diff options
Diffstat (limited to 'vm/vm_page.c')
| -rw-r--r-- | vm/vm_page.c | 1244 |
1 files changed, 1241 insertions, 3 deletions
diff --git a/vm/vm_page.c b/vm/vm_page.c index f966e4dc..4c11ea7a 100644 --- a/vm/vm_page.c +++ b/vm/vm_page.c @@ -27,10 +27,13 @@ * multiprocessor systems. When a pool is empty and cannot provide a page, * it is filled by transferring multiple pages from the backend buddy system. * The symmetric case is handled likewise. + * + * TODO Limit number of dirty pages, block allocations above a top limit. */ #include <string.h> #include <kern/assert.h> +#include <kern/counters.h> #include <kern/cpu_number.h> #include <kern/debug.h> #include <kern/list.h> @@ -42,6 +45,7 @@ #include <machine/pmap.h> #include <sys/types.h> #include <vm/vm_page.h> +#include <vm/vm_pageout.h> #define DEBUG 0 @@ -100,12 +104,96 @@ struct vm_page_free_list { }; /* + * XXX Because of a potential deadlock involving the default pager (see + * vm_map_lock()), it's currently impossible to reliably determine the + * minimum number of free pages required for successful pageout. Since + * that process is dependent on the amount of physical memory, we scale + * the minimum number of free pages from it, in the hope that memory + * exhaustion happens as rarely as possible... + */ + +/* + * Ratio used to compute the minimum number of pages in a segment. + */ +#define VM_PAGE_SEG_THRESHOLD_MIN_NUM 5 +#define VM_PAGE_SEG_THRESHOLD_MIN_DENOM 100 + +/* + * Number of pages reserved for privileged allocations in a segment. + */ +#define VM_PAGE_SEG_THRESHOLD_MIN 500 + +/* + * Ratio used to compute the threshold below which pageout is started. + */ +#define VM_PAGE_SEG_THRESHOLD_LOW_NUM 6 +#define VM_PAGE_SEG_THRESHOLD_LOW_DENOM 100 + +/* + * Minimum value the low threshold can have for a segment. + */ +#define VM_PAGE_SEG_THRESHOLD_LOW 600 + +#if VM_PAGE_SEG_THRESHOLD_LOW <= VM_PAGE_SEG_THRESHOLD_MIN +#error VM_PAGE_SEG_THRESHOLD_LOW invalid +#endif /* VM_PAGE_SEG_THRESHOLD_LOW >= VM_PAGE_SEG_THRESHOLD_MIN */ + +/* + * Ratio used to compute the threshold above which pageout is stopped. + */ +#define VM_PAGE_SEG_THRESHOLD_HIGH_NUM 10 +#define VM_PAGE_SEG_THRESHOLD_HIGH_DENOM 100 + +/* + * Minimum value the high threshold can have for a segment. + */ +#define VM_PAGE_SEG_THRESHOLD_HIGH 1000 + +#if VM_PAGE_SEG_THRESHOLD_HIGH <= VM_PAGE_SEG_THRESHOLD_LOW +#error VM_PAGE_SEG_THRESHOLD_HIGH invalid +#endif /* VM_PAGE_SEG_THRESHOLD_HIGH <= VM_PAGE_SEG_THRESHOLD_LOW */ + +/* + * Minimum number of pages allowed for a segment. + */ +#define VM_PAGE_SEG_MIN_PAGES 2000 + +#if VM_PAGE_SEG_MIN_PAGES <= VM_PAGE_SEG_THRESHOLD_HIGH +#error VM_PAGE_SEG_MIN_PAGES invalid +#endif /* VM_PAGE_SEG_MIN_PAGES <= VM_PAGE_SEG_THRESHOLD_HIGH */ + +/* + * Ratio used to compute the threshold of active pages beyond which + * to refill the inactive queue. + */ +#define VM_PAGE_HIGH_ACTIVE_PAGE_NUM 1 +#define VM_PAGE_HIGH_ACTIVE_PAGE_DENOM 3 + +/* + * Page cache queue. + * + * XXX The current implementation hardcodes a preference to evict external + * pages first and keep internal ones as much as possible. This is because + * the Hurd default pager implementation suffers from bugs that can easily + * cause the system to freeze. + */ +struct vm_page_queue { + struct list internal_pages; + struct list external_pages; +}; + +/* * Segment name buffer size. */ #define VM_PAGE_NAME_SIZE 16 /* * Segment of contiguous memory. + * + * XXX Per-segment locking is probably useless, since one or both of the + * page queues lock and the free page queue lock is held on any access. + * However it should first be made clear which lock protects access to + * which members of a segment. */ struct vm_page_seg { struct vm_page_cpu_pool cpu_pools[NCPUS]; @@ -117,6 +205,19 @@ struct vm_page_seg { simple_lock_data_t lock; struct vm_page_free_list free_lists[VM_PAGE_NR_FREE_LISTS]; unsigned long nr_free_pages; + + /* Free memory thresholds */ + unsigned long min_free_pages; /* Privileged allocations only */ + unsigned long low_free_pages; /* Pageout daemon starts scanning */ + unsigned long high_free_pages; /* Pageout daemon stops scanning, + unprivileged allocations resume */ + + /* Page cache related data */ + struct vm_page_queue active_pages; + unsigned long nr_active_pages; + unsigned long high_active_pages; + struct vm_page_queue inactive_pages; + unsigned long nr_inactive_pages; }; /* @@ -160,6 +261,16 @@ static struct vm_page_boot_seg vm_page_boot_segs[VM_PAGE_MAX_SEGS] __initdata; */ static unsigned int vm_page_segs_size __read_mostly; +/* + * If true, unprivileged allocations are blocked, disregarding any other + * condition. + * + * This variable is also used to resume clients once pages are available. + * + * The free page queue lock must be held when accessing this variable. + */ +static boolean_t vm_page_alloc_paused; + static void __init vm_page_init_pa(struct vm_page *page, unsigned short seg_index, phys_addr_t pa) { @@ -183,6 +294,40 @@ vm_page_set_type(struct vm_page *page, unsigned int order, unsigned short type) page[i].type = type; } +static boolean_t +vm_page_pageable(const struct vm_page *page) +{ + return (page->object != NULL) + && (page->wire_count == 0) + && (page->active || page->inactive); +} + +static boolean_t +vm_page_can_move(const struct vm_page *page) +{ + /* + * This function is called on pages pulled from the page queues, + * implying they're pageable, which is why the wire count isn't + * checked here. + */ + + return !page->busy + && !page->wanted + && !page->absent + && page->object->alive; +} + +static void +vm_page_remove_mappings(struct vm_page *page) +{ + page->busy = TRUE; + pmap_page_protect(page->phys_addr, VM_PROT_NONE); + + if (!page->dirty) { + page->dirty = pmap_is_modified(page->phys_addr); + } +} + static void __init vm_page_free_list_init(struct vm_page_free_list *free_list) { @@ -219,6 +364,19 @@ vm_page_seg_alloc_from_buddy(struct vm_page_seg *seg, unsigned int order) assert(order < VM_PAGE_NR_FREE_LISTS); + if (vm_page_alloc_paused && current_thread() + && !current_thread()->vm_privilege) { + return NULL; + } else if (seg->nr_free_pages <= seg->low_free_pages) { + vm_pageout_start(); + + if ((seg->nr_free_pages <= seg->min_free_pages) + && current_thread() && !current_thread()->vm_privilege) { + vm_page_alloc_paused = TRUE; + return NULL; + } + } + for (i = order; i < VM_PAGE_NR_FREE_LISTS; i++) { free_list = &seg->free_lists[i]; @@ -241,6 +399,11 @@ vm_page_seg_alloc_from_buddy(struct vm_page_seg *seg, unsigned int order) } seg->nr_free_pages -= (1 << order); + + if (seg->nr_free_pages < seg->min_free_pages) { + vm_page_alloc_paused = TRUE; + } + return page; } @@ -364,6 +527,65 @@ vm_page_cpu_pool_drain(struct vm_page_cpu_pool *cpu_pool, simple_unlock(&seg->lock); } +static void +vm_page_queue_init(struct vm_page_queue *queue) +{ + list_init(&queue->internal_pages); + list_init(&queue->external_pages); +} + +static void +vm_page_queue_push(struct vm_page_queue *queue, struct vm_page *page) +{ + if (page->external) { + list_insert_tail(&queue->external_pages, &page->node); + } else { + list_insert_tail(&queue->internal_pages, &page->node); + } +} + +static void +vm_page_queue_remove(struct vm_page_queue *queue, struct vm_page *page) +{ + (void)queue; + list_remove(&page->node); +} + +static struct vm_page * +vm_page_queue_first(struct vm_page_queue *queue, boolean_t external_only) +{ + struct vm_page *page; + + if (!list_empty(&queue->external_pages)) { + page = list_first_entry(&queue->external_pages, struct vm_page, node); + return page; + } + + if (!external_only && !list_empty(&queue->internal_pages)) { + page = list_first_entry(&queue->internal_pages, struct vm_page, node); + return page; + } + + return NULL; +} + +static struct vm_page_seg * +vm_page_seg_get(unsigned short index) +{ + assert(index < vm_page_segs_size); + return &vm_page_segs[index]; +} + +static unsigned int +vm_page_seg_index(const struct vm_page_seg *seg) +{ + unsigned int index; + + index = seg - vm_page_segs; + assert(index < vm_page_segs_size); + return index; +} + static phys_addr_t __init vm_page_seg_size(struct vm_page_seg *seg) { @@ -386,6 +608,39 @@ vm_page_seg_compute_pool_size(struct vm_page_seg *seg) } static void __init +vm_page_seg_compute_pageout_thresholds(struct vm_page_seg *seg) +{ + unsigned long nr_pages; + + nr_pages = vm_page_atop(vm_page_seg_size(seg)); + + if (nr_pages < VM_PAGE_SEG_MIN_PAGES) { + panic("vm_page: segment too small"); + } + + seg->min_free_pages = nr_pages * VM_PAGE_SEG_THRESHOLD_MIN_NUM + / VM_PAGE_SEG_THRESHOLD_MIN_DENOM; + + if (seg->min_free_pages < VM_PAGE_SEG_THRESHOLD_MIN) { + seg->min_free_pages = VM_PAGE_SEG_THRESHOLD_MIN; + } + + seg->low_free_pages = nr_pages * VM_PAGE_SEG_THRESHOLD_LOW_NUM + / VM_PAGE_SEG_THRESHOLD_LOW_DENOM; + + if (seg->low_free_pages < VM_PAGE_SEG_THRESHOLD_LOW) { + seg->low_free_pages = VM_PAGE_SEG_THRESHOLD_LOW; + } + + seg->high_free_pages = nr_pages * VM_PAGE_SEG_THRESHOLD_HIGH_NUM + / VM_PAGE_SEG_THRESHOLD_HIGH_DENOM; + + if (seg->high_free_pages < VM_PAGE_SEG_THRESHOLD_HIGH) { + seg->high_free_pages = VM_PAGE_SEG_THRESHOLD_HIGH; + } +} + +static void __init vm_page_seg_init(struct vm_page_seg *seg, phys_addr_t start, phys_addr_t end, struct vm_page *pages) { @@ -408,7 +663,15 @@ vm_page_seg_init(struct vm_page_seg *seg, phys_addr_t start, phys_addr_t end, vm_page_free_list_init(&seg->free_lists[i]); seg->nr_free_pages = 0; - i = seg - vm_page_segs; + + vm_page_seg_compute_pageout_thresholds(seg); + + vm_page_queue_init(&seg->active_pages); + seg->nr_active_pages = 0; + vm_page_queue_init(&seg->inactive_pages); + seg->nr_inactive_pages = 0; + + i = vm_page_seg_index(seg); for (pa = seg->start; pa < seg->end; pa += PAGE_SIZE) vm_page_init_pa(&pages[vm_page_atop(pa - seg->start)], i, pa); @@ -485,6 +748,502 @@ vm_page_seg_free(struct vm_page_seg *seg, struct vm_page *page, } } +static void +vm_page_seg_add_active_page(struct vm_page_seg *seg, struct vm_page *page) +{ + assert(page->object != NULL); + assert(page->seg_index == vm_page_seg_index(seg)); + assert(page->type != VM_PT_FREE); + assert(page->order == VM_PAGE_ORDER_UNLISTED); + assert(!page->free && !page->active && !page->inactive); + page->active = TRUE; + page->reference = TRUE; + vm_page_queue_push(&seg->active_pages, page); + seg->nr_active_pages++; + vm_page_active_count++; +} + +static void +vm_page_seg_remove_active_page(struct vm_page_seg *seg, struct vm_page *page) +{ + assert(page->object != NULL); + assert(page->seg_index == vm_page_seg_index(seg)); + assert(page->type != VM_PT_FREE); + assert(page->order == VM_PAGE_ORDER_UNLISTED); + assert(!page->free && page->active && !page->inactive); + page->active = FALSE; + vm_page_queue_remove(&seg->active_pages, page); + seg->nr_active_pages--; + vm_page_active_count--; +} + +static void +vm_page_seg_add_inactive_page(struct vm_page_seg *seg, struct vm_page *page) +{ + assert(page->object != NULL); + assert(page->seg_index == vm_page_seg_index(seg)); + assert(page->type != VM_PT_FREE); + assert(page->order == VM_PAGE_ORDER_UNLISTED); + assert(!page->free && !page->active && !page->inactive); + page->inactive = TRUE; + vm_page_queue_push(&seg->inactive_pages, page); + seg->nr_inactive_pages++; + vm_page_inactive_count++; +} + +static void +vm_page_seg_remove_inactive_page(struct vm_page_seg *seg, struct vm_page *page) +{ + assert(page->object != NULL); + assert(page->seg_index == vm_page_seg_index(seg)); + assert(page->type != VM_PT_FREE); + assert(page->order == VM_PAGE_ORDER_UNLISTED); + assert(!page->free && !page->active && page->inactive); + page->inactive = FALSE; + vm_page_queue_remove(&seg->inactive_pages, page); + seg->nr_inactive_pages--; + vm_page_inactive_count--; +} + +/* + * Attempt to pull an active page. + * + * If successful, the object containing the page is locked. + */ +static struct vm_page * +vm_page_seg_pull_active_page(struct vm_page_seg *seg, boolean_t external_only) +{ + struct vm_page *page, *first; + boolean_t locked; + + first = NULL; + + for (;;) { + page = vm_page_queue_first(&seg->active_pages, external_only); + + if (page == NULL) { + break; + } else if (first == NULL) { + first = page; + } else if (first == page) { + break; + } + + vm_page_seg_remove_active_page(seg, page); + locked = vm_object_lock_try(page->object); + + if (!locked) { + vm_page_seg_add_active_page(seg, page); + continue; + } + + if (!vm_page_can_move(page)) { + vm_page_seg_add_active_page(seg, page); + vm_object_unlock(page->object); + continue; + } + + return page; + } + + return NULL; +} + +/* + * Attempt to pull an inactive page. + * + * If successful, the object containing the page is locked. + * + * XXX See vm_page_seg_pull_active_page (duplicated code). + */ +static struct vm_page * +vm_page_seg_pull_inactive_page(struct vm_page_seg *seg, boolean_t external_only) +{ + struct vm_page *page, *first; + boolean_t locked; + + first = NULL; + + for (;;) { + page = vm_page_queue_first(&seg->inactive_pages, external_only); + + if (page == NULL) { + break; + } else if (first == NULL) { + first = page; + } else if (first == page) { + break; + } + + vm_page_seg_remove_inactive_page(seg, page); + locked = vm_object_lock_try(page->object); + + if (!locked) { + vm_page_seg_add_inactive_page(seg, page); + continue; + } + + if (!vm_page_can_move(page)) { + vm_page_seg_add_inactive_page(seg, page); + vm_object_unlock(page->object); + continue; + } + + return page; + } + + return NULL; +} + +/* + * Attempt to pull a page cache page. + * + * If successful, the object containing the page is locked. + */ +static struct vm_page * +vm_page_seg_pull_cache_page(struct vm_page_seg *seg, + boolean_t external_only, + boolean_t *was_active) +{ + struct vm_page *page; + + page = vm_page_seg_pull_inactive_page(seg, external_only); + + if (page != NULL) { + *was_active = FALSE; + return page; + } + + page = vm_page_seg_pull_active_page(seg, external_only); + + if (page != NULL) { + *was_active = TRUE; + return page; + } + + return NULL; +} + +static boolean_t +vm_page_seg_min_page_available(const struct vm_page_seg *seg) +{ + return (seg->nr_free_pages > seg->min_free_pages); +} + +static boolean_t +vm_page_seg_page_available(const struct vm_page_seg *seg) +{ + return (seg->nr_free_pages > seg->high_free_pages); +} + +static boolean_t +vm_page_seg_usable(const struct vm_page_seg *seg) +{ + return (seg->nr_free_pages >= seg->high_free_pages); +} + +static void +vm_page_seg_double_lock(struct vm_page_seg *seg1, struct vm_page_seg *seg2) +{ + assert(seg1 != seg2); + + if (seg1 < seg2) { + simple_lock(&seg1->lock); + simple_lock(&seg2->lock); + } else { + simple_lock(&seg2->lock); + simple_lock(&seg1->lock); + } +} + +static void +vm_page_seg_double_unlock(struct vm_page_seg *seg1, struct vm_page_seg *seg2) +{ + simple_unlock(&seg1->lock); + simple_unlock(&seg2->lock); +} + +/* + * Attempt to balance a segment by moving one page to another segment. + * + * Return TRUE if a page was actually moved. + */ +static boolean_t +vm_page_seg_balance_page(struct vm_page_seg *seg, + struct vm_page_seg *remote_seg) +{ + struct vm_page *src, *dest; + vm_object_t object; + vm_offset_t offset; + boolean_t was_active; + + vm_page_lock_queues(); + simple_lock(&vm_page_queue_free_lock); + vm_page_seg_double_lock(seg, remote_seg); + + if (vm_page_seg_usable(seg) + || !vm_page_seg_page_available(remote_seg)) { + goto error; + } + + src = vm_page_seg_pull_cache_page(seg, FALSE, &was_active); + + if (src == NULL) { + goto error; + } + + assert(src->object != NULL); + assert(!src->fictitious && !src->private); + assert(src->wire_count == 0); + assert(src->type != VM_PT_FREE); + assert(src->order == VM_PAGE_ORDER_UNLISTED); + + dest = vm_page_seg_alloc_from_buddy(remote_seg, 0); + assert(dest != NULL); + + vm_page_seg_double_unlock(seg, remote_seg); + simple_unlock(&vm_page_queue_free_lock); + + if (!was_active && !src->reference && pmap_is_referenced(src->phys_addr)) { + src->reference = TRUE; + } + + object = src->object; + offset = src->offset; + vm_page_remove(src); + + vm_page_remove_mappings(src); + + vm_page_set_type(dest, 0, src->type); + memcpy(&dest->vm_page_header, &src->vm_page_header, + sizeof(*dest) - VM_PAGE_HEADER_SIZE); + vm_page_copy(src, dest); + + if (!src->dirty) { + pmap_clear_modify(dest->phys_addr); + } + + dest->busy = FALSE; + + simple_lock(&vm_page_queue_free_lock); + vm_page_init(src); + src->free = TRUE; + simple_lock(&seg->lock); + vm_page_set_type(src, 0, VM_PT_FREE); + vm_page_seg_free_to_buddy(seg, src, 0); + simple_unlock(&seg->lock); + simple_unlock(&vm_page_queue_free_lock); + + vm_page_insert(dest, object, offset); + vm_object_unlock(object); + + if (was_active) { + vm_page_activate(dest); + } else { + vm_page_deactivate(dest); + } + + vm_page_unlock_queues(); + + return TRUE; + +error: + vm_page_seg_double_unlock(seg, remote_seg); + simple_unlock(&vm_page_queue_free_lock); + vm_page_unlock_queues(); + return FALSE; +} + +static boolean_t +vm_page_seg_balance(struct vm_page_seg *seg) +{ + struct vm_page_seg *remote_seg; + unsigned int i; + boolean_t balanced; + + /* + * It's important here that pages are moved to lower priority + * segments first. + */ + + for (i = vm_page_segs_size - 1; i < vm_page_segs_size; i--) { + remote_seg = vm_page_seg_get(i); + + if (remote_seg == seg) { + continue; + } + + balanced = vm_page_seg_balance_page(seg, remote_seg); + + if (balanced) { + return TRUE; + } + } + + return FALSE; +} + +static boolean_t +vm_page_seg_evict(struct vm_page_seg *seg, + boolean_t external_only, boolean_t low_memory) +{ + struct vm_page *page; + boolean_t reclaim, laundry; + vm_object_t object; + boolean_t was_active; + + page = NULL; + object = NULL; + +restart: + vm_page_lock_queues(); + simple_lock(&seg->lock); + + if (page != NULL) { + vm_object_lock(page->object); + } else { + page = vm_page_seg_pull_cache_page(seg, external_only, &was_active); + + if (page == NULL) { + goto out; + } + } + + assert(page->object != NULL); + assert(!page->fictitious && !page->private); + assert(page->wire_count == 0); + assert(page->type != VM_PT_FREE); + assert(page->order == VM_PAGE_ORDER_UNLISTED); + + object = page->object; + + if (!was_active + && (page->reference || pmap_is_referenced(page->phys_addr))) { + vm_page_seg_add_active_page(seg, page); + simple_unlock(&seg->lock); + vm_object_unlock(object); + vm_stat.reactivations++; + current_task()->reactivations++; + vm_page_unlock_queues(); + page = NULL; + goto restart; + } + + vm_page_remove_mappings(page); + + if (!page->dirty && !page->precious) { + reclaim = TRUE; + goto out; + } + + reclaim = FALSE; + + /* + * If we are very low on memory, then we can't rely on an external + * pager to clean a dirty page, because external pagers are not + * vm-privileged. + * + * The laundry bit tells vm_pageout_setup not to do any special + * processing of this page since it's immediately going to be + * double paged out to the default pager. The laundry bit is + * reset and the page is inserted into an internal object by + * vm_pageout_setup before the double paging pass. + */ + + assert(!page->laundry); + + if (object->internal || !low_memory) { + laundry = FALSE; + } else { + laundry = page->laundry = TRUE; + } + +out: + simple_unlock(&seg->lock); + + if (object == NULL) { + vm_page_unlock_queues(); + return FALSE; + } + + if (reclaim) { + vm_page_free(page); + vm_page_unlock_queues(); + + if (vm_object_collectable(object)) { + vm_object_collect(object); + } else { + vm_object_unlock(object); + } + + return TRUE; + } + + vm_page_unlock_queues(); + + /* + * If there is no memory object for the page, create one and hand it + * to the default pager. First try to collapse, so we don't create + * one unnecessarily. + */ + + if (!object->pager_initialized) { + vm_object_collapse(object); + } + + if (!object->pager_initialized) { + vm_object_pager_create(object); + } + + if (!object->pager_initialized) { + panic("vm_page_seg_evict"); + } + + vm_pageout_page(page, FALSE, TRUE); /* flush it */ + vm_object_unlock(object); + + if (laundry) { + goto restart; + } + + return TRUE; +} + +static void +vm_page_seg_compute_high_active_page(struct vm_page_seg *seg) +{ + unsigned long nr_pages; + + nr_pages = seg->nr_active_pages + seg->nr_inactive_pages; + seg->high_active_pages = nr_pages * VM_PAGE_HIGH_ACTIVE_PAGE_NUM + / VM_PAGE_HIGH_ACTIVE_PAGE_DENOM; +} + +static void +vm_page_seg_refill_inactive(struct vm_page_seg *seg) +{ + struct vm_page *page; + + simple_lock(&seg->lock); + + vm_page_seg_compute_high_active_page(seg); + + while (seg->nr_active_pages > seg->high_active_pages) { + page = vm_page_seg_pull_active_page(seg, FALSE); + + if (page == NULL) { + break; + } + + page->reference = FALSE; + pmap_clear_reference(page->phys_addr); + vm_page_seg_add_inactive_page(seg, page); + vm_object_unlock(page->object); + } + + simple_unlock(&seg->lock); +} + void __init vm_page_load(unsigned int seg_index, phys_addr_t start, phys_addr_t end) { @@ -712,6 +1471,77 @@ vm_page_lookup_pa(phys_addr_t pa) return NULL; } +static struct vm_page_seg * +vm_page_lookup_seg(const struct vm_page *page) +{ + struct vm_page_seg *seg; + unsigned int i; + + for (i = 0; i < vm_page_segs_size; i++) { + seg = &vm_page_segs[i]; + + if ((page->phys_addr >= seg->start) && (page->phys_addr < seg->end)) { + return seg; + } + } + + return NULL; +} + +void vm_page_check(const struct vm_page *page) +{ + if (page->fictitious) { + if (page->private) { + panic("vm_page: page both fictitious and private"); + } + + if (page->phys_addr != vm_page_fictitious_addr) { + panic("vm_page: invalid fictitious page"); + } + } else { + struct vm_page_seg *seg; + + if (page->phys_addr == vm_page_fictitious_addr) { + panic("vm_page: real page has fictitious address"); + } + + seg = vm_page_lookup_seg(page); + + if (seg == NULL) { + if (!page->private) { + panic("vm_page: page claims it's managed but not in any segment"); + } + } else { + if (page->private) { + struct vm_page *real_page; + + if (vm_page_pageable(page)) { + panic("vm_page: private page is pageable"); + } + + real_page = vm_page_lookup_pa(page->phys_addr); + + if (vm_page_pageable(real_page)) { + panic("vm_page: page underlying private page is pageable"); + } + + if ((real_page->type == VM_PT_FREE) + || (real_page->order != VM_PAGE_ORDER_UNLISTED)) { + panic("vm_page: page underlying private pagei is free"); + } + } else { + unsigned int index; + + index = vm_page_seg_index(seg); + + if (index != page->seg_index) { + panic("vm_page: page segment mismatch"); + } + } + } + } +} + struct vm_page * vm_page_alloc_pa(unsigned int order, unsigned int selector, unsigned short type) { @@ -725,8 +1555,8 @@ vm_page_alloc_pa(unsigned int order, unsigned int selector, unsigned short type) return page; } - if (type == VM_PT_PMAP) - panic("vm_page: unable to allocate pmap page"); + if (!current_thread() || current_thread()->vm_privilege) + panic("vm_page: privileged thread unable to allocate page"); return NULL; } @@ -769,6 +1599,9 @@ vm_page_info_all(void) printf("vm_page: %s: pages: %lu (%luM), free: %lu (%luM)\n", vm_page_seg_name(i), pages, pages >> (20 - PAGE_SHIFT), seg->nr_free_pages, seg->nr_free_pages >> (20 - PAGE_SHIFT)); + printf("vm_page: %s: min:%lu low:%lu high:%lu\n", + vm_page_seg_name(vm_page_seg_index(seg)), + seg->min_free_pages, seg->low_free_pages, seg->high_free_pages); } } @@ -879,3 +1712,408 @@ vm_page_mem_free(void) return total; } + +/* + * Mark this page as wired down by yet another map, removing it + * from paging queues as necessary. + * + * The page's object and the page queues must be locked. + */ +void +vm_page_wire(struct vm_page *page) +{ + VM_PAGE_CHECK(page); + + if (page->wire_count == 0) { + vm_page_queues_remove(page); + + if (!page->private && !page->fictitious) { + vm_page_wire_count++; + } + } + + page->wire_count++; +} + +/* + * Release one wiring of this page, potentially enabling it to be paged again. + * + * The page's object and the page queues must be locked. + */ +void +vm_page_unwire(struct vm_page *page) +{ + struct vm_page_seg *seg; + + VM_PAGE_CHECK(page); + + assert(page->wire_count != 0); + page->wire_count--; + + if ((page->wire_count != 0) + || page->fictitious + || page->private) { + return; + } + + seg = vm_page_seg_get(page->seg_index); + + simple_lock(&seg->lock); + vm_page_seg_add_active_page(seg, page); + simple_unlock(&seg->lock); + + vm_page_wire_count--; +} + +/* + * Returns the given page to the inactive list, indicating that + * no physical maps have access to this page. + * [Used by the physical mapping system.] + * + * The page queues must be locked. + */ +void +vm_page_deactivate(struct vm_page *page) +{ + struct vm_page_seg *seg; + + VM_PAGE_CHECK(page); + + /* + * This page is no longer very interesting. If it was + * interesting (active or inactive/referenced), then we + * clear the reference bit and (re)enter it in the + * inactive queue. Note wired pages should not have + * their reference bit cleared. + */ + + if (page->active || (page->inactive && page->reference)) { + if (!page->fictitious && !page->private && !page->absent) { + pmap_clear_reference(page->phys_addr); + } + + page->reference = FALSE; + vm_page_queues_remove(page); + } + + if ((page->wire_count == 0) && !page->fictitious + && !page->private && !page->inactive) { + seg = vm_page_seg_get(page->seg_index); + + simple_lock(&seg->lock); + vm_page_seg_add_inactive_page(seg, page); + simple_unlock(&seg->lock); + } +} + +/* + * Put the specified page on the active list (if appropriate). + * + * The page queues must be locked. + */ +void +vm_page_activate(struct vm_page *page) +{ + struct vm_page_seg *seg; + + VM_PAGE_CHECK(page); + + /* + * Unconditionally remove so that, even if the page was already + * active, it gets back to the end of the active queue. + */ + vm_page_queues_remove(page); + + if ((page->wire_count == 0) && !page->fictitious && !page->private) { + seg = vm_page_seg_get(page->seg_index); + + if (page->active) + panic("vm_page_activate: already active"); + + simple_lock(&seg->lock); + vm_page_seg_add_active_page(seg, page); + simple_unlock(&seg->lock); + } +} + +void +vm_page_queues_remove(struct vm_page *page) +{ + struct vm_page_seg *seg; + + assert(!page->active || !page->inactive); + + if (!page->active && !page->inactive) { + return; + } + + seg = vm_page_seg_get(page->seg_index); + + simple_lock(&seg->lock); + + if (page->active) { + vm_page_seg_remove_active_page(seg, page); + } else { + vm_page_seg_remove_inactive_page(seg, page); + } + + simple_unlock(&seg->lock); +} + +/* + * Check whether segments are all usable for unprivileged allocations. + * + * If all segments are usable, resume pending unprivileged allocations + * and return TRUE. + * + * This function acquires vm_page_queue_free_lock, which is held on return. + */ +static boolean_t +vm_page_check_usable(void) +{ + struct vm_page_seg *seg; + boolean_t usable; + unsigned int i; + + simple_lock(&vm_page_queue_free_lock); + + for (i = 0; i < vm_page_segs_size; i++) { + seg = vm_page_seg_get(i); + + simple_lock(&seg->lock); + usable = vm_page_seg_usable(seg); + simple_unlock(&seg->lock); + + if (!usable) { + return FALSE; + } + } + + vm_page_external_pagedout = -1; + vm_page_alloc_paused = FALSE; + thread_wakeup(&vm_page_alloc_paused); + return TRUE; +} + +static boolean_t +vm_page_may_balance(void) +{ + struct vm_page_seg *seg; + boolean_t page_available; + unsigned int i; + + for (i = 0; i < vm_page_segs_size; i++) { + seg = vm_page_seg_get(i); + + simple_lock(&seg->lock); + page_available = vm_page_seg_page_available(seg); + simple_unlock(&seg->lock); + + if (page_available) { + return TRUE; + } + } + + return FALSE; +} + +static boolean_t +vm_page_balance_once(void) +{ + boolean_t balanced; + unsigned int i; + + /* + * It's important here that pages are moved from higher priority + * segments first. + */ + + for (i = 0; i < vm_page_segs_size; i++) { + balanced = vm_page_seg_balance(vm_page_seg_get(i)); + + if (balanced) { + return TRUE; + } + } + + return FALSE; +} + +boolean_t +vm_page_balance(void) +{ + boolean_t balanced; + + while (vm_page_may_balance()) { + balanced = vm_page_balance_once(); + + if (!balanced) { + break; + } + } + + return vm_page_check_usable(); +} + +static boolean_t +vm_page_evict_once(boolean_t external_only) +{ + struct vm_page_seg *seg; + boolean_t low_memory, min_page_available, evicted; + unsigned int i; + + /* + * XXX Page allocation currently only uses the DIRECTMAP selector, + * allowing us to know which segments to look at when determining + * whether we're very low on memory. + */ + low_memory = TRUE; + + simple_lock(&vm_page_queue_free_lock); + + for (i = 0; i < vm_page_segs_size; i++) { + if (i > VM_PAGE_SEG_DIRECTMAP) { + break; + } + + seg = vm_page_seg_get(i); + + simple_lock(&seg->lock); + min_page_available = vm_page_seg_min_page_available(seg); + simple_unlock(&seg->lock); + + if (min_page_available) { + low_memory = FALSE; + break; + } + } + + simple_unlock(&vm_page_queue_free_lock); + + /* + * It's important here that pages are evicted from lower priority + * segments first. + */ + + for (i = vm_page_segs_size - 1; i < vm_page_segs_size; i--) { + evicted = vm_page_seg_evict(vm_page_seg_get(i), + external_only, low_memory); + + if (evicted) { + return TRUE; + } + } + + return FALSE; +} + +#define VM_PAGE_MAX_LAUNDRY 5 +#define VM_PAGE_MAX_EVICTIONS 5 + +boolean_t +vm_page_evict(boolean_t *should_wait) +{ + boolean_t pause, evicted, external_only; + unsigned int i; + + *should_wait = TRUE; + external_only = TRUE; + + simple_lock(&vm_page_queue_free_lock); + vm_page_external_pagedout = 0; + simple_unlock(&vm_page_queue_free_lock); + +again: + vm_page_lock_queues(); + pause = (vm_page_laundry_count >= VM_PAGE_MAX_LAUNDRY); + vm_page_unlock_queues(); + + if (pause) { + simple_lock(&vm_page_queue_free_lock); + return FALSE; + } + + for (i = 0; i < VM_PAGE_MAX_EVICTIONS; i++) { + evicted = vm_page_evict_once(external_only); + + if (!evicted) { + break; + } + } + + simple_lock(&vm_page_queue_free_lock); + + /* + * Keep in mind eviction may not cause pageouts, since non-precious + * clean pages are simply released. + */ + if ((vm_page_external_pagedout == 0) || (vm_page_laundry_count == 0)) { + /* + * No pageout, but some clean pages were freed. Start a complete + * scan again without waiting. + */ + if (evicted) { + *should_wait = FALSE; + return FALSE; + } + + /* + * Eviction failed, consider pages from internal objects on the + * next attempt. + */ + if (external_only) { + simple_unlock(&vm_page_queue_free_lock); + external_only = FALSE; + goto again; + } + + /* + * TODO Find out what could cause this and how to deal with it. + * This will likely require an out-of-memory killer. + */ + panic("vm_page: unable to recycle any page"); + } + + simple_unlock(&vm_page_queue_free_lock); + + return vm_page_check_usable(); +} + +void +vm_page_refill_inactive(void) +{ + unsigned int i; + + vm_page_lock_queues(); + + for (i = 0; i < vm_page_segs_size; i++) { + vm_page_seg_refill_inactive(vm_page_seg_get(i)); + } + + vm_page_unlock_queues(); +} + +void +vm_page_wait(void (*continuation)(void)) +{ + assert(!current_thread()->vm_privilege); + + simple_lock(&vm_page_queue_free_lock); + + if (!vm_page_alloc_paused) { + simple_unlock(&vm_page_queue_free_lock); + return; + } + + assert_wait(&vm_page_alloc_paused, FALSE); + + simple_unlock(&vm_page_queue_free_lock); + + if (continuation != 0) { + counter(c_vm_page_wait_block_user++); + thread_block(continuation); + } else { + counter(c_vm_page_wait_block_kernel++); + thread_block((void (*)(void)) 0); + } +} |