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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.
96 * User threads doing normal allocations might wait based on this
97 * function but MUST NOT wait in a loop based on this function as the
98 * VM load may prevent the target from being reached.
102 vm_page_count_target(void)
104 return (vmstats.v_free_target >
105 (vmstats.v_free_count + vmstats.v_cache_count) ||
106 vmstats.v_free_reserved > vmstats.v_free_count);
110 * Return the number of pages the pageout daemon needs to move into the
111 * cache or free lists. A negative number means we have sufficient free
114 * The target free+cache is greater than vm_page_count_target(). The
115 * frontend uses vm_page_count_target() while the backend continue freeing
116 * based on vm_paging_target().
118 * This function DOES NOT return TRUE or FALSE.
122 vm_paging_target(void)
125 (vmstats.v_free_target + vmstats.v_cache_min) -
126 (vmstats.v_free_count + vmstats.v_cache_count)
131 * Return TRUE if hysteresis dictates we should nominally wakeup the
132 * pageout daemon to start working on freeing up some memory. This
133 * routine should NOT be used to determine when to block on the VM system.
134 * We want to wakeup the pageout daemon before we might otherwise block.
136 * Paging begins when cache+free drops below cache_min + free_min.
140 vm_paging_needed(void)
142 if (vmstats.v_free_min + vmstats.v_cache_min >
143 vmstats.v_free_count + vmstats.v_cache_count) {
146 if (vmstats.v_free_min > vmstats.v_free_count)
153 vm_page_event(vm_page_t m, vm_page_event_t event)
155 if (m->flags & PG_ACTIONLIST)
156 vm_page_event_internal(m, event);
161 vm_page_init_action(vm_page_t m, vm_page_action_t action,
162 void (*func)(vm_page_t, vm_page_action_t), void *data)
170 * Clear dirty bits in the VM page but truncate the
171 * end to a DEV_BSIZE'd boundary.
173 * Used when reading data in, typically via getpages.
174 * The partial device block at the end of the truncation
175 * range should not lose its dirty bit.
177 * NOTE: This function does not clear the pmap modified bit.
181 vm_page_clear_dirty_end_nonincl(vm_page_t m, int base, int size)
183 size = (base + size) & ~DEV_BMASK;
185 vm_page_clear_dirty(m, base, size - base);
189 * Clear dirty bits in the VM page but truncate the
190 * beginning to a DEV_BSIZE'd boundary.
192 * Used when truncating a buffer. The partial device
193 * block at the beginning of the truncation range
194 * should not lose its dirty bit.
196 * NOTE: This function does not clear the pmap modified bit.
200 vm_page_clear_dirty_beg_nonincl(vm_page_t m, int base, int size)
203 base = (base + DEV_BMASK) & ~DEV_BMASK;
205 vm_page_clear_dirty(m, base, size - base);
210 vm_page_spin_lock(vm_page_t m)
217 vm_page_spin_unlock(vm_page_t m)
223 * Wire a vm_page that is already wired. Does not require a busied
228 vm_page_wire_quick(vm_page_t m)
230 if (atomic_fetchadd_int(&m->wire_count, 1) == 0)
231 panic("vm_page_wire_quick: wire_count was 0");
235 * Unwire a vm_page quickly, does not require a busied page.
237 * This routine refuses to drop the wire_count to 0 and will return
238 * TRUE if it would have had to (instead of decrementing it to 0).
239 * The caller can then busy the page and deal with it.
243 vm_page_unwire_quick(vm_page_t m)
245 KKASSERT(m->wire_count > 0);
247 u_int wire_count = m->wire_count;
252 if (atomic_cmpset_int(&m->wire_count, wire_count, wire_count - 1))
258 * Functions implemented as macros
262 vm_page_flag_set(vm_page_t m, unsigned int bits)
264 atomic_set_int(&(m)->flags, bits);
268 vm_page_flag_clear(vm_page_t m, unsigned int bits)
270 atomic_clear_int(&(m)->flags, bits);
274 * Wakeup anyone waiting for the page after potentially unbusying
275 * (hard or soft) or doing other work on a page that might make a
276 * waiter ready. The setting of PG_WANTED is integrated into the
277 * related flags and it can't be set once the flags are already
278 * clear, so there should be no races here.
282 vm_page_flash(vm_page_t m)
284 if (m->flags & PG_WANTED) {
285 vm_page_flag_clear(m, PG_WANTED);
291 * Reduce the protection of a page. This routine never raises the
292 * protection and therefore can be safely called if the page is already
293 * at VM_PROT_NONE (it will be a NOP effectively ).
295 * VM_PROT_NONE will remove all user mappings of a page. This is often
296 * necessary when a page changes state (for example, turns into a copy-on-write
297 * page or needs to be frozen for write I/O) in order to force a fault, or
298 * to force a page's dirty bits to be synchronized and avoid hardware
299 * (modified/accessed) bit update races with pmap changes.
301 * Since 'prot' is usually a constant, this inline usually winds up optimizing
302 * out the primary conditional.
304 * WARNING: VM_PROT_NONE can block, but will loop until all mappings have
305 * been cleared. Callers should be aware that other page related elements
306 * might have changed, however.
309 vm_page_protect(vm_page_t m, int prot)
311 KKASSERT(m->flags & PG_BUSY);
312 if (prot == VM_PROT_NONE) {
313 if (m->flags & (PG_WRITEABLE|PG_MAPPED)) {
314 pmap_page_protect(m, VM_PROT_NONE);
315 /* PG_WRITEABLE & PG_MAPPED cleared by call */
317 } else if ((prot == VM_PROT_READ) && (m->flags & PG_WRITEABLE)) {
318 pmap_page_protect(m, VM_PROT_READ);
319 /* PG_WRITEABLE cleared by call */
324 * Zero-fill the specified page. The entire contents of the page will be
327 static __inline boolean_t
328 vm_page_zero_fill(vm_page_t m)
330 pmap_zero_page(VM_PAGE_TO_PHYS(m));
335 * Copy the contents of src_m to dest_m. The pages must be stable but spl
336 * and other protections depend on context.
339 vm_page_copy(vm_page_t src_m, vm_page_t dest_m)
341 pmap_copy_page(VM_PAGE_TO_PHYS(src_m), VM_PAGE_TO_PHYS(dest_m));
342 dest_m->valid = VM_PAGE_BITS_ALL;
343 dest_m->dirty = VM_PAGE_BITS_ALL;
347 * Free a page. The page must be marked BUSY.
349 * Always clear PG_ZERO when freeing a page, which ensures the flag is not
350 * set unless we are absolutely certain the page is zerod. This is
351 * particularly important when the vm_page_alloc*() code moves pages from
352 * PQ_CACHE to PQ_FREE.
355 vm_page_free(vm_page_t m)
357 vm_page_flag_clear(m, PG_ZERO);
362 * Free a page to the zerod-pages queue. The caller must ensure that the
363 * page has been zerod.
366 vm_page_free_zero(vm_page_t m)
370 char *p = (char *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m));
373 for (i = 0; i < PAGE_SIZE; i++) {
375 panic("non-zero page in vm_page_free_zero()");
380 vm_page_flag_set(m, PG_ZERO);
385 * Set page to not be dirty. Note: does not clear pmap modify bits .
388 vm_page_undirty(vm_page_t m)
394 #endif /* _VM_VM_PAGE2_H_ */