3 files changed, 58 insertions, 15 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/context.c b/arch/powerpc/platforms/cell/spufs/context.c
index f084667e4f50..c5ec7cfc24b5 100644
--- a/arch/powerpc/platforms/cell/spufs/context.c
+++ b/arch/powerpc/platforms/cell/spufs/context.c
@@ -53,10 +53,19 @@ struct spu_context *alloc_spu_context(struct spu_gang *gang)
         INIT_LIST_HEAD(&ctx->rq);
         if (gang)
                 spu_gang_add_ctx(gang, ctx);
-        ctx->rt_priority = current->rt_priority;
+
+        /*
+         * 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;
-        ctx->prio = current->prio;
-        ctx->time_slice = SPU_DEF_TIMESLICE;
+        spu_set_timeslice(ctx);
         goto out;
 out_free:
         kfree(ctx);
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index d673353b6d33..1b2916bdc1c8 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -44,10 +44,6 @@
 #include <asm/spu_priv1.h>
 #include "spufs.h"
 
-#define SPU_TIMESLICE   (HZ)
-
-#define SPUSCHED_TICK   (HZ / 100)
-
 struct spu_prio_array {
         DECLARE_BITMAP(bitmap, MAX_PRIO);
         struct list_head runq[MAX_PRIO];
@@ -60,6 +56,46 @@ static struct spu_prio_array *spu_prio;
 static struct task_struct *spusched_task;
 static struct timer_list spusched_timer;
 
+/*
+ * Priority of a normal, non-rt, non-niced'd process (aka nice level 0).
+ */
+#define NORMAL_PRIO             120
+
+/*
+ * Frequency of the spu scheduler tick.  By default we do one SPU scheduler
+ * tick for every 10 CPU scheduler ticks.
+ */
+#define SPUSCHED_TICK           (10)
+
+/*
+ * 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.
+ */
+#define MIN_SPU_TIMESLICE       max(5 * HZ / 100, 10)
+#define DEF_SPU_TIMESLICE       (100 * HZ / 100)
+
+#define MAX_USER_PRIO           (MAX_PRIO - MAX_RT_PRIO)
+#define SCALE_PRIO(x, prio) \
+        max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_SPU_TIMESLICE)
+
+/*
+ * scale user-nice values [ -20 ... 0 ... 19 ] to time slice values:
+ * [800ms ... 100ms ... 5ms]
+ *
+ * The higher a thread's priority, the bigger timeslices
+ * it gets during one round of execution. But even the lowest
+ * priority thread gets MIN_TIMESLICE worth of execution time.
+ */
+void spu_set_timeslice(struct spu_context *ctx)
+{
+        if (ctx->prio < NORMAL_PRIO)
+                ctx->time_slice = SCALE_PRIO(DEF_SPU_TIMESLICE * 4, ctx->prio);
+        else
+                ctx->time_slice = SCALE_PRIO(DEF_SPU_TIMESLICE, ctx->prio);
+}
+
 static inline int node_allowed(int node)
 {
         cpumask_t mask;
@@ -265,8 +301,8 @@ static struct spu *find_victim(struct spu_context *ctx)
                 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))
+                        if (tmp->prio > ctx->prio &&
+                            (!victim || tmp->prio > victim->prio))
                                 victim = spu->ctx;
                 }
                 mutex_unlock(&spu_prio->active_mutex[node]);
@@ -333,7 +369,7 @@ int spu_activate(struct spu_context *ctx, unsigned long flags)
                  * If this is a realtime thread we try to get it running by
                  * preempting a lower priority thread.
                  */
-                if (!spu && ctx->rt_priority)
+                if (!spu && rt_prio(ctx->prio))
                         spu = find_victim(ctx);
                 if (spu) {
                         spu_bind_context(spu, ctx);
@@ -424,7 +460,7 @@ void spu_yield(struct spu_context *ctx)
 
 static void spusched_tick(struct spu_context *ctx)
 {
-        if (ctx->policy != SCHED_RR || --ctx->time_slice)
+        if (ctx->policy == SCHED_FIFO || --ctx->time_slice)
                 return;
 
         /*
@@ -448,7 +484,7 @@ static void spusched_tick(struct spu_context *ctx)
                          */
                         wake_up(&ctx->stop_wq);
                 }
-                ctx->time_slice = SPU_DEF_TIMESLICE;
+                spu_set_timeslice(ctx);
                 mutex_unlock(&ctx->state_mutex);
         } else {
                 ctx->time_slice++;
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index 8068171dfa9c..fddc59c204b5 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -31,8 +31,6 @@
 #include <asm/spu_csa.h>
 #include <asm/spu_info.h>
 
-#define SPU_DEF_TIMESLICE       100
-
 /* The magic number for our file system */
 enum {
         SPUFS_MAGIC = 0x23c9b64e,
@@ -82,7 +80,6 @@ struct spu_context {
         struct list_head rq;
         unsigned int time_slice;
         unsigned long sched_flags;
-        unsigned long rt_priority;
         int policy;
         int prio;
 };
@@ -197,6 +194,7 @@ void spu_acquire_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_set_timeslice(struct spu_context *ctx);
 int __init spu_sched_init(void);
 void __exit spu_sched_exit(void);