Linux節點和內存管理區的初始化

節點和管理區是內存管理中所涉及的重要概念，其數據結構在前文《linux物理內存概述》中已經介紹，現在讓我們來看看linux是如何完成節點和管理區的。

在內核首先通過setup_arch()-->paging_init()-->zone_sizes_init()來初始化節點和管理區的一些數據項

1. static void __init zone_sizes_init(void)
2. {
3. unsigned long max_zone_pfns[MAX_NR_ZONES];
4. memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
6. /*分別獲取三個管理區的頁面數*/
7. max_zone_pfns[ZONE_DMA] =
8. virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
9. max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
10. #ifdef CONFIG_HIGHMEM
11. max_zone_pfns[ZONE_HIGHMEM] = highend_pfn;
12. #endif
14. free_area_init_nodes(max_zone_pfns);
15. }

在獲取了三個管理區的頁面數後，通過free_area_init_nodes()來完成後續工作

1. void __init free_area_init_nodes(unsigned long *max_zone_pfn)
2. {
3. unsigned long nid;
4. int i;
6. /* Sort early_node_map as initialisation assumes it is sorted */
7. sort_node_map();/*將所有節點按起始頁框號排序*/
9. /* Record where the zone boundaries are */
10. /*記錄三個管理區的邊界*/
11. memset(arch_zone_lowest_possible_pfn, 0,
12. sizeof(arch_zone_lowest_possible_pfn));
13. memset(arch_zone_highest_possible_pfn, 0,
14. sizeof(arch_zone_highest_possible_pfn));
15. arch_zone_lowest_possible_pfn[0] = find_min_pfn_with_active_regions();
16. arch_zone_highest_possible_pfn[0] = max_zone_pfn[0];
17. for (i = 1; i < MAX_NR_ZONES; i++) {
18. if (i == ZONE_MOVABLE) /*不處理ZONE_MOVABLE*/
19. continue;
20. /*將下一個管理區的起始頁框置為上一個管理區的結束頁框*/
21. arch_zone_lowest_possible_pfn[i] =
22. arch_zone_highest_possible_pfn[i-1];
23. arch_zone_highest_possible_pfn[i] =
24. max(max_zone_pfn[i], arch_zone_lowest_possible_pfn[i]);
25. }
26. arch_zone_lowest_possible_pfn[ZONE_MOVABLE] = 0;
27. arch_zone_highest_possible_pfn[ZONE_MOVABLE] = 0;
29. /* Find the PFNs that ZONE_MOVABLE begins at in each node */
30. memset(zone_movable_pfn, 0, sizeof(zone_movable_pfn));
31. find_zone_movable_pfns_for_nodes(zone_movable_pfn);
33. /* Print out the zone ranges */
34. printk("Zone PFN ranges:\n");
35. for (i = 0; i < MAX_NR_ZONES; i++) {
36. if (i == ZONE_MOVABLE)
37. continue;
38. printk(" %-8s %0#10lx -> %0#10lx\n",
39. zone_names[i],
40. arch_zone_lowest_possible_pfn[i],
41. arch_zone_highest_possible_pfn[i]);
42. }
44. /* Print out the PFNs ZONE_MOVABLE begins at in each node */
45. printk("Movable zone start PFN for each node\n");
46. for (i = 0; i < MAX_NUMNODES; i++) {
47. if (zone_movable_pfn[i])
48. printk(" Node %d: %lu\n", i, zone_movable_pfn[i]);
49. }
51. /* Print out the early_node_map[] */
52. printk("early_node_map[%d] active PFN ranges\n", nr_nodemap_entries);
53. for (i = 0; i < nr_nodemap_entries; i++)
54. printk(" %3d: %0#10lx -> %0#10lx\n", early_node_map[i].nid,
55. early_node_map[i].start_pfn,
56. early_node_map[i].end_pfn);
58. /* Initialise every node */
59. mminit_verify_pageflags_layout();
60. setup_nr_node_ids();
61. for_each_online_node(nid) {/*遍歷每個節點*/
62. pg_data_t *pgdat = NODE_DATA(nid);
63. /*初始化節點*/
64. free_area_init_node(nid, NULL,
65. find_min_pfn_for_node(nid), NULL);
67. /* Any memory on that node */
68. if (pgdat->node_present_pages)
69. node_set_state(nid, N_HIGH_MEMORY);
70. check_for_regular_memory(pgdat);
71. }
72. }