include/linux/mmzone.h

   1 #ifndef _LINUX_MMZONE_H
   2 #define _LINUX_MMZONE_H
   3
   4 #ifdef __KERNEL__
   5 #ifndef __ASSEMBLY__
   6
   7 #include <linux/config.h>
   8 #include <linux/spinlock.h>
   9 #include <linux/list.h>
  10 #include <linux/wait.h>
  11 #include <linux/cache.h>
  12 #include <linux/threads.h>
  13 #include <linux/numa.h>
  14 #include <linux/init.h>
  15 #include <asm/atomic.h>
  16
  17 /* Free memory management - zoned buddy allocator.  */
  18 #ifndef CONFIG_FORCE_MAX_ZONEORDER
  19 #define MAX_ORDER 11
  20 #else
  21 #define MAX_ORDER CONFIG_FORCE_MAX_ZONEORDER
  22 #endif
  23
  24 struct free_area {
  25         struct list_head        free_list;
  26         unsigned long           nr_free;
  27 };
  28
  29 struct pglist_data;
  30
  31 /*
  32  * zone->lock and zone->lru_lock are two of the hottest locks in the kernel.
  33  * So add a wild amount of padding here to ensure that they fall into separate
  34  * cachelines.  There are very few zone structures in the machine, so space
  35  * consumption is not a concern here.
  36  */
  37 #if defined(CONFIG_SMP)
  38 struct zone_padding {
  39         char x[0];
  40 } ____cacheline_maxaligned_in_smp;
  41 #define ZONE_PADDING(name)      struct zone_padding name;
  42 #else
  43 #define ZONE_PADDING(name)
  44 #endif
  45
  46 struct per_cpu_pages {
  47         int count;              /* number of pages in the list */
  48         int low;                /* low watermark, refill needed */
  49         int high;               /* high watermark, emptying needed */
  50         int batch;              /* chunk size for buddy add/remove */
  51         struct list_head list;  /* the list of pages */
  52 };
  53
  54 struct per_cpu_pageset {
  55         struct per_cpu_pages pcp[2];    /* 0: hot.  1: cold */
  56 #ifdef CONFIG_NUMA
  57         unsigned long numa_hit;         /* allocated in intended node */
  58         unsigned long numa_miss;        /* allocated in non intended node */
  59         unsigned long numa_foreign;     /* was intended here, hit elsewhere */
  60         unsigned long interleave_hit;   /* interleaver prefered this zone */
  61         unsigned long local_node;       /* allocation from local node */
  62         unsigned long other_node;       /* allocation from other node */
  63 #endif
  64 } ____cacheline_aligned_in_smp;
  65
  66 #define ZONE_DMA                0
  67 #define ZONE_NORMAL             1
  68 #define ZONE_HIGHMEM            2
  69
  70 #define MAX_NR_ZONES            3       /* Sync this with ZONES_SHIFT */
  71 #define ZONES_SHIFT             2       /* ceil(log2(MAX_NR_ZONES)) */
  72
  73
  74 /*
  75  * When a memory allocation must conform to specific limitations (such
  76  * as being suitable for DMA) the caller will pass in hints to the
  77  * allocator in the gfp_mask, in the zone modifier bits.  These bits
  78  * are used to select a priority ordered list of memory zones which
  79  * match the requested limits.  GFP_ZONEMASK defines which bits within
  80  * the gfp_mask should be considered as zone modifiers.  Each valid
  81  * combination of the zone modifier bits has a corresponding list
  82  * of zones (in node_zonelists).  Thus for two zone modifiers there
  83  * will be a maximum of 4 (2 ** 2) zonelists, for 3 modifiers there will
  84  * be 8 (2 ** 3) zonelists.  GFP_ZONETYPES defines the number of possible
  85  * combinations of zone modifiers in "zone modifier space".
  86  */
  87 #define GFP_ZONEMASK    0x03
  88 /*
  89  * As an optimisation any zone modifier bits which are only valid when
  90  * no other zone modifier bits are set (loners) should be placed in
  91  * the highest order bits of this field.  This allows us to reduce the
  92  * extent of the zonelists thus saving space.  For example in the case
  93  * of three zone modifier bits, we could require up to eight zonelists.
  94  * If the left most zone modifier is a "loner" then the highest valid
  95  * zonelist would be four allowing us to allocate only five zonelists.
  96  * Use the first form when the left most bit is not a "loner", otherwise
  97  * use the second.
  98  */
  99 /* #define GFP_ZONETYPES        (GFP_ZONEMASK + 1) */           /* Non-loner */
 100 #define GFP_ZONETYPES   ((GFP_ZONEMASK + 1) / 2 + 1)            /* Loner */
 101
 102 /*
 103  * On machines where it is needed (eg PCs) we divide physical memory
 104  * into multiple physical zones. On a PC we have 3 zones:
 105  *
 106  * ZONE_DMA       < 16 MB       ISA DMA capable memory
 107  * ZONE_NORMAL  16-896 MB       direct mapped by the kernel
 108  * ZONE_HIGHMEM  > 896 MB       only page cache and user processes
 109  */
 110
 111 struct zone {
 112         /* Fields commonly accessed by the page allocator */
 113         unsigned long           free_pages;
 114         unsigned long           pages_min, pages_low, pages_high;
 115         /*
 116          * We don't know if the memory that we're going to allocate will be freeable
 117          * or/and it will be released eventually, so to avoid totally wasting several
 118          * GB of ram we must reserve some of the lower zone memory (otherwise we risk
 119          * to run OOM on the lower zones despite there's tons of freeable ram
 120          * on the higher zones). This array is recalculated at runtime if the
 121          * sysctl_lowmem_reserve_ratio sysctl changes.
 122          */
 123         unsigned long           lowmem_reserve[MAX_NR_ZONES];
 124
 125         struct per_cpu_pageset  pageset[NR_CPUS];
 126
 127         /*
 128          * free areas of different sizes
 129          */
 130         spinlock_t              lock;
 131         struct free_area        free_area[MAX_ORDER];
 132
 133
 134         ZONE_PADDING(_pad1_)
 135
 136         /* Fields commonly accessed by the page reclaim scanner */
 137         spinlock_t              lru_lock;
 138         struct list_head        active_list;
 139         struct list_head        inactive_list;
 140         unsigned long           nr_scan_active;
 141         unsigned long           nr_scan_inactive;
 142         unsigned long           nr_active;
 143         unsigned long           nr_inactive;
 144         unsigned long           pages_scanned;     /* since last reclaim */
 145         int                     all_unreclaimable; /* All pages pinned */
 146
 147         /*
 148          * prev_priority holds the scanning priority for this zone.  It is
 149          * defined as the scanning priority at which we achieved our reclaim
 150          * target at the previous try_to_free_pages() or balance_pgdat()
 151          * invokation.
 152          *
 153          * We use prev_priority as a measure of how much stress page reclaim is
 154          * under - it drives the swappiness decision: whether to unmap mapped
 155          * pages.
 156          *
 157          * temp_priority is used to remember the scanning priority at which
 158          * this zone was successfully refilled to free_pages == pages_high.
 159          *
 160          * Access to both these fields is quite racy even on uniprocessor.  But
 161          * it is expected to average out OK.
 162          */
 163         int temp_priority;
 164         int prev_priority;
 165
 166
 167         ZONE_PADDING(_pad2_)
 168         /* Rarely used or read-mostly fields */
 169
 170         /*
 171          * wait_table           -- the array holding the hash table
 172          * wait_table_size      -- the size of the hash table array
 173          * wait_table_bits      -- wait_table_size == (1 << wait_table_bits)
 174          *
 175          * The purpose of all these is to keep track of the people
 176          * waiting for a page to become available and make them
 177          * runnable again when possible. The trouble is that this
 178          * consumes a lot of space, especially when so few things
 179          * wait on pages at a given time. So instead of using
 180          * per-page waitqueues, we use a waitqueue hash table.
 181          *
 182          * The bucket discipline is to sleep on the same queue when
 183          * colliding and wake all in that wait queue when removing.
 184          * When something wakes, it must check to be sure its page is
 185          * truly available, a la thundering herd. The cost of a
 186          * collision is great, but given the expected load of the
 187          * table, they should be so rare as to be outweighed by the
 188          * benefits from the saved space.
 189          *
 190          * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
 191          * primary users of these fields, and in mm/page_alloc.c
 192          * free_area_init_core() performs the initialization of them.
 193          */
 194         wait_queue_head_t       * wait_table;
 195         unsigned long           wait_table_size;
 196         unsigned long           wait_table_bits;
 197
 198         /*
 199          * Discontig memory support fields.
 200          */
 201         struct pglist_data      *zone_pgdat;
 202         struct page             *zone_mem_map;
 203         /* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
 204         unsigned long           zone_start_pfn;
 205
 206         unsigned long           spanned_pages;  /* total size, including holes */
 207         unsigned long           present_pages;  /* amount of memory (excluding holes) */
 208
 209         /*
 210          * rarely used fields:
 211          */
 212         char                    *name;
 213 } ____cacheline_maxaligned_in_smp;
 214
 215
 216 /*
 217  * The "priority" of VM scanning is how much of the queues we will scan in one
 218  * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
 219  * queues ("queue_length >> 12") during an aging round.
 220  */
 221 #define DEF_PRIORITY 12
 222
 223 /*
 224  * One allocation request operates on a zonelist. A zonelist
 225  * is a list of zones, the first one is the 'goal' of the
 226  * allocation, the other zones are fallback zones, in decreasing
 227  * priority.
 228  *
 229  * Right now a zonelist takes up less than a cacheline. We never
 230  * modify it apart from boot-up, and only a few indices are used,
 231  * so despite the zonelist table being relatively big, the cache
 232  * footprint of this construct is very small.
 233  */
 234 struct zonelist {
 235         struct zone *zones[MAX_NUMNODES * MAX_NR_ZONES + 1]; // NULL delimited
 236 };
 237
 238
 239 /*
 240  * The pg_data_t structure is used in machines with CONFIG_DISCONTIGMEM
 241  * (mostly NUMA machines?) to denote a higher-level memory zone than the
 242  * zone denotes.
 243  *
 244  * On NUMA machines, each NUMA node would have a pg_data_t to describe
 245  * it's memory layout.
 246  *
 247  * Memory statistics and page replacement data structures are maintained on a
 248  * per-zone basis.
 249  */
 250 struct bootmem_data;
 251 typedef struct pglist_data {
 252         struct zone node_zones[MAX_NR_ZONES];
 253         struct zonelist node_zonelists[GFP_ZONETYPES];
 254         int nr_zones;
 255         struct page *node_mem_map;
 256         struct bootmem_data *bdata;
 257         unsigned long node_start_pfn;
 258         unsigned long node_present_pages; /* total number of physical pages */
 259         unsigned long node_spanned_pages; /* total size of physical page
 260                                              range, including holes */
 261         int node_id;
 262         struct pglist_data *pgdat_next;
 263         wait_queue_head_t kswapd_wait;
 264         struct task_struct *kswapd;
 265         int kswapd_max_order;
 266 } pg_data_t;
 267
 268 #define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
 269 #define node_spanned_pages(nid) (NODE_DATA(nid)->node_spanned_pages)
 270
 271 extern struct pglist_data *pgdat_list;
 272
 273 void __get_zone_counts(unsigned long *active, unsigned long *inactive,
 274                         unsigned long *free, struct pglist_data *pgdat);
 275 void get_zone_counts(unsigned long *active, unsigned long *inactive,
 276                         unsigned long *free);
 277 void build_all_zonelists(void);
 278 void wakeup_kswapd(struct zone *zone, int order);
 279 int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
 280                 int alloc_type, int can_try_harder, int gfp_high);
 281
 282 #ifdef CONFIG_HAVE_MEMORY_PRESENT
 283 void memory_present(int nid, unsigned long start, unsigned long end);
 284 #else
 285 static inline void memory_present(int nid, unsigned long start, unsigned long end) {}
 286 #endif
 287
 288 #ifdef CONFIG_NEED_NODE_MEMMAP_SIZE
 289 unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
 290 #endif
 291
 292 /*
 293  * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
 294  */
 295 #define zone_idx(zone)          ((zone) - (zone)->zone_pgdat->node_zones)
 296
 297 /**
 298  * for_each_pgdat - helper macro to iterate over all nodes
 299  * @pgdat - pointer to a pg_data_t variable
 300  *
 301  * Meant to help with common loops of the form
 302  * pgdat = pgdat_list;
 303  * while(pgdat) {
 304  *      ...
 305  *      pgdat = pgdat->pgdat_next;
 306  * }
 307  */
 308 #define for_each_pgdat(pgdat) \
 309         for (pgdat = pgdat_list; pgdat; pgdat = pgdat->pgdat_next)
 310
 311 /*
 312  * next_zone - helper magic for for_each_zone()
 313  * Thanks to William Lee Irwin III for this piece of ingenuity.
 314  */
 315 static inline struct zone *next_zone(struct zone *zone)
 316 {
 317         pg_data_t *pgdat = zone->zone_pgdat;
 318
 319         if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
 320                 zone++;
 321         else if (pgdat->pgdat_next) {
 322                 pgdat = pgdat->pgdat_next;
 323                 zone = pgdat->node_zones;
 324         } else
 325                 zone = NULL;
 326
 327         return zone;
 328 }
 329
 330 /**
 331  * for_each_zone - helper macro to iterate over all memory zones
 332  * @zone - pointer to struct zone variable
 333  *
 334  * The user only needs to declare the zone variable, for_each_zone
 335  * fills it in. This basically means for_each_zone() is an
 336  * easier to read version of this piece of code:
 337  *
 338  * for (pgdat = pgdat_list; pgdat; pgdat = pgdat->node_next)
 339  *      for (i = 0; i < MAX_NR_ZONES; ++i) {
 340  *              struct zone * z = pgdat->node_zones + i;
 341  *              ...
 342  *      }
 343  * }
 344  */
 345 #define for_each_zone(zone) \
 346         for (zone = pgdat_list->node_zones; zone; zone = next_zone(zone))
 347
 348 static inline int is_highmem_idx(int idx)
 349 {
 350         return (idx == ZONE_HIGHMEM);
 351 }
 352
 353 static inline int is_normal_idx(int idx)
 354 {
 355         return (idx == ZONE_NORMAL);
 356 }
 357 /**
 358  * is_highmem - helper function to quickly check if a struct zone is a
 359  *              highmem zone or not.  This is an attempt to keep references
 360  *              to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum.
 361  * @zone - pointer to struct zone variable
 362  */
 363 static inline int is_highmem(struct zone *zone)
 364 {
 365         return zone == zone->zone_pgdat->node_zones + ZONE_HIGHMEM;
 366 }
 367
 368 static inline int is_normal(struct zone *zone)
 369 {
 370         return zone == zone->zone_pgdat->node_zones + ZONE_NORMAL;
 371 }
 372
 373 /* These two functions are used to setup the per zone pages min values */
 374 struct ctl_table;
 375 struct file;
 376 int min_free_kbytes_sysctl_handler(struct ctl_table *, int, struct file *,
 377                                         void __user *, size_t *, loff_t *);
 378 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
 379 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int, struct file *,
 380                                         void __user *, size_t *, loff_t *);
 381
 382 #include <linux/topology.h>
 383 /* Returns the number of the current Node. */
 384 #define numa_node_id()          (cpu_to_node(_smp_processor_id()))
 385
 386 #ifndef CONFIG_DISCONTIGMEM
 387
 388 extern struct pglist_data contig_page_data;
 389 #define NODE_DATA(nid)          (&contig_page_data)
 390 #define NODE_MEM_MAP(nid)       mem_map
 391 #define MAX_NODES_SHIFT         1
 392 #define pfn_to_nid(pfn)         (0)
 393
 394 #else /* CONFIG_DISCONTIGMEM */
 395
 396 #include <asm/mmzone.h>
 397
 398 #if BITS_PER_LONG == 32 || defined(ARCH_HAS_ATOMIC_UNSIGNED)
 399 /*
 400  * with 32 bit page->flags field, we reserve 8 bits for node/zone info.
 401  * there are 3 zones (2 bits) and this leaves 8-2=6 bits for nodes.
 402  */
 403 #define MAX_NODES_SHIFT         6
 404 #elif BITS_PER_LONG == 64
 405 /*
 406  * with 64 bit flags field, there's plenty of room.
 407  */
 408 #define MAX_NODES_SHIFT         10
 409 #endif
 410
 411 #endif /* !CONFIG_DISCONTIGMEM */
 412
 413 #if NODES_SHIFT > MAX_NODES_SHIFT
 414 #error NODES_SHIFT > MAX_NODES_SHIFT
 415 #endif
 416
 417 /* There are currently 3 zones: DMA, Normal & Highmem, thus we need 2 bits */
 418 #define MAX_ZONES_SHIFT         2
 419
 420 #if ZONES_SHIFT > MAX_ZONES_SHIFT
 421 #error ZONES_SHIFT > MAX_ZONES_SHIFT
 422 #endif
 423
 424 #endif /* !__ASSEMBLY__ */
 425 #endif /* __KERNEL__ */
 426 #endif /* _LINUX_MMZONE_H */