Add a new physical memory allocator. However, do not yet connect it

to the build.

This allocator uses a binary buddy system with a twist.  First and
foremost, this allocator is required to support the implementation of
superpages.  As a side effect, it enables a more robust implementation
of contigmalloc(9).  Moreover, this reimplementation of
contigmalloc(9) eliminates the acquisition of Giant by
contigmalloc(..., M_NOWAIT, ...).

The twist is that this allocator tries to reduce the number of TLB
misses incurred by accesses through a direct map to small, UMA-managed
objects and page table pages.  Roughly speaking, the physical pages
that are allocated for such purposes are clustered together in the
physical address space.  The performance benefits vary.  In the most
extreme case, a uniprocessor kernel running on an Opteron, I measured
an 18% reduction in system time during a buildworld.

This allocator does not implement page coloring.  The reason is that
superpages have much the same effect.  The contiguous physical memory
allocation necessary for a superpage is inherently colored.

Finally, the one caveat is that this allocator does not effectively
support prezeroed pages.  I hope this is temporary.  On i386, this is
a slight pessimization.  However, on amd64, the beneficial effects of
the direct-map optimization outweigh the ill effects.  I speculate
that this is true in general of machines with a direct map.

Approved by:	re

2 files changed, 741 insertions, 0 deletions

diff --git a/sys/vm/vm_phys.c b/sys/vm/vm_phys.c
new file mode 100644
index 0000000..80a03a6
--- /dev/null
+++ b/sys/vm/vm_phys.c
@@ -0,0 +1,689 @@
+/*-
+ * Copyright (c) 2002-2006 Rice University
+ * Copyright (c) 2007 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include "opt_ddb.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/lock.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/queue.h>
+#include <sys/sbuf.h>
+#include <sys/sysctl.h>
+#include <sys/vmmeter.h>
+
+#include <ddb/ddb.h>
+
+#include <vm/vm.h>
+#include <vm/vm_param.h>
+#include <vm/vm_kern.h>
+#include <vm/vm_object.h>
+#include <vm/vm_page.h>
+#include <vm/vm_phys.h>
+
+struct vm_freelist {
+	struct pglist pl;
+	int lcnt;
+};
+
+struct vm_phys_seg {
+	vm_paddr_t	start;
+	vm_paddr_t	end;
+	vm_page_t	first_page;
+	struct vm_freelist (*free_queues)[VM_NFREEPOOL][VM_NFREEORDER];
+};
+
+static struct vm_phys_seg vm_phys_segs[VM_PHYSSEG_MAX];
+
+static int vm_phys_nsegs;
+
+static struct vm_freelist
+    vm_phys_free_queues[VM_NFREELIST][VM_NFREEPOOL][VM_NFREEORDER];
+
+static int vm_nfreelists = VM_FREELIST_DEFAULT + 1;
+
+static int cnt_prezero;
+SYSCTL_INT(_vm_stats_misc, OID_AUTO, cnt_prezero, CTLFLAG_RD,
+    &cnt_prezero, 0, "The number of physical pages prezeroed at idle time");
+
+static int sysctl_vm_phys_free(SYSCTL_HANDLER_ARGS);
+SYSCTL_OID(_vm, OID_AUTO, phys_free, CTLTYPE_STRING | CTLFLAG_RD,
+    NULL, 0, sysctl_vm_phys_free, "A", "Phys Free Info");
+
+static int sysctl_vm_phys_segs(SYSCTL_HANDLER_ARGS);
+SYSCTL_OID(_vm, OID_AUTO, phys_segs, CTLTYPE_STRING | CTLFLAG_RD,
+    NULL, 0, sysctl_vm_phys_segs, "A", "Phys Seg Info");
+
+static void vm_phys_create_seg(vm_paddr_t start, vm_paddr_t end, int flind);
+static int vm_phys_paddr_to_segind(vm_paddr_t pa);
+static void vm_phys_set_pool(int pool, vm_page_t m, int order);
+static void vm_phys_split_pages(vm_page_t m, int oind, struct vm_freelist *fl,
+    int order);
+
+/*
+ * Outputs the state of the physical memory allocator, specifically,
+ * the amount of physical memory in each free list.
+ */
+static int
+sysctl_vm_phys_free(SYSCTL_HANDLER_ARGS)
+{
+	struct sbuf sbuf;
+	struct vm_freelist *fl;
+	char *cbuf;
+	const int cbufsize = vm_nfreelists*(VM_NFREEORDER + 1)*81;
+	int error, flind, oind, pind;
+
+	cbuf = malloc(cbufsize, M_TEMP, M_WAITOK | M_ZERO);
+	sbuf_new(&sbuf, cbuf, cbufsize, SBUF_FIXEDLEN);
+	for (flind = 0; flind < vm_nfreelists; flind++) {
+		sbuf_printf(&sbuf, "\nFREE LIST %d:\n"
+		    "\n  ORDER (SIZE)  |  NUMBER"
+		    "\n              ", flind);
+		for (pind = 0; pind < VM_NFREEPOOL; pind++)
+			sbuf_printf(&sbuf, "  |  POOL %d", pind);
+		sbuf_printf(&sbuf, "\n--            ");
+		for (pind = 0; pind < VM_NFREEPOOL; pind++)
+			sbuf_printf(&sbuf, "-- --      ");
+		sbuf_printf(&sbuf, "--\n");
+		for (oind = VM_NFREEORDER - 1; oind >= 0; oind--) {
+			sbuf_printf(&sbuf, "  %2.2d (%6.6dK)", oind,
+			    1 << (PAGE_SHIFT - 10 + oind));
+			for (pind = 0; pind < VM_NFREEPOOL; pind++) {
+				fl = vm_phys_free_queues[flind][pind];
+				sbuf_printf(&sbuf, "  |  %6.6d", fl[oind].lcnt);
+			}
+			sbuf_printf(&sbuf, "\n");
+		}
+	}
+	sbuf_finish(&sbuf);
+	error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
+	sbuf_delete(&sbuf);
+	free(cbuf, M_TEMP);
+	return (error);
+}
+
+/*
+ * Outputs the set of physical memory segments.
+ */
+static int
+sysctl_vm_phys_segs(SYSCTL_HANDLER_ARGS)
+{
+	struct sbuf sbuf;
+	struct vm_phys_seg *seg;
+	char *cbuf;
+	const int cbufsize = VM_PHYSSEG_MAX*(VM_NFREEORDER + 1)*81;
+	int error, segind;
+
+	cbuf = malloc(cbufsize, M_TEMP, M_WAITOK | M_ZERO);
+	sbuf_new(&sbuf, cbuf, cbufsize, SBUF_FIXEDLEN);
+	for (segind = 0; segind < vm_phys_nsegs; segind++) {
+		sbuf_printf(&sbuf, "\nSEGMENT %d:\n\n", segind);
+		seg = &vm_phys_segs[segind];
+		sbuf_printf(&sbuf, "start:     %#jx\n",
+		    (uintmax_t)seg->start);
+		sbuf_printf(&sbuf, "end:       %#jx\n",
+		    (uintmax_t)seg->end);
+		sbuf_printf(&sbuf, "free list: %p\n", seg->free_queues);
+	}
+	sbuf_finish(&sbuf);
+	error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
+	sbuf_delete(&sbuf);
+	free(cbuf, M_TEMP);
+	return (error);
+}
+
+/*
+ * Create a physical memory segment.
+ */
+static void
+vm_phys_create_seg(vm_paddr_t start, vm_paddr_t end, int flind)
+{
+	struct vm_phys_seg *seg;
+#ifdef VM_PHYSSEG_SPARSE
+	long pages;
+	int segind;
+
+	pages = 0;
+	for (segind = 0; segind < vm_phys_nsegs; segind++) {
+		seg = &vm_phys_segs[segind];
+		pages += atop(seg->end - seg->start);
+	}
+#endif
+	KASSERT(vm_phys_nsegs < VM_PHYSSEG_MAX,
+	    ("vm_phys_create_seg: increase VM_PHYSSEG_MAX"));
+	seg = &vm_phys_segs[vm_phys_nsegs++];
+	seg->start = start;
+	seg->end = end;
+#ifdef VM_PHYSSEG_SPARSE
+	seg->first_page = &vm_page_array[pages];
+#else
+	seg->first_page = PHYS_TO_VM_PAGE(start);
+#endif
+	seg->free_queues = &vm_phys_free_queues[flind];
+}
+
+/*
+ * Initialize the physical memory allocator.
+ */
+void
+vm_phys_init(void)
+{
+	struct vm_freelist *fl;
+	int flind, i, oind, pind;
+
+	for (i = 0; phys_avail[i + 1] != 0; i += 2) {
+#ifdef	VM_FREELIST_ISADMA
+		if (phys_avail[i] < 16777216) {
+			if (phys_avail[i + 1] > 16777216) {
+				vm_phys_create_seg(phys_avail[i], 16777216,
+				    VM_FREELIST_ISADMA);
+				vm_phys_create_seg(16777216, phys_avail[i + 1],
+				    VM_FREELIST_DEFAULT);
+			} else {
+				vm_phys_create_seg(phys_avail[i],
+				    phys_avail[i + 1], VM_FREELIST_ISADMA);
+			}
+			if (VM_FREELIST_ISADMA >= vm_nfreelists)
+				vm_nfreelists = VM_FREELIST_ISADMA + 1;
+		} else
+#endif
+#ifdef	VM_FREELIST_HIGHMEM
+		if (phys_avail[i + 1] > VM_HIGHMEM_ADDRESS) {
+			if (phys_avail[i] < VM_HIGHMEM_ADDRESS) {
+				vm_phys_create_seg(phys_avail[i],
+				    VM_HIGHMEM_ADDRESS, VM_FREELIST_DEFAULT);
+				vm_phys_create_seg(VM_HIGHMEM_ADDRESS,
+				    phys_avail[i + 1], VM_FREELIST_HIGHMEM);
+			} else {
+				vm_phys_create_seg(phys_avail[i],
+				    phys_avail[i + 1], VM_FREELIST_HIGHMEM);
+			}
+			if (VM_FREELIST_HIGHMEM >= vm_nfreelists)
+				vm_nfreelists = VM_FREELIST_HIGHMEM + 1;
+		} else
+#endif
+		vm_phys_create_seg(phys_avail[i], phys_avail[i + 1],
+		    VM_FREELIST_DEFAULT);
+	}
+	for (flind = 0; flind < vm_nfreelists; flind++) {
+		for (pind = 0; pind < VM_NFREEPOOL; pind++) {
+			fl = vm_phys_free_queues[flind][pind];
+			for (oind = 0; oind < VM_NFREEORDER; oind++)
+				TAILQ_INIT(&fl[oind].pl);
+		}
+	}
+}
+
+/*
+ * Split a contiguous, power of two-sized set of physical pages.
+ */
+static __inline void
+vm_phys_split_pages(vm_page_t m, int oind, struct vm_freelist *fl, int order)
+{
+	vm_page_t m_buddy;
+
+	while (oind > order) {
+		oind--;
+		m_buddy = &m[1 << oind];
+		KASSERT(m_buddy->order == VM_NFREEORDER,
+		    ("vm_phys_split_pages: page %p has unexpected order %d",
+		    m_buddy, m_buddy->order));
+		m_buddy->order = oind;
+		TAILQ_INSERT_HEAD(&fl[oind].pl, m_buddy, pageq);
+		fl[oind].lcnt++;
+        }
+}
+
+/*
+ * Initialize a physical page and add it to the free lists.
+ */
+void
+vm_phys_add_page(vm_paddr_t pa)
+{
+	vm_page_t m;
+
+	cnt.v_page_count++;
+	m = vm_phys_paddr_to_vm_page(pa);
+	m->phys_addr = pa;
+	m->segind = vm_phys_paddr_to_segind(pa);
+	m->flags = PG_FREE;
+	KASSERT(m->order == VM_NFREEORDER,
+	    ("vm_phys_add_page: page %p has unexpected order %d",
+	    m, m->order));
+	m->pool = VM_FREEPOOL_DEFAULT;
+	pmap_page_init(m);
+	vm_phys_free_pages(m, 0);
+}
+
+/*
+ * Allocate a contiguous, power of two-sized set of physical pages
+ * from the free lists.
+ */
+vm_page_t
+vm_phys_alloc_pages(int pool, int order)
+{
+	vm_page_t m;
+
+	mtx_lock(&vm_page_queue_free_mtx);
+	m = vm_phys_alloc_pages_locked(pool, order);
+	mtx_unlock(&vm_page_queue_free_mtx);
+	return (m);
+}
+
+/*
+ * Allocate a contiguous, power of two-sized set of physical pages
+ * from the free lists.
+ */
+vm_page_t
+vm_phys_alloc_pages_locked(int pool, int order)
+{
+	struct vm_freelist *fl;
+	struct vm_freelist *alt;
+	int flind, oind, pind;
+	vm_page_t m;
+
+	KASSERT(pool < VM_NFREEPOOL,
+	    ("vm_phys_alloc_pages_locked: pool %d is out of range", pool));
+	KASSERT(order < VM_NFREEORDER,
+	    ("vm_phys_alloc_pages_locked: order %d is out of range", order));
+	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
+	for (flind = 0; flind < vm_nfreelists; flind++) {
+		fl = vm_phys_free_queues[flind][pool];
+		for (oind = order; oind < VM_NFREEORDER; oind++) {
+			m = TAILQ_FIRST(&fl[oind].pl);
+			if (m != NULL) {
+				TAILQ_REMOVE(&fl[oind].pl, m, pageq);
+				fl[oind].lcnt--;
+				m->order = VM_NFREEORDER;
+				vm_phys_split_pages(m, oind, fl, order);
+				cnt.v_free_count -= 1 << order;
+				return (m);
+			}
+		}
+
+		/*
+		 * The given pool was empty.  Find the largest
+		 * contiguous, power-of-two-sized set of pages in any
+		 * pool.  Transfer these pages to the given pool, and
+		 * use them to satisfy the allocation.
+		 */
+		for (oind = VM_NFREEORDER - 1; oind >= order; oind--) {
+			for (pind = 0; pind < VM_NFREEPOOL; pind++) {
+				alt = vm_phys_free_queues[flind][pind];
+				m = TAILQ_FIRST(&alt[oind].pl);
+				if (m != NULL) {
+					TAILQ_REMOVE(&alt[oind].pl, m, pageq);
+					alt[oind].lcnt--;
+					m->order = VM_NFREEORDER;
+					vm_phys_set_pool(pool, m, oind);
+					vm_phys_split_pages(m, oind, fl, order);
+					cnt.v_free_count -= 1 << order;
+					return (m);
+				}
+			}
+		}
+	}
+	return (NULL);
+}
+
+/*
+ * Allocate physical memory from phys_avail[].
+ */
+vm_paddr_t
+vm_phys_bootstrap_alloc(vm_size_t size, unsigned long alignment)
+{
+	vm_paddr_t pa;
+	int i;
+
+	size = round_page(size);
+	for (i = 0; phys_avail[i + 1] != 0; i += 2) {
+		if (phys_avail[i + 1] - phys_avail[i] < size)
+			continue;
+		pa = phys_avail[i];
+		phys_avail[i] += size;
+		return (pa);
+	}
+	panic("vm_phys_bootstrap_alloc");
+}
+
+/*
+ * Find the vm_page corresponding to the given physical address.
+ */
+vm_page_t
+vm_phys_paddr_to_vm_page(vm_paddr_t pa)
+{
+	struct vm_phys_seg *seg;
+	int segind;
+
+	for (segind = 0; segind < vm_phys_nsegs; segind++) {
+		seg = &vm_phys_segs[segind];
+		if (pa >= seg->start && pa < seg->end)
+			return (&seg->first_page[atop(pa - seg->start)]);
+	}
+	panic("vm_phys_paddr_to_vm_page: paddr %#jx is not in any segment",
+	    (uintmax_t)pa);
+}
+
+/*
+ * Find the segment containing the given physical address.
+ */
+static int
+vm_phys_paddr_to_segind(vm_paddr_t pa)
+{
+	struct vm_phys_seg *seg;
+	int segind;
+
+	for (segind = 0; segind < vm_phys_nsegs; segind++) {
+		seg = &vm_phys_segs[segind];
+		if (pa >= seg->start && pa < seg->end)
+			return (segind);
+	}
+	panic("vm_phys_paddr_to_segind: paddr %#jx is not in any segment" ,
+	    (uintmax_t)pa);
+}
+
+/*
+ * Free a contiguous, power of two-sized set of physical pages.
+ */
+void
+vm_phys_free_pages(vm_page_t m, int order)
+{
+
+	mtx_lock(&vm_page_queue_free_mtx);
+	vm_phys_free_pages_locked(m, order);
+	mtx_unlock(&vm_page_queue_free_mtx);
+}
+
+/*
+ * Free a contiguous, power of two-sized set of physical pages.
+ */
+void
+vm_phys_free_pages_locked(vm_page_t m, int order)
+{
+	struct vm_freelist *fl;
+	struct vm_phys_seg *seg;
+	vm_paddr_t pa, pa_buddy;
+	vm_page_t m_buddy;
+
+	KASSERT(m->order == VM_NFREEORDER,
+	    ("vm_phys_free_pages_locked: page %p has unexpected order %d",
+	    m, m->order));
+	KASSERT(m->pool < VM_NFREEPOOL,
+	    ("vm_phys_free_pages_locked: page %p has unexpected pool %d",
+	    m, m->pool));
+	KASSERT(order < VM_NFREEORDER,
+	    ("vm_phys_free_pages_locked: order %d is out of range", order));
+	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
+	pa = VM_PAGE_TO_PHYS(m);
+	seg = &vm_phys_segs[m->segind];
+	cnt.v_free_count += 1 << order;
+	while (order < VM_NFREEORDER - 1) {
+		pa_buddy = pa ^ (1 << (PAGE_SHIFT + order));
+		if (pa_buddy < seg->start ||
+		    pa_buddy >= seg->end)
+			break;
+		m_buddy = &seg->first_page[atop(pa_buddy - seg->start)];
+		if (m_buddy->order != order)
+			break;
+		fl = (*seg->free_queues)[m_buddy->pool];
+		TAILQ_REMOVE(&fl[m_buddy->order].pl, m_buddy, pageq);
+		fl[m_buddy->order].lcnt--;
+		m_buddy->order = VM_NFREEORDER;
+		if (m_buddy->pool != m->pool)
+			vm_phys_set_pool(m->pool, m_buddy, order);
+		order++;
+		pa &= ~((1 << (PAGE_SHIFT + order)) - 1);
+		m = &seg->first_page[atop(pa - seg->start)];
+	}
+	m->order = order;
+	fl = (*seg->free_queues)[m->pool];
+	TAILQ_INSERT_TAIL(&fl[order].pl, m, pageq);
+	fl[order].lcnt++;
+}
+
+/*
+ * Set the pool for a contiguous, power of two-sized set of physical pages. 
+ */
+static void
+vm_phys_set_pool(int pool, vm_page_t m, int order)
+{
+	vm_page_t m_tmp;
+
+	for (m_tmp = m; m_tmp < &m[1 << order]; m_tmp++)
+		m_tmp->pool = pool;
+}
+
+/*
+ * Try to zero one or more physical pages.  Used by an idle priority thread.
+ */
+boolean_t
+vm_phys_zero_pages_idle(void)
+{
+	struct vm_freelist *fl;
+	vm_page_t m, m_tmp;
+	int flind, pind, q, zeroed;
+
+	mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
+	for (flind = 0; flind < vm_nfreelists; flind++) {
+		pind = VM_FREEPOOL_DEFAULT;
+		fl = vm_phys_free_queues[flind][pind];
+		for (q = 0; q < VM_NFREEORDER; q++) {
+			m = TAILQ_FIRST(&fl[q].pl);
+			if (m != NULL && (m->flags & PG_ZERO) == 0) {
+				TAILQ_REMOVE(&fl[q].pl, m, pageq);
+				fl[q].lcnt--;
+				m->order = VM_NFREEORDER;
+				cnt.v_free_count -= 1 << q;
+				mtx_unlock(&vm_page_queue_free_mtx);
+				zeroed = 0;
+				for (m_tmp = m; m_tmp < &m[1 << q]; m_tmp++) {
+					if ((m_tmp->flags & PG_ZERO) == 0) {
+						pmap_zero_page_idle(m_tmp);
+						m_tmp->flags |= PG_ZERO;
+						zeroed++;
+					}
+				}
+				cnt_prezero += zeroed;
+				mtx_lock(&vm_page_queue_free_mtx);
+				vm_phys_free_pages_locked(m, q);
+				vm_page_zero_count += zeroed;
+				return (TRUE);
+			}
+		}
+	}
+	return (FALSE);
+}
+
+/*
+ * Allocate a contiguous set of physical pages of the given size from
+ * the free lists.  All of the physical pages must be at or above the
+ * given physical address "low" and below the given physical address
+ * "high".  If the given value "alignment" is non-zero, then the
+ * lowest page in the set must be aligned to that value.  If the given
+ * value "boundary" is non-zero, then the set of physical pages cannot
+ * cross any boundary that is a multiple of that value.  Both
+ * "alignment" and "boundary" must be a power of two.
+ */
+vm_page_t
+vm_phys_alloc_contig(unsigned long npages, vm_paddr_t low, vm_paddr_t high,
+    unsigned long alignment, unsigned long boundary)
+{
+	struct vm_freelist *fl;
+	struct vm_phys_seg *seg;
+	vm_paddr_t pa, pa_last, size;
+	vm_page_t m, m_ret;
+	int flind, i, oind, order, pind;
+
+	size = npages << PAGE_SHIFT;
+	KASSERT(size != 0,
+	    ("vm_phys_alloc_contig: size must not be 0"));
+	KASSERT((alignment & (alignment - 1)) == 0,
+	    ("vm_phys_alloc_contig: alignment must be a power of 2"));
+	KASSERT((boundary & (boundary - 1)) == 0,
+	    ("vm_phys_alloc_contig: boundary must be a power of 2"));
+	/* Compute the queue that is the best fit for npages. */
+	for (order = 0; (1 << order) < npages; order++);
+	mtx_lock(&vm_page_queue_free_mtx);
+	for (flind = 0; flind < vm_nfreelists; flind++) {
+		for (oind = min(order, VM_NFREEORDER - 1); oind < VM_NFREEORDER; oind++) {
+			for (pind = 0; pind < VM_NFREEPOOL; pind++) {
+				fl = vm_phys_free_queues[flind][pind];
+				TAILQ_FOREACH(m_ret, &fl[oind].pl, pageq) {
+					/*
+					 * A free list may contain physical pages
+					 * from one or more segments.
+					 */
+					seg = &vm_phys_segs[m_ret->segind];
+					if (seg->start > high ||
+					    low >= seg->end)
+						continue;
+
+					/*
+					 * Is the size of this allocation request
+					 * larger than the largest block size?
+					 */
+					if (order >= VM_NFREEORDER) {
+						/*
+						 * Determine if a sufficient number
+						 * of subsequent blocks to satisfy
+						 * the allocation request are free.
+						 */
+						pa = VM_PAGE_TO_PHYS(m_ret);
+						pa_last = pa + size;
+						for (;;) {
+							pa += 1 << (PAGE_SHIFT + VM_NFREEORDER - 1);
+							if (pa >= pa_last)
+								break;
+							if (pa < seg->start ||
+							    pa >= seg->end)
+								break;
+							m = &seg->first_page[atop(pa - seg->start)];
+							if (m->order != VM_NFREEORDER - 1)
+								break;
+						}
+						/* If not, continue to the next block. */
+						if (pa < pa_last)
+							continue;
+					}
+
+					/*
+					 * Determine if the blocks are within the given range,
+					 * satisfy the given alignment, and do not cross the
+					 * given boundary.
+					 */
+					pa = VM_PAGE_TO_PHYS(m_ret);
+					if (pa >= low &&
+					    pa + size <= high &&
+					    (pa & (alignment - 1)) == 0 &&
+					    ((pa ^ (pa + size - 1)) & ~(boundary - 1)) == 0)
+						goto done;
+				}
+			}
+		}
+	}
+	mtx_unlock(&vm_page_queue_free_mtx);
+	return (NULL);
+done:
+	for (m = m_ret; m < &m_ret[npages]; m = &m[1 << oind]) {
+		fl = (*seg->free_queues)[m->pool];
+		TAILQ_REMOVE(&fl[m->order].pl, m, pageq);
+		fl[m->order].lcnt--;
+		m->order = VM_NFREEORDER;
+	}
+	if (m_ret->pool != VM_FREEPOOL_DEFAULT)
+		vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m_ret, oind);
+	fl = (*seg->free_queues)[m_ret->pool];
+	vm_phys_split_pages(m_ret, oind, fl, order);
+	cnt.v_free_count -= roundup2(npages, 1 << imin(oind, order));
+	for (i = 0; i < npages; i++) {
+		m = &m_ret[i];
+		KASSERT(m->queue == PQ_NONE,
+		    ("vm_phys_alloc_contig: page %p has unexpected queue %d",
+		    m, m->queue));
+		m->valid = VM_PAGE_BITS_ALL;
+		if (m->flags & PG_ZERO)
+			vm_page_zero_count--;
+		/* Don't clear the PG_ZERO flag; we'll need it later. */
+		m->flags = PG_UNMANAGED | (m->flags & PG_ZERO);
+		m->oflags = 0;
+		KASSERT(m->dirty == 0,
+		    ("vm_phys_alloc_contig: page %p was dirty", m));
+		m->wire_count = 0;
+		m->busy = 0;
+	}
+	for (; i < roundup2(npages, 1 << imin(oind, order)); i++) {
+		m = &m_ret[i];
+		KASSERT(m->order == VM_NFREEORDER,
+		    ("vm_phys_alloc_contig: page %p has unexpected order %d",
+		    m, m->order));
+		vm_phys_free_pages_locked(m, 0);
+	}
+	mtx_unlock(&vm_page_queue_free_mtx);
+	return (m_ret);
+}
+
+#ifdef DDB
+/*
+ * Show the number of physical pages in each of the free lists.
+ */
+DB_SHOW_COMMAND(freepages, db_show_freepages)
+{
+	struct vm_freelist *fl;
+	int flind, oind, pind;
+
+	for (flind = 0; flind < vm_nfreelists; flind++) {
+		db_printf("FREE LIST %d:\n"
+		    "\n  ORDER (SIZE)  |  NUMBER"
+		    "\n              ", flind);
+		for (pind = 0; pind < VM_NFREEPOOL; pind++)
+			db_printf("  |  POOL %d", pind);
+		db_printf("\n--            ");
+		for (pind = 0; pind < VM_NFREEPOOL; pind++)
+			db_printf("-- --      ");
+		db_printf("--\n");
+		for (oind = VM_NFREEORDER - 1; oind >= 0; oind--) {
+			db_printf("  %2.2d (%6.6dK)", oind,
+			    1 << (PAGE_SHIFT - 10 + oind));
+			for (pind = 0; pind < VM_NFREEPOOL; pind++) {
+				fl = vm_phys_free_queues[flind][pind];
+				db_printf("  |  %6.6d", fl[oind].lcnt);
+			}
+			db_printf("\n");
+		}
+		db_printf("\n");
+	}
+}
+#endif
diff --git a/sys/vm/vm_phys.h b/sys/vm/vm_phys.h
new file mode 100644
index 0000000..4d34ccf
--- /dev/null
+++ b/sys/vm/vm_phys.h
@@ -0,0 +1,52 @@
+/*-
+ * Copyright (c) 2002-2006 Rice University
+ * 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.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ *	Physical memory system definitions
+ */
+
+#ifndef	_VM_PHYS_H_
+#define	_VM_PHYS_H_
+
+void vm_phys_add_page(vm_paddr_t pa);
+vm_page_t vm_phys_alloc_contig(unsigned long npages,
+    vm_paddr_t low, vm_paddr_t high,
+    unsigned long alignment, unsigned long boundary);
+vm_page_t vm_phys_alloc_pages(int pool, int order);
+vm_page_t vm_phys_alloc_pages_locked(int pool, int order);
+vm_paddr_t vm_phys_bootstrap_alloc(vm_size_t size, unsigned long alignment);
+void vm_phys_free_pages(vm_page_t m, int order);
+void vm_phys_free_pages_locked(vm_page_t m, int order);
+void vm_phys_init(void);
+boolean_t vm_phys_zero_pages_idle(void);
+
+#endif	/* !_VM_PHYS_H_ */