[PATCH] spufs: set irq affinity for running threads

For far, all SPU triggered interrupts always end up on
the first SMT thread, which is a bad solution.

This patch implements setting the affinity to the
CPU that was running last when entering execution on
an SPU. This should result in a significant reduction
in IPI calls and better cache locality for SPE thread
specific data.

Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

4 files changed, 40 insertions, 16 deletions

diff --git a/arch/powerpc/platforms/cell/interrupt.c b/arch/powerpc/platforms/cell/interrupt.c
index 7fbe78a9327d..63aa52acf441 100644
--- a/arch/powerpc/platforms/cell/interrupt.c
+++ b/arch/powerpc/platforms/cell/interrupt.c
@@ -23,6 +23,7 @@
 #include <linux/config.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/module.h>
 #include <linux/percpu.h>
 #include <linux/types.h>
 
@@ -55,6 +56,7 @@ struct iic_regs {
 
 struct iic {
         struct iic_regs __iomem *regs;
+        u8 target_id;
 };
 
 static DEFINE_PER_CPU(struct iic, iic);
@@ -172,12 +174,11 @@ int iic_get_irq(struct pt_regs *regs)
         return irq;
 }
 
-static struct iic_regs __iomem *find_iic(int cpu)
+static int setup_iic(int cpu, struct iic *iic)
 {
         struct device_node *np;
         int nodeid = cpu / 2;
         unsigned long regs;
-        struct iic_regs __iomem *iic_regs;
 
         for (np = of_find_node_by_type(NULL, "cpu");
              np;
@@ -188,20 +189,23 @@ static struct iic_regs __iomem *find_iic(int cpu)
 
         if (!np) {
                 printk(KERN_WARNING "IIC: CPU %d not found\n", cpu);
-                iic_regs = NULL;
-        } else {
-                regs = *(long *)get_property(np, "iic", NULL);
-
-                /* hack until we have decided on the devtree info */
-                regs += 0x400;
-                if (cpu & 1)
-                        regs += 0x20;
-
-                printk(KERN_DEBUG "IIC for CPU %d at %lx\n", cpu, regs);
-                iic_regs = __ioremap(regs, sizeof(struct iic_regs),
-                                                 _PAGE_NO_CACHE);
+                iic->regs = NULL;
+                iic->target_id = 0xff;
+                return -ENODEV;
         }
-        return iic_regs;
+
+        regs = *(long *)get_property(np, "iic", NULL);
+
+        /* hack until we have decided on the devtree info */
+        regs += 0x400;
+        if (cpu & 1)
+                regs += 0x20;
+
+        printk(KERN_DEBUG "IIC for CPU %d at %lx\n", cpu, regs);
+        iic->regs = __ioremap(regs, sizeof(struct iic_regs),
+                                         _PAGE_NO_CACHE);
+        iic->target_id = (nodeid << 4) + ((cpu & 1) ? 0xf : 0xe);
+        return 0;
 }
 
 #ifdef CONFIG_SMP
@@ -227,6 +231,12 @@ void iic_cause_IPI(int cpu, int mesg)
         out_be64(&per_cpu(iic, cpu).regs->generate, (IIC_NUM_IPIS - 1 - mesg) << 4);
 }
 
+u8 iic_get_target_id(int cpu)
+{
+        return per_cpu(iic, cpu).target_id;
+}
+EXPORT_SYMBOL_GPL(iic_get_target_id);
+
 static irqreturn_t iic_ipi_action(int irq, void *dev_id, struct pt_regs *regs)
 {
         smp_message_recv(iic_irq_to_ipi(irq), regs);
@@ -276,7 +286,7 @@ void iic_init_IRQ(void)
         irq_offset = 0;
         for_each_cpu(cpu) {
                 iic = &per_cpu(iic, cpu);
-                iic->regs = find_iic(cpu);
+                setup_iic(cpu, iic);
                 if (iic->regs)
                         out_be64(&iic->regs->prio, 0xff);
         }
diff --git a/arch/powerpc/platforms/cell/interrupt.h b/arch/powerpc/platforms/cell/interrupt.h
index 37d58e6fd0c6..a14bd38791c0 100644
--- a/arch/powerpc/platforms/cell/interrupt.h
+++ b/arch/powerpc/platforms/cell/interrupt.h
@@ -54,6 +54,7 @@ extern void iic_setup_cpu(void);
 extern void iic_local_enable(void);
 extern void iic_local_disable(void);
 
+extern u8 iic_get_target_id(int cpu);
 
 extern void spider_init_IRQ(void);
 extern int spider_get_irq(unsigned long int_pending);
diff --git a/arch/powerpc/platforms/cell/spu_base.c b/arch/powerpc/platforms/cell/spu_base.c
index 7fe3fa3da0e9..d75ae03df686 100644
--- a/arch/powerpc/platforms/cell/spu_base.c
+++ b/arch/powerpc/platforms/cell/spu_base.c
@@ -507,6 +507,14 @@ int spu_irq_class_1_bottom(struct spu *spu)
         return ret;
 }
 
+void spu_irq_setaffinity(struct spu *spu, int cpu)
+{
+        u64 target = iic_get_target_id(cpu);
+        u64 route = target << 48 | target << 32 | target << 16;
+        spu_int_route_set(spu, route);
+}
+EXPORT_SYMBOL_GPL(spu_irq_setaffinity);
+
 static void __iomem * __init map_spe_prop(struct device_node *n,
                                                  const char *name)
 {
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index c34198c29159..963182fbd1aa 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -357,6 +357,11 @@ int spu_activate(struct spu_context *ctx, u64 flags)
         if (!spu)
                 return (signal_pending(current)) ? -ERESTARTSYS : -EAGAIN;
         bind_context(spu, ctx);
+        /*
+         * We're likely to wait for interrupts on the same
+         * CPU that we are now on, so send them here.
+         */
+        spu_irq_setaffinity(spu, raw_smp_processor_id());
         put_active_spu(spu);
         return 0;
 }