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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 $
37 #ifndef _VM_VM_PAGE2_H_
38 #define _VM_VM_PAGE2_H_
40 #ifndef _SYS_VMMETER_H_
41 #include <sys/vmmeter.h>
44 #include <sys/queue.h>
46 #ifndef _VM_VM_PAGE_H_
47 #include <vm/vm_page.h>
49 #ifndef _SYS_SPINLOCK_H_
50 #include <sys/spinlock.h>
52 #ifndef _SYS_SPINLOCK2_H_
53 #include <sys/spinlock2.h>
59 * Return TRUE if we are under our severe low-free-pages threshold
61 * This causes user processes to stall to avoid exhausting memory that
62 * the kernel might need.
64 * reserved < severe < minimum < target < paging_target
68 vm_page_count_severe(void)
70 return (vmstats.v_free_severe >
71 vmstats.v_free_count + vmstats.v_cache_count ||
72 vmstats.v_free_reserved > vmstats.v_free_count);
76 * Return TRUE if we are under our minimum low-free-pages threshold.
77 * This activates the pageout demon. The pageout demon tries to
78 * reach the target but may stop once it satisfies the minimum.
80 * reserved < severe < minimum < target < paging_target
84 vm_page_count_min(int donotcount)
86 return (vmstats.v_free_min + donotcount >
87 (vmstats.v_free_count + vmstats.v_cache_count) ||
88 vmstats.v_free_reserved > vmstats.v_free_count);
92 * Return TRUE if we are under our free page target. The pageout demon
93 * tries to reach the target but may stop once it gets past the min.
95 * User threads doing normal allocations might wait based on this
96 * function but MUST NOT wait in a loop based on this function as the
97 * VM load may prevent the target from being reached.
101 vm_page_count_target(void)
103 return (vmstats.v_free_target >
104 (vmstats.v_free_count + vmstats.v_cache_count) ||
105 vmstats.v_free_reserved > vmstats.v_free_count);
109 * Return the number of pages the pageout daemon needs to move into the
110 * cache or free lists. A negative number means we have sufficient free
113 * The target free+cache is greater than vm_page_count_target(). The
114 * frontend uses vm_page_count_target() while the backend continue freeing
115 * based on vm_paging_target().
117 * This function DOES NOT return TRUE or FALSE.
121 vm_paging_target(void)
124 (vmstats.v_free_target + vmstats.v_cache_min) -
125 (vmstats.v_free_count + vmstats.v_cache_count)
130 * Return TRUE if hysteresis dictates we should nominally wakeup the
131 * pageout daemon to start working on freeing up some memory. This
132 * routine should NOT be used to determine when to block on the VM system.
133 * We want to wakeup the pageout daemon before we might otherwise block.
135 * Paging begins when cache+free drops below cache_min + free_min.
139 vm_paging_needed(void)
141 if (vmstats.v_free_min + vmstats.v_cache_min >
142 vmstats.v_free_count + vmstats.v_cache_count) {
145 if (vmstats.v_free_min > vmstats.v_free_count)
152 vm_page_event(vm_page_t m, vm_page_event_t event)
154 if (m->flags & PG_ACTIONLIST)
155 vm_page_event_internal(m, event);
160 vm_page_init_action(vm_page_t m, vm_page_action_t action,
161 void (*func)(vm_page_t, vm_page_action_t), void *data)
169 * Clear dirty bits in the VM page but truncate the
170 * end to a DEV_BSIZE'd boundary.
172 * Used when reading data in, typically via getpages.
173 * The partial device block at the end of the truncation
174 * range should not lose its dirty bit.
176 * NOTE: This function does not clear the pmap modified bit.
180 vm_page_clear_dirty_end_nonincl(vm_page_t m, int base, int size)
182 size = (base + size) & ~DEV_BMASK;
184 vm_page_clear_dirty(m, base, size - base);
188 * Clear dirty bits in the VM page but truncate the
189 * beginning to a DEV_BSIZE'd boundary.
191 * Used when truncating a buffer. The partial device
192 * block at the beginning of the truncation range
193 * should not lose its dirty bit.
195 * NOTE: This function does not clear the pmap modified bit.
199 vm_page_clear_dirty_beg_nonincl(vm_page_t m, int base, int size)
202 base = (base + DEV_BMASK) & ~DEV_BMASK;
204 vm_page_clear_dirty(m, base, size - base);
209 vm_page_spin_lock(vm_page_t m)
216 vm_page_spin_unlock(vm_page_t m)
222 * Wire a vm_page that is already wired. Does not require a busied
227 vm_page_wire_quick(vm_page_t m)
229 if (atomic_fetchadd_int(&m->wire_count, 1) == 0)
230 panic("vm_page_wire_quick: wire_count was 0");
234 * Unwire a vm_page quickly, does not require a busied page.
236 * This routine refuses to drop the wire_count to 0 and will return
237 * TRUE if it would have had to (instead of decrementing it to 0).
238 * The caller can then busy the page and deal with it.
242 vm_page_unwire_quick(vm_page_t m)
244 KKASSERT(m->wire_count > 0);
246 u_int wire_count = m->wire_count;
251 if (atomic_cmpset_int(&m->wire_count, wire_count, wire_count - 1))
257 * Functions implemented as macros
261 vm_page_flag_set(vm_page_t m, unsigned int bits)
263 atomic_set_int(&(m)->flags, bits);
267 vm_page_flag_clear(vm_page_t m, unsigned int bits)
269 atomic_clear_int(&(m)->flags, bits);
273 * Wakeup anyone waiting for the page after potentially unbusying
274 * (hard or soft) or doing other work on a page that might make a
275 * waiter ready. The setting of PG_WANTED is integrated into the
276 * related flags and it can't be set once the flags are already
277 * clear, so there should be no races here.
281 vm_page_flash(vm_page_t m)
283 if (m->flags & PG_WANTED) {
284 vm_page_flag_clear(m, PG_WANTED);
290 * Reduce the protection of a page. This routine never raises the
291 * protection and therefore can be safely called if the page is already
292 * at VM_PROT_NONE (it will be a NOP effectively ).
294 * VM_PROT_NONE will remove all user mappings of a page. This is often
295 * necessary when a page changes state (for example, turns into a copy-on-write
296 * page or needs to be frozen for write I/O) in order to force a fault, or
297 * to force a page's dirty bits to be synchronized and avoid hardware
298 * (modified/accessed) bit update races with pmap changes.
300 * Since 'prot' is usually a constant, this inline usually winds up optimizing
301 * out the primary conditional.
303 * WARNING: VM_PROT_NONE can block, but will loop until all mappings have
304 * been cleared. Callers should be aware that other page related elements
305 * might have changed, however.
308 vm_page_protect(vm_page_t m, int prot)
310 KKASSERT(m->flags & PG_BUSY);
311 if (prot == VM_PROT_NONE) {
312 if (m->flags & (PG_WRITEABLE|PG_MAPPED)) {
313 pmap_page_protect(m, VM_PROT_NONE);
314 /* PG_WRITEABLE & PG_MAPPED cleared by call */
316 } else if ((prot == VM_PROT_READ) && (m->flags & PG_WRITEABLE)) {
317 pmap_page_protect(m, VM_PROT_READ);
318 /* PG_WRITEABLE cleared by call */
323 * Zero-fill the specified page. The entire contents of the page will be
326 static __inline boolean_t
327 vm_page_zero_fill(vm_page_t m)
329 pmap_zero_page(VM_PAGE_TO_PHYS(m));
334 * Copy the contents of src_m to dest_m. The pages must be stable but spl
335 * and other protections depend on context.
338 vm_page_copy(vm_page_t src_m, vm_page_t dest_m)
340 pmap_copy_page(VM_PAGE_TO_PHYS(src_m), VM_PAGE_TO_PHYS(dest_m));
341 dest_m->valid = VM_PAGE_BITS_ALL;
342 dest_m->dirty = VM_PAGE_BITS_ALL;
346 * Free a page. The page must be marked BUSY.
348 * Always clear PG_ZERO when freeing a page, which ensures the flag is not
349 * set unless we are absolutely certain the page is zerod. This is
350 * particularly important when the vm_page_alloc*() code moves pages from
351 * PQ_CACHE to PQ_FREE.
354 vm_page_free(vm_page_t m)
356 vm_page_flag_clear(m, PG_ZERO);
361 * Free a page to the zerod-pages queue. The caller must ensure that the
362 * page has been zerod.
365 vm_page_free_zero(vm_page_t m)
369 char *p = (char *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m));
372 for (i = 0; i < PAGE_SIZE; i++) {
374 panic("non-zero page in vm_page_free_zero()");
379 vm_page_flag_set(m, PG_ZERO);
384 * Set page to not be dirty. Note: does not clear pmap modify bits .
387 vm_page_undirty(vm_page_t m)
393 #endif /* _VM_VM_PAGE2_H_ */