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/*-
* Copyright (c) 2002-2006 Rice University
* Copyright (c) 2007-2008 Alan L. Cox <alc@cs.rice.edu>
* All rights reserved.
*
* This software was developed for the FreeBSD Project by Alan L. Cox,
* Olivier Crameri, Peter Druschel, Sitaram Iyer, and Juan Navarro.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
* WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Superpage reservation management module
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/vm/vm_reserv.c 234771 2012-04-28 20:34:14Z alc $");
#include "opt_vm.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/queue.h>
#include <sys/sbuf.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_phys.h>
#include <vm/vm_reserv.h>
/*
* The reservation system supports the speculative allocation of large physical
* pages ("superpages"). Speculative allocation enables the fully-automatic
* utilization of superpages by the virtual memory system. In other words, no
* programmatic directives are required to use superpages.
*/
#if VM_NRESERVLEVEL > 0
/*
* The number of small pages that are contained in a level 0 reservation
*/
#define VM_LEVEL_0_NPAGES (1 << VM_LEVEL_0_ORDER)
/*
* The number of bits by which a physical address is shifted to obtain the
* reservation number
*/
#define VM_LEVEL_0_SHIFT (VM_LEVEL_0_ORDER + PAGE_SHIFT)
/*
* The size of a level 0 reservation in bytes
*/
#define VM_LEVEL_0_SIZE (1 << VM_LEVEL_0_SHIFT)
/*
* Computes the index of the small page underlying the given (object, pindex)
* within the reservation's array of small pages.
*/
#define VM_RESERV_INDEX(object, pindex) \
(((object)->pg_color + (pindex)) & (VM_LEVEL_0_NPAGES - 1))
/*
* The reservation structure
*
* A reservation structure is constructed whenever a large physical page is
* speculatively allocated to an object. The reservation provides the small
* physical pages for the range [pindex, pindex + VM_LEVEL_0_NPAGES) of offsets
* within that object. The reservation's "popcnt" tracks the number of these
* small physical pages that are in use at any given time. When and if the
* reservation is not fully utilized, it appears in the queue of partially-
* populated reservations. The reservation always appears on the containing
* object's list of reservations.
*
* A partially-populated reservation can be broken and reclaimed at any time.
*/
struct vm_reserv {
TAILQ_ENTRY(vm_reserv) partpopq;
LIST_ENTRY(vm_reserv) objq;
vm_object_t object; /* containing object */
vm_pindex_t pindex; /* offset within object */
vm_page_t pages; /* first page of a superpage */
int popcnt; /* # of pages in use */
char inpartpopq;
};
/*
* The reservation array
*
* This array is analoguous in function to vm_page_array. It differs in the
* respect that it may contain a greater number of useful reservation
* structures than there are (physical) superpages. These "invalid"
* reservation structures exist to trade-off space for time in the
* implementation of vm_reserv_from_page(). Invalid reservation structures are
* distinguishable from "valid" reservation structures by inspecting the
* reservation's "pages" field. Invalid reservation structures have a NULL
* "pages" field.
*
* vm_reserv_from_page() maps a small (physical) page to an element of this
* array by computing a physical reservation number from the page's physical
* address. The physical reservation number is used as the array index.
*
* An "active" reservation is a valid reservation structure that has a non-NULL
* "object" field and a non-zero "popcnt" field. In other words, every active
* reservation belongs to a particular object. Moreover, every active
* reservation has an entry in the containing object's list of reservations.
*/
static vm_reserv_t vm_reserv_array;
/*
* The partially-populated reservation queue
*
* This queue enables the fast recovery of an unused cached or free small page
* from a partially-populated reservation. The reservation at the head of
* this queue is the least-recently-changed, partially-populated reservation.
*
* Access to this queue is synchronized by the free page queue lock.
*/
static TAILQ_HEAD(, vm_reserv) vm_rvq_partpop =
TAILQ_HEAD_INITIALIZER(vm_rvq_partpop);
static SYSCTL_NODE(_vm, OID_AUTO, reserv, CTLFLAG_RD, 0, "Reservation Info");
static long vm_reserv_broken;
SYSCTL_LONG(_vm_reserv, OID_AUTO, broken, CTLFLAG_RD,
&vm_reserv_broken, 0, "Cumulative number of broken reservations");
static long vm_reserv_freed;
SYSCTL_LONG(_vm_reserv, OID_AUTO, freed, CTLFLAG_RD,
&vm_reserv_freed, 0, "Cumulative number of freed reservations");
static int sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS);
SYSCTL_OID(_vm_reserv, OID_AUTO, partpopq, CTLTYPE_STRING | CTLFLAG_RD, NULL, 0,
sysctl_vm_reserv_partpopq, "A", "Partially-populated reservation queues");
static long vm_reserv_reclaimed;
SYSCTL_LONG(_vm_reserv, OID_AUTO, reclaimed, CTLFLAG_RD,
&vm_reserv_reclaimed, 0, "Cumulative number of reclaimed reservations");
static void vm_reserv_depopulate(vm_reserv_t rv);
static vm_reserv_t vm_reserv_from_page(vm_page_t m);
static boolean_t vm_reserv_has_pindex(vm_reserv_t rv,
vm_pindex_t pindex);
static void vm_reserv_populate(vm_reserv_t rv);
static void vm_reserv_reclaim(vm_reserv_t rv);
/*
* Describes the current state of the partially-populated reservation queue.
*/
static int
sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS)
{
struct sbuf sbuf;
vm_reserv_t rv;
int counter, error, level, unused_pages;
error = sysctl_wire_old_buffer(req, 0);
if (error != 0)
return (error);
sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
sbuf_printf(&sbuf, "\nLEVEL SIZE NUMBER\n\n");
for (level = -1; level <= VM_NRESERVLEVEL - 2; level++) {
counter = 0;
unused_pages = 0;
mtx_lock(&vm_page_queue_free_mtx);
TAILQ_FOREACH(rv, &vm_rvq_partpop/*[level]*/, partpopq) {
counter++;
unused_pages += VM_LEVEL_0_NPAGES - rv->popcnt;
}
mtx_unlock(&vm_page_queue_free_mtx);
sbuf_printf(&sbuf, "%5d: %6dK, %6d\n", level,
unused_pages * ((int)PAGE_SIZE / 1024), counter);
}
error = sbuf_finish(&sbuf);
sbuf_delete(&sbuf);
return (error);
}
/*
* Reduces the given reservation's population count. If the population count
* becomes zero, the reservation is destroyed. Additionally, moves the
* reservation to the tail of the partially-populated reservations queue if the
* population count is non-zero.
*
* The free page queue lock must be held.
*/
static void
vm_reserv_depopulate(vm_reserv_t rv)
{
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
KASSERT(rv->object != NULL,
("vm_reserv_depopulate: reserv %p is free", rv));
KASSERT(rv->popcnt > 0,
("vm_reserv_depopulate: reserv %p's popcnt is corrupted", rv));
if (rv->inpartpopq) {
TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
rv->inpartpopq = FALSE;
}
rv->popcnt--;
if (rv->popcnt == 0) {
LIST_REMOVE(rv, objq);
rv->object = NULL;
vm_phys_free_pages(rv->pages, VM_LEVEL_0_ORDER);
vm_reserv_freed++;
} else {
rv->inpartpopq = TRUE;
TAILQ_INSERT_TAIL(&vm_rvq_partpop, rv, partpopq);
}
}
/*
* Returns the reservation to which the given page might belong.
*/
static __inline vm_reserv_t
vm_reserv_from_page(vm_page_t m)
{
return (&vm_reserv_array[VM_PAGE_TO_PHYS(m) >> VM_LEVEL_0_SHIFT]);
}
/*
* Returns TRUE if the given reservation contains the given page index and
* FALSE otherwise.
*/
static __inline boolean_t
vm_reserv_has_pindex(vm_reserv_t rv, vm_pindex_t pindex)
{
return (((pindex - rv->pindex) & ~(VM_LEVEL_0_NPAGES - 1)) == 0);
}
/*
* Increases the given reservation's population count. Moves the reservation
* to the tail of the partially-populated reservation queue.
*
* The free page queue must be locked.
*/
static void
vm_reserv_populate(vm_reserv_t rv)
{
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
KASSERT(rv->object != NULL,
("vm_reserv_populate: reserv %p is free", rv));
KASSERT(rv->popcnt < VM_LEVEL_0_NPAGES,
("vm_reserv_populate: reserv %p is already full", rv));
if (rv->inpartpopq) {
TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
rv->inpartpopq = FALSE;
}
rv->popcnt++;
if (rv->popcnt < VM_LEVEL_0_NPAGES) {
rv->inpartpopq = TRUE;
TAILQ_INSERT_TAIL(&vm_rvq_partpop, rv, partpopq);
}
}
/*
* Allocates a page from an existing or newly-created reservation.
*
* The object and free page queue must be locked.
*/
vm_page_t
vm_reserv_alloc_page(vm_object_t object, vm_pindex_t pindex)
{
vm_page_t m, mpred, msucc;
vm_pindex_t first, leftcap, rightcap;
vm_reserv_t rv;
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
/*
* Is a reservation fundamentally not possible?
*/
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
if (pindex < VM_RESERV_INDEX(object, pindex) ||
pindex >= object->size)
return (NULL);
/*
* Look for an existing reservation.
*/
msucc = NULL;
mpred = object->root;
while (mpred != NULL) {
KASSERT(mpred->pindex != pindex,
("vm_reserv_alloc_page: pindex already allocated"));
rv = vm_reserv_from_page(mpred);
if (rv->object == object && vm_reserv_has_pindex(rv, pindex)) {
m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
/* Handle vm_page_rename(m, new_object, ...). */
if ((m->flags & (PG_CACHED | PG_FREE)) == 0)
return (NULL);
vm_reserv_populate(rv);
return (m);
} else if (mpred->pindex < pindex) {
if (msucc != NULL ||
(msucc = TAILQ_NEXT(mpred, listq)) == NULL)
break;
KASSERT(msucc->pindex != pindex,
("vm_reserv_alloc_page: pindex already allocated"));
rv = vm_reserv_from_page(msucc);
if (rv->object == object &&
vm_reserv_has_pindex(rv, pindex)) {
m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
/* Handle vm_page_rename(m, new_object, ...). */
if ((m->flags & (PG_CACHED | PG_FREE)) == 0)
return (NULL);
vm_reserv_populate(rv);
return (m);
} else if (pindex < msucc->pindex)
break;
} else if (msucc == NULL) {
msucc = mpred;
mpred = TAILQ_PREV(msucc, pglist, listq);
continue;
}
msucc = NULL;
mpred = object->root = vm_page_splay(pindex, object->root);
}
/*
* Determine the first index to the left that can be used.
*/
if (mpred == NULL)
leftcap = 0;
else if ((rv = vm_reserv_from_page(mpred))->object != object)
leftcap = mpred->pindex + 1;
else
leftcap = rv->pindex + VM_LEVEL_0_NPAGES;
/*
* Determine the first index to the right that cannot be used.
*/
if (msucc == NULL)
rightcap = pindex + VM_LEVEL_0_NPAGES;
else if ((rv = vm_reserv_from_page(msucc))->object != object)
rightcap = msucc->pindex;
else
rightcap = rv->pindex;
/*
* Determine if a reservation fits between the first index to
* the left that can be used and the first index to the right
* that cannot be used.
*/
first = pindex - VM_RESERV_INDEX(object, pindex);
if (first < leftcap || first + VM_LEVEL_0_NPAGES > rightcap)
return (NULL);
/*
* Would a new reservation extend past the end of the given object?
*/
if (object->size < first + VM_LEVEL_0_NPAGES) {
/*
* Don't allocate a new reservation if the object is a vnode or
* backed by another object that is a vnode.
*/
if (object->type == OBJT_VNODE ||
(object->backing_object != NULL &&
object->backing_object->type == OBJT_VNODE))
return (NULL);
/* Speculate that the object may grow. */
}
/*
* Allocate a new reservation.
*/
m = vm_phys_alloc_pages(VM_FREEPOOL_DEFAULT, VM_LEVEL_0_ORDER);
if (m != NULL) {
rv = vm_reserv_from_page(m);
KASSERT(rv->pages == m,
("vm_reserv_alloc_page: reserv %p's pages is corrupted",
rv));
KASSERT(rv->object == NULL,
("vm_reserv_alloc_page: reserv %p isn't free", rv));
LIST_INSERT_HEAD(&object->rvq, rv, objq);
rv->object = object;
rv->pindex = first;
KASSERT(rv->popcnt == 0,
("vm_reserv_alloc_page: reserv %p's popcnt is corrupted",
rv));
KASSERT(!rv->inpartpopq,
("vm_reserv_alloc_page: reserv %p's inpartpopq is TRUE",
rv));
vm_reserv_populate(rv);
m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
}
return (m);
}
/*
* Breaks all reservations belonging to the given object.
*/
void
vm_reserv_break_all(vm_object_t object)
{
vm_reserv_t rv;
int i;
mtx_lock(&vm_page_queue_free_mtx);
while ((rv = LIST_FIRST(&object->rvq)) != NULL) {
KASSERT(rv->object == object,
("vm_reserv_break_all: reserv %p is corrupted", rv));
if (rv->inpartpopq) {
TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
rv->inpartpopq = FALSE;
}
LIST_REMOVE(rv, objq);
rv->object = NULL;
for (i = 0; i < VM_LEVEL_0_NPAGES; i++) {
if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
vm_phys_free_pages(&rv->pages[i], 0);
else
rv->popcnt--;
}
KASSERT(rv->popcnt == 0,
("vm_reserv_break_all: reserv %p's popcnt is corrupted",
rv));
vm_reserv_broken++;
}
mtx_unlock(&vm_page_queue_free_mtx);
}
/*
* Frees the given page if it belongs to a reservation. Returns TRUE if the
* page is freed and FALSE otherwise.
*
* The free page queue lock must be held.
*/
boolean_t
vm_reserv_free_page(vm_page_t m)
{
vm_reserv_t rv;
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
rv = vm_reserv_from_page(m);
if (rv->object == NULL)
return (FALSE);
if ((m->flags & PG_CACHED) != 0 && m->pool != VM_FREEPOOL_CACHE)
vm_phys_set_pool(VM_FREEPOOL_CACHE, rv->pages,
VM_LEVEL_0_ORDER);
vm_reserv_depopulate(rv);
return (TRUE);
}
/*
* Initializes the reservation management system. Specifically, initializes
* the reservation array.
*
* Requires that vm_page_array and first_page are initialized!
*/
void
vm_reserv_init(void)
{
vm_paddr_t paddr;
int i;
/*
* Initialize the reservation array. Specifically, initialize the
* "pages" field for every element that has an underlying superpage.
*/
for (i = 0; phys_avail[i + 1] != 0; i += 2) {
paddr = roundup2(phys_avail[i], VM_LEVEL_0_SIZE);
while (paddr + VM_LEVEL_0_SIZE <= phys_avail[i + 1]) {
vm_reserv_array[paddr >> VM_LEVEL_0_SHIFT].pages =
PHYS_TO_VM_PAGE(paddr);
paddr += VM_LEVEL_0_SIZE;
}
}
}
/*
* Returns a reservation level if the given page belongs to a fully-populated
* reservation and -1 otherwise.
*/
int
vm_reserv_level_iffullpop(vm_page_t m)
{
vm_reserv_t rv;
rv = vm_reserv_from_page(m);
return (rv->popcnt == VM_LEVEL_0_NPAGES ? 0 : -1);
}
/*
* Prepare for the reactivation of a cached page.
*
* First, suppose that the given page "m" was allocated individually, i.e., not
* as part of a reservation, and cached. Then, suppose a reservation
* containing "m" is allocated by the same object. Although "m" and the
* reservation belong to the same object, "m"'s pindex may not match the
* reservation's.
*
* The free page queue must be locked.
*/
boolean_t
vm_reserv_reactivate_page(vm_page_t m)
{
vm_reserv_t rv;
int i, m_index;
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
rv = vm_reserv_from_page(m);
if (rv->object == NULL)
return (FALSE);
KASSERT((m->flags & PG_CACHED) != 0,
("vm_reserv_uncache_page: page %p is not cached", m));
if (m->object == rv->object &&
m->pindex - rv->pindex == VM_RESERV_INDEX(m->object, m->pindex))
vm_reserv_populate(rv);
else {
KASSERT(rv->inpartpopq,
("vm_reserv_uncache_page: reserv %p's inpartpopq is FALSE",
rv));
TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
rv->inpartpopq = FALSE;
LIST_REMOVE(rv, objq);
rv->object = NULL;
/* Don't vm_phys_free_pages(m, 0). */
m_index = m - rv->pages;
for (i = 0; i < m_index; i++) {
if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
vm_phys_free_pages(&rv->pages[i], 0);
else
rv->popcnt--;
}
for (i++; i < VM_LEVEL_0_NPAGES; i++) {
if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
vm_phys_free_pages(&rv->pages[i], 0);
else
rv->popcnt--;
}
KASSERT(rv->popcnt == 0,
("vm_reserv_uncache_page: reserv %p's popcnt is corrupted",
rv));
vm_reserv_broken++;
}
return (TRUE);
}
/*
* Breaks the given partially-populated reservation, releasing its cached and
* free pages to the physical memory allocator.
*
* The free page queue lock must be held.
*/
static void
vm_reserv_reclaim(vm_reserv_t rv)
{
int i;
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
KASSERT(rv->inpartpopq,
("vm_reserv_reclaim: reserv %p's inpartpopq is corrupted", rv));
TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
rv->inpartpopq = FALSE;
KASSERT(rv->object != NULL,
("vm_reserv_reclaim: reserv %p is free", rv));
LIST_REMOVE(rv, objq);
rv->object = NULL;
for (i = 0; i < VM_LEVEL_0_NPAGES; i++) {
if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
vm_phys_free_pages(&rv->pages[i], 0);
else
rv->popcnt--;
}
KASSERT(rv->popcnt == 0,
("vm_reserv_reclaim: reserv %p's popcnt is corrupted", rv));
vm_reserv_reclaimed++;
}
/*
* Breaks the reservation at the head of the partially-populated reservation
* queue, releasing its cached and free pages to the physical memory
* allocator. Returns TRUE if a reservation is broken and FALSE otherwise.
*
* The free page queue lock must be held.
*/
boolean_t
vm_reserv_reclaim_inactive(void)
{
vm_reserv_t rv;
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
if ((rv = TAILQ_FIRST(&vm_rvq_partpop)) != NULL) {
vm_reserv_reclaim(rv);
return (TRUE);
}
return (FALSE);
}
/*
* Searches the partially-populated reservation queue for the least recently
* active reservation with unused pages, i.e., cached or free, that satisfy the
* given request for contiguous physical memory. If a satisfactory reservation
* is found, it is broken. Returns TRUE if a reservation is broken and FALSE
* otherwise.
*
* The free page queue lock must be held.
*/
boolean_t
vm_reserv_reclaim_contig(vm_paddr_t size, vm_paddr_t low, vm_paddr_t high,
unsigned long alignment, unsigned long boundary)
{
vm_paddr_t pa, pa_length;
vm_reserv_t rv;
int i;
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
if (size > VM_LEVEL_0_SIZE - PAGE_SIZE)
return (FALSE);
TAILQ_FOREACH(rv, &vm_rvq_partpop, partpopq) {
pa = VM_PAGE_TO_PHYS(&rv->pages[VM_LEVEL_0_NPAGES - 1]);
if (pa + PAGE_SIZE - size < low) {
/* this entire reservation is too low; go to next */
continue;
}
pa_length = 0;
for (i = 0; i < VM_LEVEL_0_NPAGES; i++)
if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0) {
pa_length += PAGE_SIZE;
if (pa_length == PAGE_SIZE) {
pa = VM_PAGE_TO_PHYS(&rv->pages[i]);
if (pa + size > high) {
/* skip to next reservation */
break;
} else if (pa < low ||
(pa & (alignment - 1)) != 0 ||
((pa ^ (pa + size - 1)) &
~(boundary - 1)) != 0)
pa_length = 0;
}
if (pa_length >= size) {
vm_reserv_reclaim(rv);
return (TRUE);
}
} else
pa_length = 0;
}
return (FALSE);
}
/*
* Transfers the reservation underlying the given page to a new object.
*
* The object must be locked.
*/
void
vm_reserv_rename(vm_page_t m, vm_object_t new_object, vm_object_t old_object,
vm_pindex_t old_object_offset)
{
vm_reserv_t rv;
VM_OBJECT_LOCK_ASSERT(new_object, MA_OWNED);
rv = vm_reserv_from_page(m);
if (rv->object == old_object) {
mtx_lock(&vm_page_queue_free_mtx);
if (rv->object == old_object) {
LIST_REMOVE(rv, objq);
LIST_INSERT_HEAD(&new_object->rvq, rv, objq);
rv->object = new_object;
rv->pindex -= old_object_offset;
}
mtx_unlock(&vm_page_queue_free_mtx);
}
}
/*
* Allocates the virtual and physical memory required by the reservation
* management system's data structures, in particular, the reservation array.
*/
vm_paddr_t
vm_reserv_startup(vm_offset_t *vaddr, vm_paddr_t end, vm_paddr_t high_water)
{
vm_paddr_t new_end;
size_t size;
/*
* Calculate the size (in bytes) of the reservation array. Round up
* from "high_water" because every small page is mapped to an element
* in the reservation array based on its physical address. Thus, the
* number of elements in the reservation array can be greater than the
* number of superpages.
*/
size = howmany(high_water, VM_LEVEL_0_SIZE) * sizeof(struct vm_reserv);
/*
* Allocate and map the physical memory for the reservation array. The
* next available virtual address is returned by reference.
*/
new_end = end - round_page(size);
vm_reserv_array = (void *)(uintptr_t)pmap_map(vaddr, new_end, end,
VM_PROT_READ | VM_PROT_WRITE);
bzero(vm_reserv_array, size);
/*
* Return the next available physical address.
*/
return (new_end);
}
#endif /* VM_NRESERVLEVEL > 0 */