMU, this may lag behind the
-                                        * current tick. In a real system, with
-                                        * proper timers and aligned quanta,
-                                        * that should only be the
-                                        * case for a very short time after the
-                                        * time advanced. With staggered quanta,
-                                        * it will lag for the duration of the
-                                        * offset.
+                                        * current tick. In a real system, with
+                                        * proper timers and aligned quanta,
+                                        * that should only be the case for a
+                                        * very short time after the time
+                                        * advanced. With staggered quanta, it
+                                        * will lag for the duration of the
+                                        * offset.
                                         */
 
         struct task_struct* linked;    /* the task that should be executing */
@@ -79,25 +89,56 @@ struct pfair_state {
  */
 #define PFAIR_MAX_PERIOD 2000
 
-/* This is the release queue wheel. It is indexed by pfair_time %
- * PFAIR_MAX_PERIOD.  Each heap is ordered by PFAIR priority, so that it can be
- * merged with the ready queue.
- */
-static struct bheap release_queue[PFAIR_MAX_PERIOD];
+struct pfair_cluster {
+        struct scheduling_cluster topology;
 
-DEFINE_PER_CPU(struct pfair_state, pfair_state);
-struct pfair_state* *pstate; /* short cut */
+        /* The "global" time in this cluster. */
+        quanta_t pfair_time; /* the "official" PFAIR clock */
+        quanta_t merge_time; /* Updated after the release queue has been
+                              * merged. Used by drop_all_references().
+                              */
 
-static quanta_t pfair_time = 0; /* the "official" PFAIR clock */
-static quanta_t merge_time = 0; /* Updated after the release queue has been
-                                 * merged. Used by drop_all_references().
-                                 */
+        /* The ready queue for this cluster. */
+        rt_domain_t pfair;
 
-static rt_domain_t pfair;
+        /* This is the release queue wheel for this cluster. It is indexed by
+         * pfair_time % PFAIR_MAX_PERIOD.  Each heap is ordered by PFAIR
+         * priority, so that it can be merged with the ready queue.
+         */
+        struct bheap release_queue[PFAIR_MAX_PERIOD];
+};
 
-/* The pfair_lock is used to serialize all scheduling events.
- */
-#define pfair_lock pfair.ready_lock
+static inline struct pfair_cluster* cpu_cluster(struct pfair_state* state)
+{
+        return container_of(state->topology.cluster, struct pfair_cluster, topology);
+}
+
+static inline int cpu_id(struct pfair_state* state)
+{
+        return state->topology.id;
+}
+
+static inline struct pfair_state* from_cluster_list(struct list_head* pos)
+{
+        return list_entry(pos, struct pfair_state, topology.cluster_list);
+}
+
+static inline raw_spinlock_t* cluster_lock(struct pfair_cluster* cluster)
+{
+        /* The ready_lock is used to serialize all scheduling events. */
+        return &cluster->pfair.ready_lock;
+}
+
+static inline raw_spinlock_t* cpu_lock(struct pfair_state* state)
+{
+        return cluster_lock(cpu_cluster(state));
+}
+
+DEFINE_PER_CPU(struct pfair_state, pfair_state);
+struct pfair_state* *pstate; /* short cut */
+
+static struct pfair_cluster* pfair_clusters;
+static int num_pfair_clusters;
 
 /* Enable for lots of trace info.
  * #define PFAIR_DEBUG
@@ -197,9 +238,9 @@ int pfair_ready_order(struct bheap_node* a, struct bheap_node* b)
 }
 
 /* return the proper release queue for time t */
-static struct bheap* relq(quanta_t t)
+static struct bheap* relq(struct pfair_cluster* cluster, quanta_t t)
 {
-        struct bheap* rq = &release_queue[t % PFAIR_MAX_PERIOD];
+        struct bheap* rq = cluster->release_queue + (t % PFAIR_MAX_PERIOD);
         return rq;
 }
 
@@ -215,17 +256,19 @@ static void __pfair_add_release(struct task_struct* t, struct bheap* queue)
                     tsk_rt(t)->heap_node);
 }
 
-static void pfair_add_release(struct task_struct* t)
+static void pfair_add_release(struct pfair_cluster* cluster,
+                              struct task_struct* t)
 {
         BUG_ON(bheap_node_in_heap(tsk_rt(t)->heap_node));
-        __pfair_add_release(t, relq(cur_release(t)));
+        __pfair_add_release(t, relq(cluster, cur_release(t)));
 }
 
 /* pull released tasks from the release queue */
-static void poll_releases(quanta_t time)
+static void poll_releases(struct pfair_cluster* cluster,
+                          quanta_t time)
 {
-        __merge_ready(&pfair, relq(time));
-        merge_time = time;
+        __merge_ready(&cluster->pfair, relq(cluster, time));
+        cluster->merge_time = time;
 }
 
 static void check_preempt(struct task_struct* t)
@@ -246,18 +289,20 @@ static void check_preempt(struct task_struct* t)
         }
 }
 
-/* caller must hold pfair_lock */
+/* caller must hold pfair.ready_lock */
 static void drop_all_references(struct task_struct *t)
 {
         int cpu;
         struct pfair_state* s;
         struct bheap* q;
+        struct pfair_cluster* cluster;
         if (bheap_node_in_heap(tsk_rt(t)->heap_node)) {
                 /* figure out what queue the node is in */
-                if (time_before_eq(cur_release(t), merge_time))
-                        q = &pfair.ready_queue;
+                cluster = tsk_pfair(t)->cluster;
+                if (time_before_eq(cur_release(t), cluster->merge_time))
+                        q = &cluster->pfair.ready_queue;
                 else
-                        q = relq(cur_release(t));
+                        q = relq(cluster, cur_release(t));
                 bheap_delete(pfair_ready_order, q,
                             tsk_rt(t)->heap_node);
         }
@@ -301,22 +346,25 @@ static int advance_subtask(quanta_t time, struct task_struct* t, int cpu)
         return to_relq;
 }
 
-static void advance_subtasks(quanta_t time)
+static void advance_subtasks(struct pfair_cluster *cluster, quanta_t time)
 {
-        int cpu, missed;
+        int missed;
         struct task_struct* l;
         struct pfair_param* p;
+        struct list_head* pos;
+        struct pfair_state* cpu;
 
-        for_each_online_cpu(cpu) {
-                l = pstate[cpu]->linked;
-                missed = pstate[cpu]->linked != pstate[cpu]->local;
+        list_for_each(pos, &cluster->topology.cpus) {
+                cpu = from_cluster_list(pos);
+                l = cpu->linked;
+                missed = cpu->linked != cpu->local;
                 if (l) {
                         p = tsk_pfair(l);
                         p->last_quantum = time;
-                        p->last_cpu     =  cpu;
-                        if (advance_subtask(time, l, cpu)) {
-                                pstate[cpu]->linked = NULL;
-                                pfair_add_release(l);
+                        p->last_cpu     =  cpu_id(cpu);
+                        if (advance_subtask(time, l, cpu_id(cpu))) {
+                                cpu->linked = NULL;
+                                pfair_add_release(cluster, l);
                         }
                 }
         }
@@ -350,8 +398,10 @@ static int pfair_link(quanta_t time, int cpu,
         int target = target_cpu(time, t, cpu);
         struct task_struct* prev  = pstate[cpu]->linked;
         struct task_struct* other;
+        struct pfair_cluster* cluster = cpu_cluster(pstate[cpu]);
 
         if (target != cpu) {
+                BUG_ON(pstate[target]->topology.cluster != pstate[cpu]->topology.cluster);
                 other = pstate[target]->linked;
                 pstate[target]->linked = t;
                 tsk_rt(t)->linked_on   = target;
@@ -365,14 +415,14 @@ static int pfair_link(quanta_t time, int cpu,
                         if (prev) {
                                 /* prev got pushed back into the ready queue */
                                 tsk_rt(prev)->linked_on = NO_CPU;
-                                __add_ready(&pfair, prev);
+                                __add_ready(&cluster->pfair, prev);
                         }
                         /* we are done with this cpu */
                         return 0;
                 } else {
                         /* re-add other, it's original CPU was not considered yet */
                         tsk_rt(other)->linked_on = NO_CPU;
-                        __add_ready(&pfair, other);
+                        __add_ready(&cluster->pfair, other);
                         /* reschedule this CPU */
                         return 1;
                 }
@@ -382,71 +432,77 @@ static int pfair_link(quanta_t time, int cpu,
                 if (prev) {
                         /* prev got pushed back into the ready queue */
                         tsk_rt(prev)->linked_on = NO_CPU;
-                        __add_ready(&pfair, prev);
+                        __add_ready(&cluster->pfair, prev);
                 }
                 /* we are done with this CPU */
                 return 0;
         }
 }
 
-static void schedule_subtasks(quanta_t time)
+static void schedule_subtasks(struct pfair_cluster *cluster, quanta_t time)
 {
-        int cpu, retry;
+        int retry;
+        struct list_head *pos;
+        struct pfair_state *cpu_state;
 
-        for_each_online_cpu(cpu) {
+        list_for_each(pos, &cluster->topology.cpus) {
+                cpu_state = from_cluster_list(pos);
                 retry = 1;
                 while (retry) {
-                        if (pfair_higher_prio(__peek_ready(&pfair),
-                                              pstate[cpu]->linked))
-                                retry = pfair_link(time, cpu,
-                                                   __take_ready(&pfair));
+                        if (pfair_higher_prio(__peek_ready(&cluster->pfair),
+                                              cpu_state->linked))
+                                retry = pfair_link(time, cpu_id(cpu_state),
+                                                   __take_ready(&cluster->pfair));
                         else
                                 retry = 0;
                 }
         }
 }
 
-static void schedule_next_quantum(quanta_t time)
+static void schedule_next_quantum(struct pfair_cluster *cluster, quanta_t time)
 {
-        int cpu;
+        struct pfair_state *cpu;
+        struct list_head* pos;
 
         /* called with interrupts disabled */
         PTRACE("--- Q %lu at %llu PRE-SPIN\n",
                time, litmus_clock());
-        raw_spin_lock(&pfair_lock);
+        raw_spin_lock(cluster_lock(cluster));
         PTRACE("<<< Q %lu at %llu\n",
                time, litmus_clock());
 
         sched_trace_quantum_boundary();
 
-        advance_subtasks(time);
-        poll_releases(time);
-        schedule_subtasks(time);
+        advance_subtasks(cluster, time);
+        poll_releases(cluster, time);
+        schedule_subtasks(cluster, time);
 
-        for (cpu = 0; cpu < num_online_cpus(); cpu++)
-                if (pstate[cpu]->linked)
+        list_for_each(pos, &cluster->topology.cpus) {
+                cpu = from_cluster_list(pos);
+                if (cpu->linked)
                         PTRACE_TASK(pstate[cpu]->linked,
-                                    " linked on %d.\n", cpu);
+                                    " linked on %d.\n", cpu_id(cpu));
                 else
-                        PTRACE("(null) linked on %d.\n", cpu);
-
+                        PTRACE("(null) linked on %d.\n", cpu_id(cpu));
+        }
         /* We are done. Advance time. */
         mb();
-        for (cpu = 0; cpu < num_online_cpus(); cpu++) {
-                if (pstate[cpu]->local_tick != pstate[cpu]->cur_tick) {
+        list_for_each(pos, &cluster->topology.cpus) {
+                cpu = from_cluster_list(pos);
+                if (cpu->local_tick != cpu->cur_tick) {
                         TRACE("BAD Quantum not acked on %d "
                               "(l:%lu c:%lu p:%lu)\n",
-                              cpu,
-                              pstate[cpu]->local_tick,
-                              pstate[cpu]->cur_tick,
-                              pfair_time);
-                        pstate[cpu]->missed_quanta++;
+                              cpu_id(cpu),
+                              cpu->local_tick,
+                              cpu->cur_tick,
+                              cluster->pfair_time);
+                        cpu->missed_quanta++;
                 }
-                pstate[cpu]->cur_tick = time;
+                cpu->cur_tick = time;
         }
         PTRACE(">>> Q %lu at %llu\n",
                time, litmus_clock());
-        raw_spin_unlock(&pfair_lock);
+        raw_spin_unlock(cluster_lock(cluster));
 }
 
 static noinline void wait_for_quantum(quanta_t q, struct pfair_state* state)
@@ -479,12 +535,12 @@ static void catchup_quanta(quanta_t from, quanta_t target,
         while (time_before(cur, target)) {
                 wait_for_quantum(cur, state);
                 cur++;
-                time = cmpxchg(&pfair_time,
+                time = cmpxchg(&cpu_cluster(state)->pfair_time,
                                cur - 1,   /* expected */
                                cur        /* next     */
                         );
                 if (time == cur - 1)
-                        schedule_next_quantum(cur);
+                        schedule_next_quantum(cpu_cluster(state), cur);
         }
         TRACE("+++> catching up done\n");
 }
@@ -505,14 +561,14 @@ static void pfair_tick(struct task_struct* t)
                 /* Attempt to advance time. First CPU to get here
                  * will prepare the next quantum.
                  */
-                time = cmpxchg(&pfair_time,
+                time = cmpxchg(&cpu_cluster(state)->pfair_time,
                                cur - 1,   /* expected */
                                cur        /* next     */
                         );
                 if (time == cur - 1) {
                         /* exchange succeeded */
                         wait_for_quantum(cur - 1, state);
-                        schedule_next_quantum(cur);
+                        schedule_next_quantum(cpu_cluster(state), cur);
                         retry = 0;
                 } else if (time_before(time, cur - 1)) {
                         /* the whole system missed a tick !? */
@@ -562,59 +618,65 @@ static struct task_struct* pfair_schedule(struct task_struct * prev)
         int blocks;
         struct task_struct* next = NULL;
 
-        raw_spin_lock(&pfair_lock);
+        raw_spin_lock(cpu_lock(state));
 
         blocks  = is_realtime(prev) && !is_running(prev);
 
-        if (state->local && safe_to_schedule(state->local, state->cpu))
+        if (state->local && safe_to_schedule(state->local, cpu_id(state)))
                 next = state->local;
 
         if (prev != next) {
                 tsk_rt(prev)->scheduled_on = NO_CPU;
                 if (next)
-                        tsk_rt(next)->scheduled_on = state->cpu;
+                        tsk_rt(next)->scheduled_on = cpu_id(state);
         }
         sched_state_task_picked();
-        raw_spin_unlock(&pfair_lock);
+        raw_spin_unlock(cpu_lock(state));
 
         if (next)
                 TRACE_TASK(next, "scheduled rel=%lu at %lu (%llu)\n",
-                           tsk_pfair(next)->release, pfair_time, litmus_clock());
+                           tsk_pfair(next)->release, cpu_cluster(state)->pfair_time, litmus_clock());
         else if (is_realtime(prev))
-                TRACE("Becomes idle at %lu (%llu)\n", pfair_time, litmus_clock());
+                TRACE("Becomes idle at %lu (%llu)\n", cpu_cluster(state)->pfair_time, litmus_clock());
 
         return next;
 }
 
 static void pfair_task_new(struct task_struct * t, int on_rq, int running)
 {
-        unsigned long           flags;
+        unsigned long flags;
+        struct pfair_cluster* cluster;
 
         TRACE("pfair: task new %d state:%d\n", t->pid, t->state);
 
-        raw_spin_lock_irqsave(&pfair_lock, flags);
+        cluster = tsk_pfair(t)->cluster;
+
+        raw_spin_lock_irqsave(cluster_lock(cluster), flags);
         if (running)
                 t->rt_param.scheduled_on = task_cpu(t);
         else
                 t->rt_param.scheduled_on = NO_CPU;
 
-        prepare_release(t, pfair_time + 1);
+        prepare_release(t, cluster->pfair_time + 1);
         tsk_pfair(t)->sporadic_release = 0;
-        pfair_add_release(t);
+        pfair_add_release(cluster, t);
         check_preempt(t);
 
-        raw_spin_unlock_irqrestore(&pfair_lock, flags);
+        raw_spin_unlock_irqrestore(cluster_lock(cluster), flags);
 }
 
 static void pfair_task_wake_up(struct task_struct *t)
 {
         unsigned long flags;
         lt_t now;
+        struct pfair_cluster* cluster;
+
+        cluster = tsk_pfair(t)->cluster;
 
         TRACE_TASK(t, "wakes at %llu, release=%lu, pfair_time:%lu\n",
-                   litmus_clock(), cur_release(t), pfair_time);
+                   litmus_clock(), cur_release(t), cluster->pfair_time);
 
-        raw_spin_lock_irqsave(&pfair_lock, flags);
+        raw_spin_lock_irqsave(cluster_lock(cluster), flags);
 
         /* It is a little unclear how to deal with Pfair
          * tasks that block for a while and then wake. For now,
@@ -629,13 +691,13 @@ static void pfair_task_wake_up(struct task_struct *t)
                 prepare_release(t, time2quanta(now, CEIL));
                 sched_trace_task_release(t);
                 /* FIXME: race with pfair_time advancing */
-                pfair_add_release(t);
+                pfair_add_release(cluster, t);
                 tsk_pfair(t)->sporadic_release = 0;
         }
 
         check_preempt(t);
 
-        raw_spin_unlock_irqrestore(&pfair_lock, flags);
+        raw_spin_unlock_irqrestore(cluster_lock(cluster), flags);
         TRACE_TASK(t, "wake up done at %llu\n", litmus_clock());
 }
 
@@ -649,9 +711,12 @@ static void pfair_task_block(struct task_struct *t)
 static void pfair_task_exit(struct task_struct * t)
 {
         unsigned long flags;
+        struct pfair_cluster *cluster;
 
         BUG_ON(!is_realtime(t));
 
+        cluster = tsk_pfair(t)->cluster;
+
         /* Remote task from release or ready queue, and ensure
          * that it is not the scheduled task for ANY CPU. We
          * do this blanket check because occassionally when
@@ -659,12 +724,12 @@ static void pfair_task_exit(struct task_struct * t)
          * might not be the same as the CPU that the PFAIR scheduler
          * has chosen for it.
          */
-        raw_spin_lock_irqsave(&pfair_lock, flags);
+        raw_spin_lock_irqsave(cluster_lock(cluster), flags);
 
         TRACE_TASK(t, "RIP, state:%d\n", t->state);
         drop_all_references(t);
 
-        raw_spin_unlock_irqrestore(&pfair_lock, flags);
+        raw_spin_unlock_irqrestore(cluster_lock(cluster), flags);
 
         kfree(t->rt_param.pfair);
         t->rt_param.pfair = NULL;
@@ -676,27 +741,32 @@ static void pfair_release_at(struct task_struct* task, lt_t start)
         unsigned long flags;
         quanta_t release;
 
+        struct pfair_cluster *cluster;
+
+        cluster = tsk_pfair(task)->cluster;
+
         BUG_ON(!is_realtime(task));
 
-        raw_spin_lock_irqsave(&pfair_lock, flags);
+        raw_spin_lock_irqsave(cluster_lock(cluster), flags);
         release_at(task, start);
         release = time2quanta(start, CEIL);
 
-        if (release - pfair_time >= PFAIR_MAX_PERIOD)
-                release = pfair_time + PFAIR_MAX_PERIOD;
+        /* FIXME: support arbitrary offsets. */
+        if (release - cluster->pfair_time >= PFAIR_MAX_PERIOD)
+                release = cluster->pfair_time + PFAIR_MAX_PERIOD;
 
         TRACE_TASK(task, "sys release at %lu\n", release);
 
         drop_all_references(task);
         prepare_release(task, release);
-        pfair_add_release(task);
+        pfair_add_release(cluster, task);
 
         /* Clear sporadic release flag, since this release subsumes any
          * sporadic release on wake.
          */
         tsk_pfair(task)->sporadic_release = 0;
 
-        raw_spin_unlock_irqrestore(&pfair_lock, flags);
+        raw_spin_unlock_irqrestore(cluster_lock(cluster), flags);
 }
 
 static void init_subtask(struct subtask* sub, unsigned long i,
@@ -755,6 +825,11 @@ static long pfair_admit_task(struct task_struct* t)
         struct pfair_param* param;
         unsigned long i;
 
+        /* first check that the task is in the right cluster */
+        if (cpu_cluster(pstate[tsk_rt(t)->task_params.cpu]) !=
+            cpu_cluster(pstate[task_cpu(t)]))
+                return -EINVAL;
+
         /* Pfair is a tick-based method, so the time
          * of interest is jiffies. Calculate tick-based
          * times for everything.
@@ -798,6 +873,8 @@ static long pfair_admit_task(struct task_struct* t)
         param->release = 0;
         param->period  = period;
 
+        param->cluster = cpu_cluster(pstate[tsk_rt(t)->task_params.cpu]);
+
         for (i = 0; i < quanta; i++)
                 init_subtask(param->subtasks + i, i, quanta, period);
 
@@ -813,24 +890,88 @@ static long pfair_admit_task(struct task_struct* t)
         return 0;
 }
 
+static void pfair_init_cluster(struct pfair_cluster* cluster)
+{
+        int i;
+
+        /* initialize release queue */
+        for (i = 0; i < PFAIR_MAX_PERIOD; i++)
+                bheap_init(&cluster->release_queue[i]);
+        rt_domain_init(&cluster->pfair, pfair_ready_order, NULL, NULL);
+        INIT_LIST_HEAD(&cluster->topology.cpus);
+}
+
+static void cleanup_clusters(void)
+{
+        int i;
+
+        if (num_pfair_clusters)
+                kfree(pfair_clusters);
+        pfair_clusters = NULL;
+        num_pfair_clusters = 0;
+
+        /* avoid stale pointers */
+        for (i = 0; i < NR_CPUS; i++)
+                pstate[i]->topology.cluster = NULL;
+}
+
 static long pfair_activate_plugin(void)
 {
-        int cpu;
+        int err, i;
         struct pfair_state* state;
+        struct pfair_cluster* cluster ;
+        quanta_t now;
+        int cluster_size;
+        struct cluster_cpu* cpus[NR_CPUS];
+        struct scheduling_cluster* clust[NR_CPUS];
 
-        state = &__get_cpu_var(pfair_state);
-        pfair_time = current_quantum(state);
+        cluster_size = get_cluster_size(pfair_cluster_level);
 
-        TRACE("Activating PFAIR at q=%lu\n", pfair_time);
+        if (cluster_size <= 0 || num_online_cpus() % cluster_size != 0)
+                return -EINVAL;
 
-        for (cpu = 0; cpu < num_online_cpus(); cpu++)  {
-                state = &per_cpu(pfair_state, cpu);
-                state->cur_tick   = pfair_time;
-                state->local_tick = pfair_time;
+        num_pfair_clusters = num_online_cpus() / cluster_size;
+
+        pfair_clusters = kzalloc(num_pfair_clusters * sizeof(struct pfair_cluster), GFP_ATOMIC);
+        if (!pfair_clusters) {
+                num_pfair_clusters = 0;
+                printk(KERN_ERR "Could not allocate Pfair clusters!\n");
+                return -ENOMEM;
+        }
+
+        state = &__get_cpu_var(pfair_state);
+        now = current_quantum(state);
+        TRACE("Activating PFAIR at q=%lu\n", now);
+
+        for (i = 0; i < num_pfair_clusters; i++) {
+                cluster = &pfair_clusters[i];
+                pfair_init_cluster(cluster);
+                cluster->pfair_time = now;
+                clust[i] = &cluster->topology;
+        }
+
+        for (i = 0; i < num_online_cpus(); i++)  {
+                state = &per_cpu(pfair_state, i);
+                state->cur_tick   = now;
+                state->local_tick = now;
                 state->missed_quanta = 0;
-                state->offset     = cpu_stagger_offset(cpu);
+                state->offset     = cpu_stagger_offset(i);
+                printk(KERN_ERR "cpus[%d] set; %d\n", i, num_online_cpus());
+                cpus[i] = &state->topology;
         }
 
+        err = assign_cpus_to_clusters(pfair_cluster_level, clust, num_pfair_clusters,
+                                      cpus, num_online_cpus());
+
+        if (err < 0)
+                cleanup_clusters();
+
+        return err;
+}
+
+static long pfair_deactivate_plugin(void)
+{
+        cleanup_clusters();
         return 0;
 }
 
@@ -847,30 +988,29 @@ static struct sched_plugin pfair_plugin __cacheline_aligned_in_smp = {
         .release_at             = pfair_release_at,
         .complete_job           = complete_job,
         .activate_plugin        = pfair_activate_plugin,
+        .deactivate_plugin      = pfair_deactivate_plugin,
 };
 
+
+static struct proc_dir_entry *cluster_file = NULL, *pfair_dir = NULL;
+
 static int __init init_pfair(void)
 {
-        int cpu, i;
+        int cpu, err, fs;
         struct pfair_state *state;
 
-
         /*
          * initialize short_cut for per-cpu pfair state;
          * there may be a problem here if someone removes a cpu
          * while we are doing this initialization... and if cpus
-         * are added / removed later... is it a _real_ problem?
+         * are added / removed later... but we don't support CPU hotplug atm anyway.
          */
         pstate = kmalloc(sizeof(struct pfair_state*) * num_online_cpus(), GFP_KERNEL);
 
-        /* initialize release queue */
-        for (i = 0; i < PFAIR_MAX_PERIOD; i++)
-                bheap_init(&release_queue[i]);
-
         /* initialize CPU state */
         for (cpu = 0; cpu < num_online_cpus(); cpu++)  {
                 state = &per_cpu(pfair_state, cpu);
-                state->cpu        = cpu;
+                state->topology.id = cpu;
                 state->cur_tick   = 0;
                 state->local_tick = 0;
                 state->linked     = NULL;
@@ -881,13 +1021,29 @@ static int __init init_pfair(void)
                 pstate[cpu] = state;
         }
 
-        rt_domain_init(&pfair, pfair_ready_order, NULL, NULL);
-        return register_sched_plugin(&pfair_plugin);
+        pfair_clusters = NULL;
+        num_pfair_clusters = 0;
+
+        err = register_sched_plugin(&pfair_plugin);
+        if (!err) {
+                fs = make_plugin_proc_dir(&pfair_plugin, &pfair_dir);
+                if (!fs)
+                        cluster_file = create_cluster_file(pfair_dir, &pfair_cluster_level);
+                else
+                        printk(KERN_ERR "Could not allocate PFAIR procfs dir.\n");
+        }
+
+        return err;
 }
 
 static void __exit clean_pfair(void)
 {
         kfree(pstate);
+
+        if (cluster_file)
+                remove_proc_entry("cluster", pfair_dir);
+        if (pfair_dir)
+                remove_plugin_proc_dir(&pfair_plugin);
 }
 
 module_init(init_pfair);