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29 * @(#)vmmeter.h 8.2 (Berkeley) 7/10/94
30 * $FreeBSD: src/sys/sys/vmmeter.h,v 1.21.2.2 2002/10/10 19:28:21 dillon Exp $
33 #ifndef _VM_VM_PAGE2_H_
34 #define _VM_VM_PAGE2_H_
38 #ifndef _SYS_VMMETER_H_
39 #include <sys/vmmeter.h>
42 #include <sys/queue.h>
44 #ifndef _VM_VM_PAGE_H_
45 #include <vm/vm_page.h>
47 #ifndef _SYS_SPINLOCK_H_
48 #include <sys/spinlock.h>
50 #ifndef _SYS_SPINLOCK2_H_
51 #include <sys/spinlock2.h>
57 * VM fault rates are highly dependent on SMP locking conflicts and, on
58 * multi-socket systems, cache mastership changes for globals due to atomic
59 * ops (even simple atomic_add_*() calls). Cache mastership changes can
60 * limit the aggregate fault rate.
62 * For this reason we go through some hoops to access VM statistics for
63 * low-memory handling, pageout, and other triggers. Each cpu collects
64 * adjustments in gd->gd_vmstats_adj. These get rolled up into the global
65 * vmstats structure. The global vmstats structure is then pulled into
66 * gd->gd_vmstats by each cpu when it needs it. Critical path checks always
67 * use the pcpu gd->gd_vmstats structure.
70 * Return TRUE if we are under our severe low-free-pages threshold
72 * This causes user processes to stall to avoid exhausting memory that
73 * the kernel might need.
75 * reserved < severe < minimum < target < paging_target
79 vm_page_count_severe(void)
81 globaldata_t gd
= mycpu
;
83 return (gd
->gd_vmstats
.v_free_severe
>
84 gd
->gd_vmstats
.v_free_count
+ gd
->gd_vmstats
.v_cache_count
||
85 gd
->gd_vmstats
.v_free_reserved
> gd
->gd_vmstats
.v_free_count
);
89 * Return TRUE if we are under our minimum low-free-pages threshold.
90 * This activates the pageout demon. The pageout demon tries to
91 * reach the target but may stop once it satisfies the minimum.
93 * reserved < severe < minimum < target < paging_target
97 vm_page_count_min(int donotcount
)
99 globaldata_t gd
= mycpu
;
101 return (gd
->gd_vmstats
.v_free_min
+ donotcount
>
102 (gd
->gd_vmstats
.v_free_count
+ gd
->gd_vmstats
.v_cache_count
) ||
103 gd
->gd_vmstats
.v_free_reserved
> gd
->gd_vmstats
.v_free_count
);
107 * Return TRUE if we are under our free page target. The pageout demon
108 * tries to reach the target but may stop once it gets past the min.
110 * User threads doing normal allocations might wait based on this
111 * function but MUST NOT wait in a loop based on this function as the
112 * VM load may prevent the target from being reached.
116 vm_page_count_target(void)
118 globaldata_t gd
= mycpu
;
120 return (gd
->gd_vmstats
.v_free_target
>
121 (gd
->gd_vmstats
.v_free_count
+ gd
->gd_vmstats
.v_cache_count
) ||
122 gd
->gd_vmstats
.v_free_reserved
> gd
->gd_vmstats
.v_free_count
);
126 * Return the number of pages the pageout daemon needs to move into the
127 * cache or free lists. A negative number means we have sufficient free
130 * The target free+cache is greater than vm_page_count_target(). The
131 * frontend uses vm_page_count_target() while the backend continue freeing
132 * based on vm_paging_target().
134 * This function DOES NOT return TRUE or FALSE.
138 vm_paging_target(void)
140 globaldata_t gd
= mycpu
;
142 return ((gd
->gd_vmstats
.v_free_target
+ gd
->gd_vmstats
.v_cache_min
) -
143 (gd
->gd_vmstats
.v_free_count
+ gd
->gd_vmstats
.v_cache_count
));
147 * Return TRUE if hysteresis dictates we should nominally wakeup the
148 * pageout daemon to start working on freeing up some memory. This
149 * routine should NOT be used to determine when to block on the VM system.
150 * We want to wakeup the pageout daemon before we might otherwise block.
152 * Paging begins when cache+free drops below cache_min + free_min.
156 vm_paging_needed(void)
158 globaldata_t gd
= mycpu
;
160 if (gd
->gd_vmstats
.v_free_min
+ gd
->gd_vmstats
.v_cache_min
>
161 gd
->gd_vmstats
.v_free_count
+ gd
->gd_vmstats
.v_cache_count
) {
164 if (gd
->gd_vmstats
.v_free_min
> gd
->gd_vmstats
.v_free_count
)
171 vm_page_event(vm_page_t m
, vm_page_event_t event
)
173 if (m
->flags
& PG_ACTIONLIST
)
174 vm_page_event_internal(m
, event
);
179 vm_page_init_action(vm_page_t m
, vm_page_action_t action
,
180 void (*func
)(vm_page_t
, vm_page_action_t
), void *data
)
188 * Clear dirty bits in the VM page but truncate the
189 * end to a DEV_BSIZE'd boundary.
191 * Used when reading data in, typically via getpages.
192 * The partial device block at the end of the truncation
193 * range should not lose its dirty bit.
195 * NOTE: This function does not clear the pmap modified bit.
199 vm_page_clear_dirty_end_nonincl(vm_page_t m
, int base
, int size
)
201 size
= (base
+ size
) & ~DEV_BMASK
;
203 vm_page_clear_dirty(m
, base
, size
- base
);
207 * Clear dirty bits in the VM page but truncate the
208 * beginning to a DEV_BSIZE'd boundary.
210 * Used when truncating a buffer. The partial device
211 * block at the beginning of the truncation range
212 * should not lose its dirty bit.
214 * NOTE: This function does not clear the pmap modified bit.
218 vm_page_clear_dirty_beg_nonincl(vm_page_t m
, int base
, int size
)
221 base
= (base
+ DEV_BMASK
) & ~DEV_BMASK
;
223 vm_page_clear_dirty(m
, base
, size
- base
);
228 vm_page_spin_lock(vm_page_t m
)
235 vm_page_spin_unlock(vm_page_t m
)
237 spin_unlock(&m
->spin
);
241 * Wire a vm_page that is already wired. Does not require a busied
246 vm_page_wire_quick(vm_page_t m
)
248 if (atomic_fetchadd_int(&m
->wire_count
, 1) == 0)
249 panic("vm_page_wire_quick: wire_count was 0");
253 * Unwire a vm_page quickly, does not require a busied page.
255 * This routine refuses to drop the wire_count to 0 and will return
256 * TRUE if it would have had to (instead of decrementing it to 0).
257 * The caller can then busy the page and deal with it.
261 vm_page_unwire_quick(vm_page_t m
)
263 KKASSERT(m
->wire_count
> 0);
265 u_int wire_count
= m
->wire_count
;
270 if (atomic_cmpset_int(&m
->wire_count
, wire_count
, wire_count
- 1))
276 * Functions implemented as macros
280 vm_page_flag_set(vm_page_t m
, unsigned int bits
)
282 atomic_set_int(&(m
)->flags
, bits
);
286 vm_page_flag_clear(vm_page_t m
, unsigned int bits
)
288 atomic_clear_int(&(m
)->flags
, bits
);
292 * Wakeup anyone waiting for the page after potentially unbusying
293 * (hard or soft) or doing other work on a page that might make a
294 * waiter ready. The setting of PG_WANTED is integrated into the
295 * related flags and it can't be set once the flags are already
296 * clear, so there should be no races here.
300 vm_page_flash(vm_page_t m
)
302 if (m
->flags
& PG_WANTED
) {
303 vm_page_flag_clear(m
, PG_WANTED
);
309 * Reduce the protection of a page. This routine never raises the
310 * protection and therefore can be safely called if the page is already
311 * at VM_PROT_NONE (it will be a NOP effectively ).
313 * VM_PROT_NONE will remove all user mappings of a page. This is often
314 * necessary when a page changes state (for example, turns into a copy-on-write
315 * page or needs to be frozen for write I/O) in order to force a fault, or
316 * to force a page's dirty bits to be synchronized and avoid hardware
317 * (modified/accessed) bit update races with pmap changes.
319 * Since 'prot' is usually a constant, this inline usually winds up optimizing
320 * out the primary conditional.
322 * WARNING: VM_PROT_NONE can block, but will loop until all mappings have
323 * been cleared. Callers should be aware that other page related elements
324 * might have changed, however.
327 vm_page_protect(vm_page_t m
, int prot
)
329 KKASSERT(m
->flags
& PG_BUSY
);
330 if (prot
== VM_PROT_NONE
) {
331 if (m
->flags
& (PG_WRITEABLE
|PG_MAPPED
)) {
332 pmap_page_protect(m
, VM_PROT_NONE
);
333 /* PG_WRITEABLE & PG_MAPPED cleared by call */
335 } else if ((prot
== VM_PROT_READ
) && (m
->flags
& PG_WRITEABLE
)) {
336 pmap_page_protect(m
, VM_PROT_READ
);
337 /* PG_WRITEABLE cleared by call */
342 * Zero-fill the specified page. The entire contents of the page will be
345 static __inline boolean_t
346 vm_page_zero_fill(vm_page_t m
)
348 pmap_zero_page(VM_PAGE_TO_PHYS(m
));
353 * Copy the contents of src_m to dest_m. The pages must be stable but spl
354 * and other protections depend on context.
357 vm_page_copy(vm_page_t src_m
, vm_page_t dest_m
)
359 pmap_copy_page(VM_PAGE_TO_PHYS(src_m
), VM_PAGE_TO_PHYS(dest_m
));
360 dest_m
->valid
= VM_PAGE_BITS_ALL
;
361 dest_m
->dirty
= VM_PAGE_BITS_ALL
;
365 * Free a page. The page must be marked BUSY.
368 vm_page_free(vm_page_t m
)
374 * Free a page to the zerod-pages queue. The caller must ensure that the
375 * page has been zerod.
378 vm_page_free_zero(vm_page_t m
)
382 char *p
= (char *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m
));
385 for (i
= 0; i
< PAGE_SIZE
; i
++) {
387 panic("non-zero page in vm_page_free_zero()");
396 * Set page to not be dirty. Note: does not clear pmap modify bits .
399 vm_page_undirty(vm_page_t m
)
405 #endif /* _VM_VM_PAGE2_H_ */