[PATCH] make i386 topology caching

Patch originally by Matt Dobson. Reworked a little by me.

Stores the mappings between cpus and nodes in an array, instead of
working them out every time. Gives about 4% off systime for kernel
compile (we use these for every page allocation), and removes one
of the two only usages of apicid->cpu mapping, which is really awkward
to keep for systems with large apic spaces, and is genererally pretty
useless anyway (later patch removes).

diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index b602e889879f8dffc6d83757c2dae1bd2c8e1b73..26b28b7f5391f7c4f60e7821dda9157af4d3b86e 100644 (file)
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -503,6 +503,39 @@ static struct task_struct * __init fork_by_hand(void)
        return do_fork(CLONE_VM|CLONE_IDLETASK, 0, &regs, 0, NULL, NULL);
 }
 
+#ifdef CONFIG_NUMA
+
+/* which logical CPUs are on which nodes */
+volatile unsigned long node_2_cpu_mask[MAX_NR_NODES] = 
+                                               { [0 ... MAX_NR_NODES-1] = 0 };
+/* which node each logical CPU is on */
+volatile int cpu_2_node[NR_CPUS] = { [0 ... NR_CPUS-1] = 0 };
+
+/* set up a mapping between cpu and node. */
+static inline void map_cpu_to_node(int cpu, int node)
+{
+       printk("Mapping cpu %d to node %d\n", cpu, node);
+       node_2_cpu_mask[node] |= (1 << cpu);
+       cpu_2_node[cpu] = node;
+}
+
+/* undo a mapping between cpu and node. */
+static inline void unmap_cpu_to_node(int cpu)
+{
+       int node;
+
+       printk("Unmapping cpu %d from all nodes\n", cpu);
+       for (node = 0; node < MAX_NR_NODES; node ++)
+               node_2_cpu_mask[node] &= ~(1 << cpu);
+       cpu_2_node[cpu] = -1;
+}
+#else /* !CONFIG_NUMA */
+
+#define map_cpu_to_node(cpu, node)     ({})
+#define unmap_cpu_to_node(cpu) ({})
+
+#endif /* CONFIG_NUMA */
+
 /* which physical APIC ID maps to which logical CPU number */
 volatile int physical_apicid_2_cpu[MAX_APICID];
 /* which logical CPU number maps to which physical APIC ID */
@@ -537,6 +570,7 @@ static inline void map_cpu_to_boot_apicid(int cpu, int apicid)
        if (clustered_apic_mode) {
                logical_apicid_2_cpu[apicid] = cpu;     
                cpu_2_logical_apicid[cpu] = apicid;
+               map_cpu_to_node(cpu, apicid_to_node(apicid));
        } else {
                physical_apicid_2_cpu[apicid] = cpu;    
                cpu_2_physical_apicid[cpu] = apicid;
@@ -552,6 +586,7 @@ static inline void unmap_cpu_to_boot_apicid(int cpu, int apicid)
        if (clustered_apic_mode) {
                logical_apicid_2_cpu[apicid] = -1;      
                cpu_2_logical_apicid[cpu] = -1;
+               unmap_cpu_to_node(cpu);
        } else {
                physical_apicid_2_cpu[apicid] = -1;     
                cpu_2_physical_apicid[cpu] = -1;

diff --git a/include/asm-i386/topology.h b/include/asm-i386/topology.h
index d3bdbb0c40c6fd789ca56b9436e99ac8857d44fd..3609d59e8c300e33e882f3f2b9bcc94bb4bcc935 100644 (file)
--- a/include/asm-i386/topology.h
+++ b/include/asm-i386/topology.h
@@ -27,12 +27,17 @@
 #ifndef _ASM_I386_TOPOLOGY_H
 #define _ASM_I386_TOPOLOGY_H
 
-#ifdef CONFIG_X86_NUMAQ
+#ifdef CONFIG_NUMA
 
-#include <asm/smpboot.h>
+/* Mappings between logical cpu number and node number */
+extern volatile unsigned long node_2_cpu_mask[];
+extern volatile int cpu_2_node[];
 
 /* Returns the number of the node containing CPU 'cpu' */
-#define __cpu_to_node(cpu) (cpu_to_logical_apicid(cpu) >> 4)
+static inline int __cpu_to_node(int cpu)
+{ 
+       return cpu_2_node[cpu];
+}
 
 /* Returns the number of the node containing MemBlk 'memblk' */
 #define __memblk_to_node(memblk) (memblk)
@@ -41,49 +46,22 @@
    so it is a pretty simple function! */
 #define __parent_node(node) (node)
 
-/* Returns the number of the first CPU on Node 'node'.
- * This should be changed to a set of cached values
- * but this will do for now.
- */
-static inline int __node_to_first_cpu(int node)
-{
-       int i, cpu, logical_apicid = node << 4;
-
-       for(i = 1; i < 16; i <<= 1)
-               /* check to see if the cpu is in the system */
-               if ((cpu = logical_apicid_to_cpu(logical_apicid | i)) >= 0)
-                       /* if yes, return it to caller */
-                       return cpu;
-
-       BUG(); /* couldn't find a cpu on given node */
-       return -1;
-}
-
-/* Returns a bitmask of CPUs on Node 'node'.
- * This should be changed to a set of cached bitmasks
- * but this will do for now.
- */
+/* Returns a bitmask of CPUs on Node 'node'. */
 static inline unsigned long __node_to_cpu_mask(int node)
 {
-       int i, cpu, logical_apicid = node << 4;
-       unsigned long mask = 0UL;
-
-       if (sizeof(unsigned long) * 8 < NR_CPUS)
-               BUG();
-
-       for(i = 1; i < 16; i <<= 1)
-               /* check to see if the cpu is in the system */
-               if ((cpu = logical_apicid_to_cpu(logical_apicid | i)) >= 0)
-                       /* if yes, add to bitmask */
-                       mask |= 1 << cpu;
+       return node_2_cpu_mask[node];
+}
 
-       return mask;
+/* Returns the number of the first CPU on Node 'node'. */
+static inline int __node_to_first_cpu(int node)
+{ 
+       return __ffs(__node_to_cpu_mask(node));
 }
 
 /* Returns the number of the first MemBlk on Node 'node' */
 #define __node_to_memblk(node) (node)
 
-#else /* !CONFIG_X86_NUMAQ */
+#else /* !CONFIG_NUMA */
 /*
  * Other i386 platforms should define their own version of the 
  * above macros here.
@@ -91,6 +69,6 @@ static inline unsigned long __node_to_cpu_mask(int node)
 
 #include <asm-generic/topology.h>
 
-#endif /* CONFIG_X86_NUMAQ */
+#endif /* CONFIG_NUMA */
 
 #endif /* _ASM_I386_TOPOLOGY_H */