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0231606785
There was lots of #ifdef noise in the kernel due to hotcpu_notifier(fn, prio) not correctly marking 'fn' as used in the !HOTPLUG_CPU case, and thus generating compiler warnings of unused symbols, hence forcing people to add #ifdefs. the compiler can skip truly unused functions just fine: text data bss dec hex filename 1624412 728710 3674856 6027978 5bfaca vmlinux.before 1624412 728710 3674856 6027978 5bfaca vmlinux.after [akpm@osdl.org: topology.c fix] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
521 lines
12 KiB
C
521 lines
12 KiB
C
/*
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* linux/mm/swap.c
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*
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*/
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/*
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* This file contains the default values for the opereation of the
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* Linux VM subsystem. Fine-tuning documentation can be found in
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* Documentation/sysctl/vm.txt.
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* Started 18.12.91
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* Swap aging added 23.2.95, Stephen Tweedie.
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* Buffermem limits added 12.3.98, Rik van Riel.
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*/
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/kernel_stat.h>
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#include <linux/swap.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/pagevec.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/mm_inline.h>
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#include <linux/buffer_head.h> /* for try_to_release_page() */
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#include <linux/module.h>
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#include <linux/percpu_counter.h>
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#include <linux/percpu.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/init.h>
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/* How many pages do we try to swap or page in/out together? */
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int page_cluster;
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/*
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* This path almost never happens for VM activity - pages are normally
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* freed via pagevecs. But it gets used by networking.
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*/
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static void fastcall __page_cache_release(struct page *page)
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{
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if (PageLRU(page)) {
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unsigned long flags;
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struct zone *zone = page_zone(page);
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spin_lock_irqsave(&zone->lru_lock, flags);
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VM_BUG_ON(!PageLRU(page));
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__ClearPageLRU(page);
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del_page_from_lru(zone, page);
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spin_unlock_irqrestore(&zone->lru_lock, flags);
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}
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free_hot_page(page);
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}
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static void put_compound_page(struct page *page)
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{
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page = (struct page *)page_private(page);
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if (put_page_testzero(page)) {
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compound_page_dtor *dtor;
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dtor = get_compound_page_dtor(page);
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(*dtor)(page);
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}
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}
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void put_page(struct page *page)
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{
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if (unlikely(PageCompound(page)))
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put_compound_page(page);
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else if (put_page_testzero(page))
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__page_cache_release(page);
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}
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EXPORT_SYMBOL(put_page);
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/**
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* put_pages_list(): release a list of pages
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*
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* Release a list of pages which are strung together on page.lru. Currently
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* used by read_cache_pages() and related error recovery code.
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*
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* @pages: list of pages threaded on page->lru
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*/
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void put_pages_list(struct list_head *pages)
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{
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while (!list_empty(pages)) {
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struct page *victim;
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victim = list_entry(pages->prev, struct page, lru);
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list_del(&victim->lru);
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page_cache_release(victim);
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}
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}
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EXPORT_SYMBOL(put_pages_list);
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/*
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* Writeback is about to end against a page which has been marked for immediate
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* reclaim. If it still appears to be reclaimable, move it to the tail of the
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* inactive list. The page still has PageWriteback set, which will pin it.
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*
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* We don't expect many pages to come through here, so don't bother batching
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* things up.
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*
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* To avoid placing the page at the tail of the LRU while PG_writeback is still
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* set, this function will clear PG_writeback before performing the page
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* motion. Do that inside the lru lock because once PG_writeback is cleared
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* we may not touch the page.
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*
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* Returns zero if it cleared PG_writeback.
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*/
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int rotate_reclaimable_page(struct page *page)
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{
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struct zone *zone;
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unsigned long flags;
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if (PageLocked(page))
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return 1;
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if (PageDirty(page))
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return 1;
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if (PageActive(page))
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return 1;
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if (!PageLRU(page))
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return 1;
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zone = page_zone(page);
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spin_lock_irqsave(&zone->lru_lock, flags);
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if (PageLRU(page) && !PageActive(page)) {
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list_move_tail(&page->lru, &zone->inactive_list);
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__count_vm_event(PGROTATED);
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}
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if (!test_clear_page_writeback(page))
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BUG();
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spin_unlock_irqrestore(&zone->lru_lock, flags);
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return 0;
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}
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/*
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* FIXME: speed this up?
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*/
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void fastcall activate_page(struct page *page)
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{
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struct zone *zone = page_zone(page);
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spin_lock_irq(&zone->lru_lock);
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if (PageLRU(page) && !PageActive(page)) {
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del_page_from_inactive_list(zone, page);
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SetPageActive(page);
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add_page_to_active_list(zone, page);
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__count_vm_event(PGACTIVATE);
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}
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spin_unlock_irq(&zone->lru_lock);
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}
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/*
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* Mark a page as having seen activity.
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*
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* inactive,unreferenced -> inactive,referenced
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* inactive,referenced -> active,unreferenced
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* active,unreferenced -> active,referenced
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*/
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void fastcall mark_page_accessed(struct page *page)
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{
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if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
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activate_page(page);
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ClearPageReferenced(page);
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} else if (!PageReferenced(page)) {
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SetPageReferenced(page);
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}
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}
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EXPORT_SYMBOL(mark_page_accessed);
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/**
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* lru_cache_add: add a page to the page lists
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* @page: the page to add
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*/
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static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
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static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
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void fastcall lru_cache_add(struct page *page)
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{
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struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
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page_cache_get(page);
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if (!pagevec_add(pvec, page))
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__pagevec_lru_add(pvec);
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put_cpu_var(lru_add_pvecs);
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}
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void fastcall lru_cache_add_active(struct page *page)
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{
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struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
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page_cache_get(page);
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if (!pagevec_add(pvec, page))
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__pagevec_lru_add_active(pvec);
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put_cpu_var(lru_add_active_pvecs);
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}
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static void __lru_add_drain(int cpu)
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{
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struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
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/* CPU is dead, so no locking needed. */
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if (pagevec_count(pvec))
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__pagevec_lru_add(pvec);
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pvec = &per_cpu(lru_add_active_pvecs, cpu);
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if (pagevec_count(pvec))
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__pagevec_lru_add_active(pvec);
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}
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void lru_add_drain(void)
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{
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__lru_add_drain(get_cpu());
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put_cpu();
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}
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#ifdef CONFIG_NUMA
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static void lru_add_drain_per_cpu(struct work_struct *dummy)
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{
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lru_add_drain();
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}
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/*
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* Returns 0 for success
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*/
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int lru_add_drain_all(void)
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{
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return schedule_on_each_cpu(lru_add_drain_per_cpu);
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}
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#else
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/*
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* Returns 0 for success
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*/
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int lru_add_drain_all(void)
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{
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lru_add_drain();
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return 0;
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}
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#endif
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/*
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* Batched page_cache_release(). Decrement the reference count on all the
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* passed pages. If it fell to zero then remove the page from the LRU and
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* free it.
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*
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* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
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* for the remainder of the operation.
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*
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* The locking in this function is against shrink_cache(): we recheck the
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* page count inside the lock to see whether shrink_cache grabbed the page
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* via the LRU. If it did, give up: shrink_cache will free it.
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*/
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void release_pages(struct page **pages, int nr, int cold)
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{
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int i;
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struct pagevec pages_to_free;
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struct zone *zone = NULL;
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pagevec_init(&pages_to_free, cold);
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for (i = 0; i < nr; i++) {
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struct page *page = pages[i];
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if (unlikely(PageCompound(page))) {
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if (zone) {
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spin_unlock_irq(&zone->lru_lock);
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zone = NULL;
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}
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put_compound_page(page);
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continue;
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}
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if (!put_page_testzero(page))
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continue;
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if (PageLRU(page)) {
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struct zone *pagezone = page_zone(page);
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if (pagezone != zone) {
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if (zone)
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spin_unlock_irq(&zone->lru_lock);
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zone = pagezone;
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spin_lock_irq(&zone->lru_lock);
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}
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VM_BUG_ON(!PageLRU(page));
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__ClearPageLRU(page);
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del_page_from_lru(zone, page);
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}
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if (!pagevec_add(&pages_to_free, page)) {
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if (zone) {
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spin_unlock_irq(&zone->lru_lock);
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zone = NULL;
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}
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__pagevec_free(&pages_to_free);
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pagevec_reinit(&pages_to_free);
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}
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}
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if (zone)
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spin_unlock_irq(&zone->lru_lock);
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pagevec_free(&pages_to_free);
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}
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/*
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* The pages which we're about to release may be in the deferred lru-addition
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* queues. That would prevent them from really being freed right now. That's
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* OK from a correctness point of view but is inefficient - those pages may be
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* cache-warm and we want to give them back to the page allocator ASAP.
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*
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* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
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* and __pagevec_lru_add_active() call release_pages() directly to avoid
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* mutual recursion.
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*/
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void __pagevec_release(struct pagevec *pvec)
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{
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lru_add_drain();
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release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
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pagevec_reinit(pvec);
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}
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EXPORT_SYMBOL(__pagevec_release);
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/*
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* pagevec_release() for pages which are known to not be on the LRU
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*
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* This function reinitialises the caller's pagevec.
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*/
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void __pagevec_release_nonlru(struct pagevec *pvec)
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{
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int i;
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struct pagevec pages_to_free;
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pagevec_init(&pages_to_free, pvec->cold);
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for (i = 0; i < pagevec_count(pvec); i++) {
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struct page *page = pvec->pages[i];
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VM_BUG_ON(PageLRU(page));
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if (put_page_testzero(page))
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pagevec_add(&pages_to_free, page);
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}
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pagevec_free(&pages_to_free);
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pagevec_reinit(pvec);
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}
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/*
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* Add the passed pages to the LRU, then drop the caller's refcount
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* on them. Reinitialises the caller's pagevec.
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*/
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void __pagevec_lru_add(struct pagevec *pvec)
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{
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int i;
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struct zone *zone = NULL;
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for (i = 0; i < pagevec_count(pvec); i++) {
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struct page *page = pvec->pages[i];
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struct zone *pagezone = page_zone(page);
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if (pagezone != zone) {
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if (zone)
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spin_unlock_irq(&zone->lru_lock);
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zone = pagezone;
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spin_lock_irq(&zone->lru_lock);
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}
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VM_BUG_ON(PageLRU(page));
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SetPageLRU(page);
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add_page_to_inactive_list(zone, page);
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}
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if (zone)
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spin_unlock_irq(&zone->lru_lock);
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release_pages(pvec->pages, pvec->nr, pvec->cold);
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pagevec_reinit(pvec);
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}
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EXPORT_SYMBOL(__pagevec_lru_add);
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void __pagevec_lru_add_active(struct pagevec *pvec)
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{
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int i;
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struct zone *zone = NULL;
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for (i = 0; i < pagevec_count(pvec); i++) {
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struct page *page = pvec->pages[i];
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struct zone *pagezone = page_zone(page);
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if (pagezone != zone) {
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if (zone)
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spin_unlock_irq(&zone->lru_lock);
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zone = pagezone;
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spin_lock_irq(&zone->lru_lock);
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}
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VM_BUG_ON(PageLRU(page));
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SetPageLRU(page);
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VM_BUG_ON(PageActive(page));
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SetPageActive(page);
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add_page_to_active_list(zone, page);
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}
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if (zone)
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spin_unlock_irq(&zone->lru_lock);
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release_pages(pvec->pages, pvec->nr, pvec->cold);
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pagevec_reinit(pvec);
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}
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/*
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* Try to drop buffers from the pages in a pagevec
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*/
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void pagevec_strip(struct pagevec *pvec)
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{
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int i;
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for (i = 0; i < pagevec_count(pvec); i++) {
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struct page *page = pvec->pages[i];
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if (PagePrivate(page) && !TestSetPageLocked(page)) {
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if (PagePrivate(page))
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try_to_release_page(page, 0);
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unlock_page(page);
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}
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}
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}
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/**
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* pagevec_lookup - gang pagecache lookup
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* @pvec: Where the resulting pages are placed
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* @mapping: The address_space to search
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* @start: The starting page index
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* @nr_pages: The maximum number of pages
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*
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* pagevec_lookup() will search for and return a group of up to @nr_pages pages
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* in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
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* reference against the pages in @pvec.
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*
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* The search returns a group of mapping-contiguous pages with ascending
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* indexes. There may be holes in the indices due to not-present pages.
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*
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* pagevec_lookup() returns the number of pages which were found.
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*/
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unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
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pgoff_t start, unsigned nr_pages)
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{
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pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
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return pagevec_count(pvec);
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}
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EXPORT_SYMBOL(pagevec_lookup);
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unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
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pgoff_t *index, int tag, unsigned nr_pages)
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{
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pvec->nr = find_get_pages_tag(mapping, index, tag,
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nr_pages, pvec->pages);
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return pagevec_count(pvec);
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}
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EXPORT_SYMBOL(pagevec_lookup_tag);
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#ifdef CONFIG_SMP
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/*
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* We tolerate a little inaccuracy to avoid ping-ponging the counter between
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* CPUs
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*/
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#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
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static DEFINE_PER_CPU(long, committed_space) = 0;
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void vm_acct_memory(long pages)
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{
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long *local;
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preempt_disable();
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local = &__get_cpu_var(committed_space);
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*local += pages;
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if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) {
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atomic_add(*local, &vm_committed_space);
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*local = 0;
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}
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preempt_enable();
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}
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#ifdef CONFIG_HOTPLUG_CPU
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/* Drop the CPU's cached committed space back into the central pool. */
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static int cpu_swap_callback(struct notifier_block *nfb,
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unsigned long action,
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void *hcpu)
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{
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long *committed;
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committed = &per_cpu(committed_space, (long)hcpu);
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if (action == CPU_DEAD) {
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atomic_add(*committed, &vm_committed_space);
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*committed = 0;
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__lru_add_drain((long)hcpu);
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}
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return NOTIFY_OK;
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}
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#endif /* CONFIG_HOTPLUG_CPU */
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#endif /* CONFIG_SMP */
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/*
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* Perform any setup for the swap system
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*/
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void __init swap_setup(void)
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{
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unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
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/* Use a smaller cluster for small-memory machines */
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if (megs < 16)
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page_cluster = 2;
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else
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page_cluster = 3;
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/*
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* Right now other parts of the system means that we
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* _really_ don't want to cluster much more
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*/
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#ifdef CONFIG_HOTPLUG_CPU
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hotcpu_notifier(cpu_swap_callback, 0);
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#endif
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}
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