Linux内核对per-cpu变量的实现

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1. struct pcpu_chunk {
2.             struct list_head list ; / * linked to pcpu_slot lists * /
3.              int free_size ; / * free bytes in the chunk * /
4.              int contig_hint ; / * max contiguous size hint * /
5.             void * base_addr ; / * base address of this chunk * /
6.              int map_used ; / * # of map entries used * /
7.              int map_alloc ; / * # of map entries allocated * /
8.              int * map ; / * allocation map * /
9.             void * data ; / * chunk data * /
10.             bool immutable ; / * no [ de ] population allowed * /
11.             unsigned long populated [ ] ; / * populated bitmap * /
12.      } ;

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1. static struct pcpu_chunk * pcpu_create_chunk ( void )
2.      {
3.             struct pcpu_chunk * chunk ;
4.             struct vm_struct * * vms ;
6.             chunk = pcpu_alloc_chunk ( ) ;
7.              if ( ! chunk )
8.                     return NULL ;
10.             vms = pcpu_get_vm_areas ( pcpu_group_offsets , pcpu_group_sizes ,
11.                                     pcpu_nr_groups , pcpu_atom_size , GFP_KERNEL ) ;
12.              if ( ! vms ) {
13.                     pcpu_free_chunk ( chunk ) ;
14.                     return NULL ;
15.              }
17.             chunk - > data = vms ;
18.             chunk - > base_addr = vms [ 0 ] - > addr - pcpu_group_offsets [ 0 ] ;
19.             return chunk ;
20.      } static struct pcpu_chunk * pcpu_create_chunk ( void )
21.      {
22.             struct pcpu_chunk * chunk ;
23.             struct vm_struct * * vms ;
25.             chunk = pcpu_alloc_chunk ( ) ;
26.              if ( ! chunk )
27.                     return NULL ;
29.             vms = pcpu_get_vm_areas ( pcpu_group_offsets , pcpu_group_sizes ,
30.                                     pcpu_nr_groups , pcpu_atom_size , GFP_KERNEL ) ;
31.              if ( ! vms ) {
32.                     pcpu_free_chunk ( chunk ) ;
33.                     return NULL ;
34.              }
36.             chunk - > data = vms ;
37.             chunk - > base_addr = vms [ 0 ] - > addr - pcpu_group_offsets [ 0 ] ;
38.             return chunk ;
39.      }