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33 * @(#)vmmeter.h 8.2 (Berkeley) 7/10/94
34 * $FreeBSD: src/sys/sys/vmmeter.h,v 1.21.2.2 2002/10/10 19:28:21 dillon Exp $
35 * $DragonFly: src/sys/vm/vm_page2.h,v 1.3 2008/04/14 20:00:29 dillon Exp $
38 #ifndef _VM_VM_PAGE2_H_
39 #define _VM_VM_PAGE2_H_
41 #ifndef _SYS_VMMETER_H_
42 #include <sys/vmmeter.h>
45 #include <sys/queue.h>
48 #include <vm/vm_page.h>
50 #ifndef _SYS_SPINLOCK_H_
51 #include <sys/spinlock.h>
53 #ifndef _SYS_SPINLOCK2_H_
54 #include <sys/spinlock2.h>
60 * Return TRUE if we are under our severe low-free-pages threshold
62 * This causes user processes to stall to avoid exhausting memory that
63 * the kernel might need.
65 * reserved < severe < minimum < target < paging_target
69 vm_page_count_severe(void)
71 return (vmstats.v_free_severe >
72 vmstats.v_free_count + vmstats.v_cache_count ||
73 vmstats.v_free_reserved > vmstats.v_free_count);
77 * Return TRUE if we are under our minimum low-free-pages threshold.
78 * This activates the pageout demon. The pageout demon tries to
79 * reach the target but may stop once it satisfies the minimum.
81 * reserved < severe < minimum < target < paging_target
85 vm_page_count_min(int donotcount)
87 return (vmstats.v_free_min + donotcount >
88 (vmstats.v_free_count + vmstats.v_cache_count) ||
89 vmstats.v_free_reserved > vmstats.v_free_count);
93 * Return TRUE if we are under our free page target. The pageout demon
94 * tries to reach the target but may stop once it gets past the min.
98 vm_page_count_target(void)
100 return (vmstats.v_free_target >
101 (vmstats.v_free_count + vmstats.v_cache_count) ||
102 vmstats.v_free_reserved > vmstats.v_free_count);
106 * Return the number of pages the pageout daemon needs to move into the
107 * cache or free lists. A negative number means we have sufficient free
110 * The target free+cache is greater than vm_page_count_target(). The
111 * frontend uses vm_page_count_target() while the backend continue freeing
112 * based on vm_paging_target().
114 * This function DOES NOT return TRUE or FALSE.
118 vm_paging_target(void)
121 (vmstats.v_free_target + vmstats.v_cache_min) -
122 (vmstats.v_free_count + vmstats.v_cache_count)
127 * Return TRUE if hysteresis dictates we should nominally wakeup the
128 * pageout daemon to start working on freeing up some memory. This
129 * routine should NOT be used to determine when to block on the VM system.
130 * We want to wakeup the pageout daemon before we might otherwise block.
132 * Paging begins when cache+free drops below cache_min + free_min.
136 vm_paging_needed(void)
138 if (vmstats.v_free_min + vmstats.v_cache_min >
139 vmstats.v_free_count + vmstats.v_cache_count) {
142 if (vmstats.v_free_min > vmstats.v_free_count)
149 vm_page_event(vm_page_t m, vm_page_event_t event)
151 if (m->flags & PG_ACTIONLIST)
152 vm_page_event_internal(m, event);
157 vm_page_init_action(vm_page_t m, vm_page_action_t action,
158 void (*func)(vm_page_t, vm_page_action_t), void *data)
166 * Clear dirty bits in the VM page but truncate the
167 * end to a DEV_BSIZE'd boundary.
169 * Used when reading data in, typically via getpages.
170 * The partial device block at the end of the truncation
171 * range should not lose its dirty bit.
173 * NOTE: This function does not clear the pmap modified bit.
177 vm_page_clear_dirty_end_nonincl(vm_page_t m, int base, int size)
179 size = (base + size) & ~DEV_BMASK;
181 vm_page_clear_dirty(m, base, size - base);
185 * Clear dirty bits in the VM page but truncate the
186 * beginning to a DEV_BSIZE'd boundary.
188 * Used when truncating a buffer. The partial device
189 * block at the beginning of the truncation range
190 * should not lose its dirty bit.
192 * NOTE: This function does not clear the pmap modified bit.
196 vm_page_clear_dirty_beg_nonincl(vm_page_t m, int base, int size)
199 base = (base + DEV_BMASK) & ~DEV_BMASK;
201 vm_page_clear_dirty(m, base, size - base);
206 vm_page_spin_lock(vm_page_t m)
213 vm_page_spin_unlock(vm_page_t m)
219 * Wire a vm_page that is already wired. Does not require a busied
224 vm_page_wire_quick(vm_page_t m)
226 if (atomic_fetchadd_int(&m->wire_count, 1) == 0)
227 panic("vm_page_wire_quick: wire_count was 0");
231 * Unwire a vm_page quickly, does not require a busied page.
233 * This routine refuses to drop the wire_count to 0 and will return
234 * TRUE if it would have had to (instead of decrementing it to 0).
235 * The caller can then busy the page and deal with it.
239 vm_page_unwire_quick(vm_page_t m)
241 KKASSERT(m->wire_count > 0);
243 u_int wire_count = m->wire_count;
248 if (atomic_cmpset_int(&m->wire_count, wire_count, wire_count - 1))
254 #endif /* _VM_VM_PAGE2_H_ */