[Cbe-oss-dev] [PATCH 3:3] spusched: Fix spu interrupt routing

[Luke Browning]

Fix spu interrupt routing

Route mfc interrupts to the cpu where the controlling thread last ran
provided that cpu is on the same node as the spu.  Otherwise don't 
reroute interrupts.  Code previously routed to the current cpu which could 
may have been on a remote node.  In the case of time slicing all spu 
interrupts were routed to the same cpu.  This should improve performance 
and provide a more predictable environment for processing spu exceptions.  
In the past we have seen concurrent delivery of spu exceptions to 
two cpus. This eliminates that concern. 

Signed-off-by: Luke Browning <lukebr at linux.vnet.ibm.com>

---

Index: spufs/arch/powerpc/platforms/cell/spu_priv1_mmio.c
===================================================================
--- spufs.orig/arch/powerpc/platforms/cell/spu_priv1_mmio.c
+++ spufs/arch/powerpc/platforms/cell/spu_priv1_mmio.c
@@ -75,8 +75,18 @@ static u64 int_stat_get(struct spu *spu,
 
 static void cpu_affinity_set(struct spu *spu, int cpu)
 {
-	u64 target = iic_get_target_id(cpu);
-	u64 route = target << 48 | target << 32 | target << 16;
+	u64 target;
+	u64 route;
+
+	if (nr_cpus_node(spu->node)) {
+		cpumask_t mask = node_to_cpumask(spu->node);
+
+		if (!cpus_intersects(mask, cpu))
+			return;
+	}
+
+	target = iic_get_target_id(cpu);
+	route = target << 48 | target << 32 | target << 16;
 	out_be64(&spu->priv1->int_route_RW, route);
 }
 
Index: spufs/arch/powerpc/platforms/cell/spufs/sched.c
===================================================================
--- spufs.orig/arch/powerpc/platforms/cell/spufs/sched.c
+++ spufs/arch/powerpc/platforms/cell/spufs/sched.c
@@ -140,6 +140,9 @@ void __spu_update_sched_info(struct spu_
 	 * if it is timesliced or preempted.
 	 */
 	ctx->cpus_allowed = current->cpus_allowed;
+
+	/* Save the current cpu id for spu interrupt routing. */
+	ctx->last_ran = raw_smp_processor_id();
 }
 
 void spu_update_sched_info(struct spu_context *ctx)
@@ -242,7 +245,6 @@ static void spu_bind_context(struct spu 
 	spu_unmap_mappings(ctx);
 	spu_restore(&ctx->csa, spu);
 	spu->timestamp = jiffies;
-	spu_cpu_affinity_set(spu, raw_smp_processor_id());
 	spu_switch_notify(spu, ctx);
 	ctx->state = SPU_STATE_RUNNABLE;
 
Index: spufs/arch/powerpc/platforms/cell/spufs/spufs.h
===================================================================
--- spufs.orig/arch/powerpc/platforms/cell/spufs/spufs.h
+++ spufs/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -97,6 +97,7 @@ struct spu_context {
 	cpumask_t cpus_allowed;
 	int policy;
 	int prio;
+	int last_ran;
 
 	/* statistics */
 	struct {
Index: spufs/arch/powerpc/platforms/cell/spufs/switch.c
===================================================================
--- spufs.orig/arch/powerpc/platforms/cell/spufs/switch.c
+++ spufs/arch/powerpc/platforms/cell/spufs/switch.c
@@ -1705,6 +1705,15 @@ static inline void restore_mfc_sr1(struc
 	eieio();
 }
 
+static inline void set_mfc_int_route(struct spu_state *csa, struct spu *spu)
+{
+	struct spu_context *ctx;
+
+	ctx = container_of(csa, struct spu_context, csa);
+
+	spu_cpu_affinity_set(spu, ctx->last_ran);
+}
+
 static inline void restore_other_spu_access(struct spu_state *csa,
 					    struct spu *spu)
 {
@@ -2015,6 +2024,7 @@ static void restore_csa(struct spu_state
 	check_ppuint_mb_stat(next, spu);	/* Step 67. */
 	spu_invalidate_slbs(spu);		/* Modified Step 68. */
 	restore_mfc_sr1(next, spu);	        /* Step 69. */
+	set_mfc_int_route(next, spu);		/* NEW      */
 	restore_other_spu_access(next, spu);	/* Step 70. */
 	restore_spu_runcntl(next, spu);	        /* Step 71. */
 	restore_mfc_cntl(next, spu);	        /* Step 72. */