Linux Kernel  3.7.1
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numa.c
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1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License. See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * This file contains NUMA specific variables and functions which can
7  * be split away from DISCONTIGMEM and are used on NUMA machines with
8  * contiguous memory.
9  *
10  * 2002/08/07 Erich Focht <[email protected]>
11  */
12 
13 #include <linux/cpu.h>
14 #include <linux/kernel.h>
15 #include <linux/mm.h>
16 #include <linux/node.h>
17 #include <linux/init.h>
18 #include <linux/bootmem.h>
19 #include <linux/module.h>
20 #include <asm/mmzone.h>
21 #include <asm/numa.h>
22 
23 
24 /*
25  * The following structures are usually initialized by ACPI or
26  * similar mechanisms and describe the NUMA characteristics of the machine.
27  */
29 struct node_memblk_s node_memblk[NR_NODE_MEMBLKS];
30 struct node_cpuid_s node_cpuid[NR_CPUS] =
31  { [0 ... NR_CPUS-1] = { .phys_id = 0, .nid = NUMA_NO_NODE } };
32 
33 /*
34  * This is a matrix with "distances" between nodes, they should be
35  * proportional to the memory access latency ratios.
36  */
38 
39 /* Identify which cnode a physical address resides on */
40 int
41 paddr_to_nid(unsigned long paddr)
42 {
43  int i;
44 
45  for (i = 0; i < num_node_memblks; i++)
46  if (paddr >= node_memblk[i].start_paddr &&
47  paddr < node_memblk[i].start_paddr + node_memblk[i].size)
48  break;
49 
50  return (i < num_node_memblks) ? node_memblk[i].nid : (num_node_memblks ? -1 : 0);
51 }
52 
53 #if defined(CONFIG_SPARSEMEM) && defined(CONFIG_NUMA)
54 /*
55  * Because of holes evaluate on section limits.
56  * If the section of memory exists, then return the node where the section
57  * resides. Otherwise return node 0 as the default. This is used by
58  * SPARSEMEM to allocate the SPARSEMEM sectionmap on the NUMA node where
59  * the section resides.
60  */
61 int __meminit __early_pfn_to_nid(unsigned long pfn)
62 {
63  int i, section = pfn >> PFN_SECTION_SHIFT, ssec, esec;
64 
65  for (i = 0; i < num_node_memblks; i++) {
66  ssec = node_memblk[i].start_paddr >> PA_SECTION_SHIFT;
67  esec = (node_memblk[i].start_paddr + node_memblk[i].size +
68  ((1L << PA_SECTION_SHIFT) - 1)) >> PA_SECTION_SHIFT;
69  if (section >= ssec && section < esec)
70  return node_memblk[i].nid;
71  }
72 
73  return -1;
74 }
75 
76 #ifdef CONFIG_MEMORY_HOTPLUG
77 /*
78  * SRAT information is stored in node_memblk[], then we can use SRAT
79  * information at memory-hot-add if necessary.
80  */
81 
82 int memory_add_physaddr_to_nid(u64 addr)
83 {
84  int nid = paddr_to_nid(addr);
85  if (nid < 0)
86  return 0;
87  return nid;
88 }
89 
90 EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
91 #endif
92 #endif