Subject: [RFC PATCH v2 1/2] powerpc: numa: enable USE_PERCPU_NUMA_NODE_ID

From: Nishanth Aravamudan <[email-masked]>
Date: Mon, 19 May 2014 11:14:23 -0700

Hi Andrew,

I found one issue with my patch, fixed below...

On 16.05.2014 [16:39:45 -0700], Nishanth Aravamudan wrote:
> Based off 3bccd996 for ia64, convert powerpc to use the generic per-CPU
> topology tracking, specifically:
>     
> 	initialize per cpu numa_node entry in start_secondary
>     	remove the powerpc cpu_to_node()
>     	define CONFIG_USE_PERCPU_NUMA_NODE_ID if NUMA
>     
> Signed-off-by: Nishanth Aravamudan <[email-masked]>

<snip>

> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index e2a4232..b95be24 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -750,6 +750,11 @@ void start_secondary(void *unused)
>  	}
>  	traverse_core_siblings(cpu, true);
>  
> +	/*
> +	 * numa_node_id() works after this.
> +	 */
> +	set_numa_node(numa_cpu_lookup_table[cpu]);
> +

Similar change is needed for the boot CPU. Update patch:

powerpc: numa: enable USE_PERCPU_NUMA_NODE_ID
    
Based off 3bccd996 for ia64, convert powerpc to use the generic per-CPU
topology tracking, specifically:
    
    initialize per cpu numa_node entry in start_secondary
    remove the powerpc cpu_to_node()
    define CONFIG_USE_PERCPU_NUMA_NODE_ID if NUMA
    
Signed-off-by: Nishanth Aravamudan <[email-masked]>

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index e099899..9125964 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -453,6 +453,10 @@ config NODES_SHIFT
 	default "4"
 	depends on NEED_MULTIPLE_NODES
 
+config USE_PERCPU_NUMA_NODE_ID
+	def_bool y
+	depends on NUMA
+
 config ARCH_SELECT_MEMORY_MODEL
 	def_bool y
 	depends on PPC64
diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
index c920215..5ecf7ea 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h
@@ -20,19 +20,6 @@ struct device_node;
 
 #include <asm/mmzone.h>
 
-static inline int cpu_to_node(int cpu)
-{
-	int nid;
-
-	nid = numa_cpu_lookup_table[cpu];
-
-	/*
-	 * During early boot, the numa-cpu lookup table might not have been
-	 * setup for all CPUs yet. In such cases, default to node 0.
-	 */
-	return (nid < 0) ? 0 : nid;
-}
-
 #define parent_node(node)	(node)
 
 #define cpumask_of_node(node) ((node) == -1 ?				\
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index e2a4232..d7252ad 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -390,6 +390,7 @@ void smp_prepare_boot_cpu(void)
 #ifdef CONFIG_PPC64
 	paca[boot_cpuid].__current = current;
 #endif
+	set_numa_node(numa_cpu_lookup_table[boot_cpuid]);
 	current_set[boot_cpuid] = task_thread_info(current);
 }
 
@@ -750,6 +751,11 @@ void start_secondary(void *unused)
 	}
 	traverse_core_siblings(cpu, true);
 
+	/*
+	 * numa_node_id() works after this.
+	 */
+	set_numa_node(numa_cpu_lookup_table[cpu]);
+
 	smp_wmb();
 	notify_cpu_starting(cpu);
 	set_cpu_online(cpu, true);