lkml.org 
[lkml]   [2003]   [Jan]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] (2/7) 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 -urpN -X /home/fletch/.diff.exclude 01-apicid_to_node/arch/i386/kernel/smpboot.c 02-i386_caching_topo/arch/i386/kernel/smpboot.c
--- 01-apicid_to_node/arch/i386/kernel/smpboot.c Thu Jan 2 22:04:58 2003
+++ 02-i386_caching_topo/arch/i386/kernel/smpboot.c Tue Jan 7 09:24:51 2003
@@ -503,6 +503,39 @@ static struct task_struct * __init fork_
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_apici
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_api
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 -urpN -X /home/fletch/.diff.exclude 01-apicid_to_node/include/asm-i386/topology.h 02-i386_caching_topo/include/asm-i386/topology.h
--- 01-apicid_to_node/include/asm-i386/topology.h Sun Nov 17 20:29:26 2002
+++ 02-i386_caching_topo/include/asm-i386/topology.h Tue Jan 7 09:24:51 2003
@@ -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_cp

#include <asm-generic/topology.h>

-#endif /* CONFIG_X86_NUMAQ */
+#endif /* CONFIG_NUMA */

#endif /* _ASM_I386_TOPOLOGY_H */
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:32    [W:0.038 / U:2.324 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site