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#ifndef _LINUX_SWAP_H
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#define _LINUX_SWAP_H
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#include <linux/spinlock.h>
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#include <linux/linkage.h>
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#include <linux/mmzone.h>
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#include <linux/list.h>
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#include <linux/sched.h>
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#include <asm/atomic.h>
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#include <asm/page.h>
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#define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
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#define SWAP_FLAG_PRIO_MASK 0x7fff
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#define SWAP_FLAG_PRIO_SHIFT 0
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static inline int current_is_kswapd(void)
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{
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return current->flags & PF_KSWAPD;
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}
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/*
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* MAX_SWAPFILES defines the maximum number of swaptypes: things which can
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* be swapped to. The swap type and the offset into that swap type are
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* encoded into pte's and into pgoff_t's in the swapcache. Using five bits
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* for the type means that the maximum number of swapcache pages is 27 bits
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* on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
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* the type/offset into the pte as 5/27 as well.
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*/
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#define MAX_SWAPFILES_SHIFT 5
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#define MAX_SWAPFILES (1 << MAX_SWAPFILES_SHIFT)
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/*
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* Magic header for a swap area. The first part of the union is
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* what the swap magic looks like for the old (limited to 128MB)
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* swap area format, the second part of the union adds - in the
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* old reserved area - some extra information. Note that the first
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* kilobyte is reserved for boot loader or disk label stuff...
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*
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* Having the magic at the end of the PAGE_SIZE makes detecting swap
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* areas somewhat tricky on machines that support multiple page sizes.
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* For 2.5 we'll probably want to move the magic to just beyond the
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* bootbits...
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*/
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union swap_header {
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struct {
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char reserved[PAGE_SIZE - 10];
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char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
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} magic;
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struct {
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char bootbits[1024]; /* Space for disklabel etc. */
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unsigned int version;
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unsigned int last_page;
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unsigned int nr_badpages;
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unsigned int padding[125];
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unsigned int badpages[1];
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} info;
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};
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/* A swap entry has to fit into a "unsigned long", as
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* the entry is hidden in the "index" field of the
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* swapper address space.
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*/
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typedef struct {
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unsigned long val;
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} swp_entry_t;
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/*
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* current->reclaim_state points to one of these when a task is running
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* memory reclaim
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*/
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struct reclaim_state {
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unsigned long reclaimed_slab;
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};
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#ifdef __KERNEL__
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struct address_space;
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struct sysinfo;
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struct writeback_control;
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struct zone;
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/*
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* A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
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* disk blocks. A list of swap extents maps the entire swapfile. (Where the
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* term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
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* from setup, they're handled identically.
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*
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* We always assume that blocks are of size PAGE_SIZE.
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*/
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struct swap_extent {
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struct list_head list;
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pgoff_t start_page;
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pgoff_t nr_pages;
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sector_t start_block;
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};
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/*
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* Max bad pages in the new format..
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*/
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#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
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#define MAX_SWAP_BADPAGES \
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((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
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enum {
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SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
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SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
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SWP_ACTIVE = (SWP_USED | SWP_WRITEOK),
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[PATCH] swap: scan_swap_map drop swap_device_lock
get_swap_page has often shown up on latency traces, doing lengthy scans while
holding two spinlocks. swap_list_lock is already dropped, now scan_swap_map
drop swap_device_lock before scanning the swap_map.
While scanning for an empty cluster, don't worry that racing tasks may
allocate what was free and free what was allocated; but when allocating an
entry, check it's still free after retaking the lock. Avoid dropping the lock
in the expected common path. No barriers beyond the locks, just let the
cookie crumble; highest_bit limit is volatile, but benign.
Guard against swapoff: must check SWP_WRITEOK before allocating, must raise
SWP_SCANNING reference count while in scan_swap_map, swapoff wait for that to
fall - just use schedule_timeout, we don't want to burden scan_swap_map
itself, and it's very unlikely that anyone can really still be in
scan_swap_map once swapoff gets this far.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
20 years ago
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/* add others here before... */
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SWP_SCANNING = (1 << 8), /* refcount in scan_swap_map */
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};
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#define SWAP_CLUSTER_MAX 32
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#define SWAP_MAP_MAX 0x7fff
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#define SWAP_MAP_BAD 0x8000
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/*
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* The in-memory structure used to track swap areas.
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*/
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struct swap_info_struct {
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unsigned int flags;
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[PATCH] swap: swap_lock replace list+device
The idea of a swap_device_lock per device, and a swap_list_lock over them all,
is appealing; but in practice almost every holder of swap_device_lock must
already hold swap_list_lock, which defeats the purpose of the split.
The only exceptions have been swap_duplicate, valid_swaphandles and an
untrodden path in try_to_unuse (plus a few places added in this series).
valid_swaphandles doesn't show up high in profiles, but swap_duplicate does
demand attention. However, with the hold time in get_swap_pages so much
reduced, I've not yet found a load and set of swap device priorities to show
even swap_duplicate benefitting from the split. Certainly the split is mere
overhead in the common case of a single swap device.
So, replace swap_list_lock and swap_device_lock by spinlock_t swap_lock
(generally we seem to prefer an _ in the name, and not hide in a macro).
If someone can show a regression in swap_duplicate, then probably we should
add a hashlock for the swap_map entries alone (shorts being anatomic), so as
to help the case of the single swap device too.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
20 years ago
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int prio; /* swap priority */
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struct file *swap_file;
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struct block_device *bdev;
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struct list_head extent_list;
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struct swap_extent *curr_swap_extent;
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unsigned old_block_size;
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unsigned short * swap_map;
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unsigned int lowest_bit;
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unsigned int highest_bit;
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unsigned int cluster_next;
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unsigned int cluster_nr;
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unsigned int pages;
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unsigned int max;
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unsigned int inuse_pages;
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int next; /* next entry on swap list */
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};
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struct swap_list_t {
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int head; /* head of priority-ordered swapfile list */
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int next; /* swapfile to be used next */
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};
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/* Swap 50% full? Release swapcache more aggressively.. */
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#define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
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/* linux/mm/oom_kill.c */
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extern void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order);
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/* linux/mm/memory.c */
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extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
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/* linux/mm/page_alloc.c */
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extern unsigned long totalram_pages;
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extern unsigned long totalhigh_pages;
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extern unsigned long totalreserve_pages;
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extern long nr_swap_pages;
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extern unsigned int nr_free_pages(void);
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extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat);
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extern unsigned int nr_free_buffer_pages(void);
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extern unsigned int nr_free_pagecache_pages(void);
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/* linux/mm/swap.c */
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extern void FASTCALL(lru_cache_add(struct page *));
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extern void FASTCALL(lru_cache_add_active(struct page *));
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extern void FASTCALL(activate_page(struct page *));
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extern void FASTCALL(mark_page_accessed(struct page *));
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extern void lru_add_drain(void);
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extern int lru_add_drain_all(void);
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extern int rotate_reclaimable_page(struct page *page);
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extern void swap_setup(void);
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/* linux/mm/vmscan.c */
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extern unsigned long try_to_free_pages(struct zone **, gfp_t);
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extern unsigned long shrink_all_memory(unsigned long nr_pages);
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extern int vm_swappiness;
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extern int remove_mapping(struct address_space *mapping, struct page *page);
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/* possible outcome of pageout() */
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typedef enum {
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/* failed to write page out, page is locked */
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PAGE_KEEP,
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/* move page to the active list, page is locked */
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PAGE_ACTIVATE,
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/* page has been sent to the disk successfully, page is unlocked */
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PAGE_SUCCESS,
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/* page is clean and locked */
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PAGE_CLEAN,
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} pageout_t;
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extern pageout_t pageout(struct page *page, struct address_space *mapping);
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#ifdef CONFIG_NUMA
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extern int zone_reclaim_mode;
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extern int zone_reclaim_interval;
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extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
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#else
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#define zone_reclaim_mode 0
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static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_MMU
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/* linux/mm/shmem.c */
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extern int shmem_unuse(swp_entry_t entry, struct page *page);
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#endif /* CONFIG_MMU */
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extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
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#ifdef CONFIG_SWAP
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/* linux/mm/page_io.c */
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extern int swap_readpage(struct file *, struct page *);
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extern int swap_writepage(struct page *page, struct writeback_control *wbc);
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extern int rw_swap_page_sync(int, swp_entry_t, struct page *);
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/* linux/mm/swap_state.c */
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extern struct address_space swapper_space;
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#define total_swapcache_pages swapper_space.nrpages
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extern void show_swap_cache_info(void);
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extern int add_to_swap(struct page *, gfp_t);
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extern void __delete_from_swap_cache(struct page *);
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extern void delete_from_swap_cache(struct page *);
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extern int move_to_swap_cache(struct page *, swp_entry_t);
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extern int move_from_swap_cache(struct page *, unsigned long,
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struct address_space *);
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extern void free_page_and_swap_cache(struct page *);
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extern void free_pages_and_swap_cache(struct page **, int);
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extern struct page * lookup_swap_cache(swp_entry_t);
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extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
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unsigned long addr);
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/* linux/mm/swapfile.c */
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extern long total_swap_pages;
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extern unsigned int nr_swapfiles;
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extern void si_swapinfo(struct sysinfo *);
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extern swp_entry_t get_swap_page(void);
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extern swp_entry_t get_swap_page_of_type(int);
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extern int swap_duplicate(swp_entry_t);
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extern int valid_swaphandles(swp_entry_t, unsigned long *);
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extern void swap_free(swp_entry_t);
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extern void free_swap_and_cache(swp_entry_t);
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extern int swap_type_of(dev_t);
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extern unsigned int count_swap_pages(int, int);
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extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
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extern struct swap_info_struct *get_swap_info_struct(unsigned);
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extern int can_share_swap_page(struct page *);
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extern int remove_exclusive_swap_page(struct page *);
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struct backing_dev_info;
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[PATCH] swap: swap_lock replace list+device
The idea of a swap_device_lock per device, and a swap_list_lock over them all,
is appealing; but in practice almost every holder of swap_device_lock must
already hold swap_list_lock, which defeats the purpose of the split.
The only exceptions have been swap_duplicate, valid_swaphandles and an
untrodden path in try_to_unuse (plus a few places added in this series).
valid_swaphandles doesn't show up high in profiles, but swap_duplicate does
demand attention. However, with the hold time in get_swap_pages so much
reduced, I've not yet found a load and set of swap device priorities to show
even swap_duplicate benefitting from the split. Certainly the split is mere
overhead in the common case of a single swap device.
So, replace swap_list_lock and swap_device_lock by spinlock_t swap_lock
(generally we seem to prefer an _ in the name, and not hide in a macro).
If someone can show a regression in swap_duplicate, then probably we should
add a hashlock for the swap_map entries alone (shorts being anatomic), so as
to help the case of the single swap device too.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
20 years ago
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extern spinlock_t swap_lock;
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extern int remove_vma_swap(struct vm_area_struct *vma, struct page *page);
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/* linux/mm/thrash.c */
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extern struct mm_struct * swap_token_mm;
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extern unsigned long swap_token_default_timeout;
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extern void grab_swap_token(void);
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extern void __put_swap_token(struct mm_struct *);
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static inline int has_swap_token(struct mm_struct *mm)
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{
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return (mm == swap_token_mm);
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}
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static inline void put_swap_token(struct mm_struct *mm)
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{
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if (has_swap_token(mm))
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__put_swap_token(mm);
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}
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static inline void disable_swap_token(void)
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{
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put_swap_token(swap_token_mm);
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}
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#else /* CONFIG_SWAP */
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#define total_swap_pages 0
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#define total_swapcache_pages 0UL
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#define si_swapinfo(val) \
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do { (val)->freeswap = (val)->totalswap = 0; } while (0)
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/* only sparc can not include linux/pagemap.h in this file
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* so leave page_cache_release and release_pages undeclared... */
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#define free_page_and_swap_cache(page) \
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page_cache_release(page)
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#define free_pages_and_swap_cache(pages, nr) \
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release_pages((pages), (nr), 0);
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#define show_swap_cache_info() /*NOTHING*/
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#define free_swap_and_cache(swp) /*NOTHING*/
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#define swap_duplicate(swp) /*NOTHING*/
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#define swap_free(swp) /*NOTHING*/
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#define read_swap_cache_async(swp,vma,addr) NULL
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#define lookup_swap_cache(swp) NULL
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#define valid_swaphandles(swp, off) 0
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#define can_share_swap_page(p) (page_mapcount(p) == 1)
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#define move_to_swap_cache(p, swp) 1
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#define move_from_swap_cache(p, i, m) 1
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#define __delete_from_swap_cache(p) /*NOTHING*/
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#define delete_from_swap_cache(p) /*NOTHING*/
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#define swap_token_default_timeout 0
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static inline int remove_exclusive_swap_page(struct page *p)
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{
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return 0;
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}
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static inline swp_entry_t get_swap_page(void)
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{
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swp_entry_t entry;
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entry.val = 0;
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return entry;
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}
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/* linux/mm/thrash.c */
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#define put_swap_token(x) do { } while(0)
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#define grab_swap_token() do { } while(0)
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#define has_swap_token(x) 0
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#define disable_swap_token() do { } while(0)
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#endif /* CONFIG_SWAP */
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#endif /* __KERNEL__*/
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#endif /* _LINUX_SWAP_H */
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