root/include/linux/swapctl.h

/* */

INCLUDED FROM

DEFINITIONS

1. AGE_CLUSTER_SIZE
2. touch_page
3. age_page
4. age_of
5. set_page_new

   1 #ifndef _LINUX_SWAPCTL_H
   2 #define _LINUX_SWAPCTL_H
   3 
   4 #include <asm/page.h>
   5 #include <linux/fs.h>
   6 
   7 /* Swap tuning control */
   8 
   9 /* First, enumerate the different reclaim policies */
  10 enum RCL_POLICY {RCL_ROUND_ROBIN, RCL_BUFF_FIRST, RCL_PERSIST};
  11 
  12 typedef struct swap_control_v5
  13 {
  14         int     sc_max_page_age;
  15         int     sc_page_advance;
  16         int     sc_page_decline;
  17         int     sc_page_initial_age;
  18         int     sc_max_buff_age;
  19         int     sc_buff_advance;
  20         int     sc_buff_decline;
  21         int     sc_buff_initial_age;
  22         int     sc_age_cluster_fract;
  23         int     sc_age_cluster_min;
  24         int     sc_pageout_weight;
  25         int     sc_bufferout_weight;
  26         int     sc_buffer_grace;
  27         int     sc_nr_buffs_to_free;
  28         int     sc_nr_pages_to_free;
  29         enum RCL_POLICY sc_policy;
  30 } swap_control_v5;
  31 typedef struct swap_control_v5 swap_control_t;
  32 extern swap_control_t swap_control;
  33 
  34 typedef struct kswapd_control_v1
  35 {
  36         int     maxpages;
  37         int     pages_buff;
  38         int     pages_shm;
  39         int     pages_mmap;
  40         int     pages_swap;
  41 } kswapd_control_v1;
  42 typedef kswapd_control_v1 kswapd_control_t;
  43 extern kswapd_control_t kswapd_ctl;
  44 
  45 typedef struct swapstat_v1
  46 {
  47         int     wakeups;
  48         int     pages_reclaimed;
  49         int     pages_shm;
  50         int     pages_mmap;
  51         int     pages_swap;
  52 } swapstat_v1;
  53 typedef swapstat_v1 swapstat_t;
  54 extern swapstat_t swapstats;
  55 
  56 extern int min_free_pages, free_pages_low, free_pages_high;
  57 
  58 #define SC_VERSION      1
  59 #define SC_MAX_VERSION  1
  60 
  61 #ifdef __KERNEL__
  62 
  63 /* Define the maximum (least urgent) priority for the page reclaim code */
  64 #define RCL_MAXPRI 6
  65 /* We use an extra priority in the swap accounting code to represent
  66    failure to free a resource at any priority */
  67 #define RCL_FAILURE (RCL_MAXPRI + 1)
  68 
  69 #define RCL_POLICY              (swap_control.sc_policy)
  70 #define AGE_CLUSTER_FRACT       (swap_control.sc_age_cluster_fract)
  71 #define AGE_CLUSTER_MIN         (swap_control.sc_age_cluster_min)
  72 #define PAGEOUT_WEIGHT          (swap_control.sc_pageout_weight)
  73 #define BUFFEROUT_WEIGHT        (swap_control.sc_bufferout_weight)
  74 
  75 #define NR_BUFFS_TO_FREE        (swap_control.sc_nr_buffs_to_free)
  76 #define NR_PAGES_TO_FREE        (swap_control.sc_nr_pages_to_free)
  77 
  78 #define BUFFERMEM_GRACE         (swap_control.sc_buffer_grace)
  79 
  80 /* Page aging (see mm/swap.c) */
  81 
  82 #define MAX_PAGE_AGE            (swap_control.sc_max_page_age)
  83 #define PAGE_ADVANCE            (swap_control.sc_page_advance)
  84 #define PAGE_DECLINE            (swap_control.sc_page_decline)
  85 #define PAGE_INITIAL_AGE        (swap_control.sc_page_initial_age)
  86 
  87 #define MAX_BUFF_AGE            (swap_control.sc_max_buff_age)
  88 #define BUFF_ADVANCE            (swap_control.sc_buff_advance)
  89 #define BUFF_DECLINE            (swap_control.sc_buff_decline)
  90 #define BUFF_INITIAL_AGE        (swap_control.sc_buff_initial_age)
  91 
  92 /* Given a resource of N units (pages or buffers etc), we only try to
  93  * age and reclaim AGE_CLUSTER_FRACT per 1024 resources each time we
  94  * scan the resource list. */
  95 static inline int AGE_CLUSTER_SIZE(int resources)
     /*  */
  96 {
  97         int n = (resources * AGE_CLUSTER_FRACT) >> 10;
  98         if (n < AGE_CLUSTER_MIN)
  99                 return AGE_CLUSTER_MIN;
 100         else
 101                 return n;
 102 }
 103 
 104 static inline void touch_page(struct page *page)
     /*  */
 105 {
 106         if (page->age < (MAX_PAGE_AGE - PAGE_ADVANCE))
 107                 page->age += PAGE_ADVANCE;
 108         else
 109                 page->age = MAX_PAGE_AGE;
 110 }
 111 
 112 static inline void age_page(struct page *page)
     /*  */
 113 {
 114         if (page->age > PAGE_DECLINE)
 115                 page->age -= PAGE_DECLINE;
 116         else
 117                 page->age = 0;
 118 }
 119 
 120 static inline int age_of(unsigned long addr)
     /*  */
 121 {
 122         return mem_map[MAP_NR(addr)].age;
 123 }
 124 
 125 static inline void set_page_new(unsigned long addr)
     /*  */
 126 {
 127         mem_map[MAP_NR(addr)].age = PAGE_INITIAL_AGE;
 128 }
 129 
 130 #endif /* __KERNEL */
 131 
 132 #endif /* _LINUX_SWAPCTL_H */

/* */