[POWERPC] spusched: fix cpu/node binding

Add a cpus_allowed allowed filed to struct spu_context so that we always
use the cpu mask of the owning thread instead of the one happening to
call into the scheduler.  Also use this information in
grab_runnable_context to avoid spurious wakeups.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

3 files changed, 52 insertions, 22 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/context.c b/arch/powerpc/platforms/cell/spufs/context.c
index c778d9178e0f..6ff2a75589f3 100644
--- a/arch/powerpc/platforms/cell/spufs/context.c
+++ b/arch/powerpc/platforms/cell/spufs/context.c
@@ -53,7 +53,7 @@ struct spu_context *alloc_spu_context(struct spu_gang *gang)
         INIT_LIST_HEAD(&ctx->rq);
         if (gang)
                 spu_gang_add_ctx(gang, ctx);
-
+        ctx->cpus_allowed = current->cpus_allowed;
         spu_set_timeslice(ctx);
         goto out;
 out_free:
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 3707c7fdbdee..69272620a6b7 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -112,6 +112,16 @@ void __spu_update_sched_info(struct spu_context *ctx)
         else
                 ctx->prio = current->static_prio;
         ctx->policy = current->policy;
+
+        /*
+         * A lot of places that don't hold active_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);
 }
 
 void spu_update_sched_info(struct spu_context *ctx)
@@ -123,16 +133,27 @@ void spu_update_sched_info(struct spu_context *ctx)
         mutex_unlock(&spu_prio->active_mutex[node]);
 }
 
-static inline int node_allowed(int node)
+static int __node_allowed(struct spu_context *ctx, int node)
 {
-        cpumask_t mask;
+        if (nr_cpus_node(node)) {
+                cpumask_t mask = node_to_cpumask(node);
 
-        if (!nr_cpus_node(node))
-                return 0;
-        mask = node_to_cpumask(node);
-        if (!cpus_intersects(mask, current->cpus_allowed))
-                return 0;
-        return 1;
+                if (cpus_intersects(mask, ctx->cpus_allowed))
+                        return 1;
+        }
+
+        return 0;
+}
+
+static int node_allowed(struct spu_context *ctx, int node)
+{
+        int rval;
+
+        spin_lock(&spu_prio->runq_lock);
+        rval = __node_allowed(ctx, node);
+        spin_unlock(&spu_prio->runq_lock);
+
+        return rval;
 }
 
 /**
@@ -289,7 +310,7 @@ static struct spu *spu_get_idle(struct spu_context *ctx)
 
         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)
@@ -321,7 +342,7 @@ 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]);
@@ -416,23 +437,28 @@ 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) {
+        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;
 }
 
@@ -442,7 +468,7 @@ 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);
                         spu_unbind_context(spu, ctx);
@@ -496,9 +522,11 @@ static void spusched_tick(struct spu_context *ctx)
          * tick and try again.
          */
         if (mutex_trylock(&ctx->state_mutex)) {
-                struct spu_context *new = grab_runnable_context(ctx->prio + 1);
+                struct spu *spu = ctx->spu;
+                struct spu_context *new;
+
+                new = grab_runnable_context(ctx->prio + 1, spu->node);
                 if (new) {
-                        struct spu *spu = ctx->spu;
 
                         __spu_remove_from_active_list(spu);
                         spu_unbind_context(spu, ctx);
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index ff77f904fa31..98d3c18b2b6f 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -26,6 +26,7 @@
 #include <linux/mutex.h>
 #include <linux/spinlock.h>
 #include <linux/fs.h>
+#include <linux/cpumask.h>
 
 #include <asm/spu.h>
 #include <asm/spu_csa.h>
@@ -80,6 +81,7 @@ struct spu_context {
         struct list_head rq;
         unsigned int time_slice;
         unsigned long sched_flags;
+        cpumask_t cpus_allowed;
         int policy;
         int prio;
 };