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
6 * This file contains NUMA specific variables and functions which can
7 * be split away from DISCONTIGMEM and are used on NUMA machines with
10 * 2002/08/07 Erich Focht <efocht@ess.nec.de>
13 #include <linux/cpu.h>
14 #include <linux/kernel.h>
16 #include <linux/node.h>
17 #include <linux/init.h>
18 #include <linux/bootmem.h>
19 #include <linux/module.h>
20 #include <linux/random.h>
21 #include <asm/mmzone.h>
26 * The following structures are usually initialized by ACPI or
27 * similar mechanisms and describe the NUMA characteristics of the machine.
30 struct node_memblk_s node_memblk[NR_NODE_MEMBLKS];
31 struct node_cpuid_s node_cpuid[NR_CPUS] =
32 { [0 ... NR_CPUS-1] = { .phys_id = 0, .nid = NUMA_NO_NODE } };
35 * This is a matrix with "distances" between nodes, they should be
36 * proportional to the memory access latency ratios.
38 u8 numa_slit[MAX_NUMNODES * MAX_NUMNODES];
40 /* Identify which cnode a physical address resides on */
42 paddr_to_nid(unsigned long paddr)
46 for (i = 0; i < num_node_memblks; i++)
47 if (paddr >= node_memblk[i].start_paddr &&
48 paddr < node_memblk[i].start_paddr + node_memblk[i].size)
51 return (i < num_node_memblks) ? node_memblk[i].nid : (num_node_memblks ? -1 : 0);
55 * Return the bit number of a random bit set in the nodemask.
56 * (returns -1 if nodemask is empty)
58 int __node_random(const nodemask_t *maskp)
62 w = nodes_weight(*maskp);
64 bit = bitmap_ord_to_pos(maskp->bits,
65 get_random_int() % w, MAX_NUMNODES);
68 EXPORT_SYMBOL(__node_random);
70 #if defined(CONFIG_SPARSEMEM) && defined(CONFIG_NUMA)
72 * Because of holes evaluate on section limits.
73 * If the section of memory exists, then return the node where the section
74 * resides. Otherwise return node 0 as the default. This is used by
75 * SPARSEMEM to allocate the SPARSEMEM sectionmap on the NUMA node where
76 * the section resides.
78 int __meminit __early_pfn_to_nid(unsigned long pfn)
80 int i, section = pfn >> PFN_SECTION_SHIFT, ssec, esec;
82 for (i = 0; i < num_node_memblks; i++) {
83 ssec = node_memblk[i].start_paddr >> PA_SECTION_SHIFT;
84 esec = (node_memblk[i].start_paddr + node_memblk[i].size +
85 ((1L << PA_SECTION_SHIFT) - 1)) >> PA_SECTION_SHIFT;
86 if (section >= ssec && section < esec)
87 return node_memblk[i].nid;
93 #ifdef CONFIG_MEMORY_HOTPLUG
95 * SRAT information is stored in node_memblk[], then we can use SRAT
96 * information at memory-hot-add if necessary.
99 int memory_add_physaddr_to_nid(u64 addr)
101 int nid = paddr_to_nid(addr);
107 EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);