This is the first part of the new kernel memory allocator. This replaces

malloc(9) and vm_zone with a slab like allocator.

Reviewed by:	arch@

1 files changed, 1900 insertions, 0 deletions

diff --git a/sys/vm/uma_core.c b/sys/vm/uma_core.c
new file mode 100644
index 0000000..5b4be4b
--- /dev/null
+++ b/sys/vm/uma_core.c
@@ -0,0 +1,1900 @@
+/*
+ * Copyright (c) 2002, Jeffrey Roberson <jroberson@chesapeake.net>
+ * All rights reserved.
+ *
+ * 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 unmodified, 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 AUTHOR ``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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ *
+ */
+
+/*
+ * uma_core.c  Implementation of the Universal Memory allocator
+ *
+ * This allocator is intended to replace the multitude of similar object caches
+ * in the standard FreeBSD kernel.  The intent is to be flexible as well as
+ * effecient.  A primary design goal is to return unused memory to the rest of
+ * the system.  This will make the system as a whole more flexible due to the 
+ * ability to move memory to subsystems which most need it instead of leaving
+ * pools of reserved memory unused.
+ *
+ * The basic ideas stem from similar slab/zone based allocators whose algorithms
+ * are well known.
+ *
+ */
+
+/*
+ * TODO:
+ *	- Improve memory usage for large allocations
+ *	- Improve INVARIANTS (0xdeadc0de write out)
+ *	- Investigate cache size adjustments
+ */
+
+/* I should really use ktr.. */
+/*
+#define UMA_DEBUG 1
+#define UMA_DEBUG_ALLOC 1
+#define UMA_DEBUG_ALLOC_1 1
+*/
+
+
+#include "opt_param.h"
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/types.h>
+#include <sys/queue.h>
+#include <sys/malloc.h>
+#include <sys/lock.h>
+#include <sys/sysctl.h>
+#include <machine/types.h>
+#include <sys/mutex.h>
+#include <sys/smp.h>
+
+#include <vm/vm.h>
+#include <vm/vm_object.h>
+#include <vm/vm_page.h>
+#include <vm/vm_param.h>
+#include <vm/vm_map.h>
+#include <vm/vm_kern.h>
+#include <vm/vm_extern.h>
+#include <vm/uma.h>
+#include <vm/uma_int.h>
+
+/*
+ * This is the zone from which all zones are spawned.  The idea is that even 
+ * the zone heads are allocated from the allocator, so we use the bss section
+ * to bootstrap us.
+ */
+static struct uma_zone master_zone;
+static uma_zone_t zones = &master_zone;
+
+/* This is the zone from which all of uma_slab_t's are allocated. */
+static uma_zone_t slabzone;
+
+/*
+ * The initial hash tables come out of this zone so they can be allocated
+ * prior to malloc coming up.
+ */
+static uma_zone_t hashzone;
+
+/*
+ * Zone that buckets come from.
+ */
+static uma_zone_t bucketzone;
+
+/* Linked list of all zones in the system */
+static LIST_HEAD(,uma_zone) uma_zones = LIST_HEAD_INITIALIZER(&uma_zones); 
+
+/* This mutex protects the zone list */
+static struct mtx uma_mtx;
+
+/* Linked list of boot time pages */
+static LIST_HEAD(,uma_slab) uma_boot_pages =
+    LIST_HEAD_INITIALIZER(&uma_boot_pages);
+
+/* Count of free boottime pages */
+static int uma_boot_free = 0;
+
+/* Is the VM done starting up? */
+static int booted = 0;
+
+/* This is the handle used to schedule our working set calculator */
+static struct callout uma_callout;
+
+/* This is mp_maxid + 1, for use while looping over each cpu */
+static int maxcpu;
+
+/*
+ * This structure is passed as the zone ctor arg so that I don't have to create
+ * a special allocation function just for zones.
+ */
+struct uma_zctor_args {
+	char *name;
+	int size;
+	uma_ctor ctor;
+	uma_dtor dtor;
+	uma_init uminit;
+	uma_fini fini;
+	int align;
+	u_int16_t flags;
+};
+
+/*
+ * This is the malloc hash table which is used to find the zone that a
+ * malloc allocation came from.  It is not currently resizeable.  The
+ * memory for the actual hash bucket is allocated in kmeminit.
+ */
+struct uma_hash mhash;
+struct uma_hash *mallochash = &mhash;
+
+/* Prototypes.. */
+
+static void *obj_alloc(uma_zone_t, int, u_int8_t *, int);
+static void *page_alloc(uma_zone_t, int, u_int8_t *, int);
+static void page_free(void *, int, u_int8_t);
+static uma_slab_t slab_zalloc(uma_zone_t, int);
+static void cache_drain(uma_zone_t);
+static void bucket_drain(uma_zone_t, uma_bucket_t);
+static void zone_drain(uma_zone_t);
+static void zone_ctor(void *, int, void *);
+static void zero_init(void *, int);
+static void zone_small_init(uma_zone_t zone);
+static void zone_large_init(uma_zone_t zone);
+static void zone_foreach(void (*zfunc)(uma_zone_t));
+static void zone_timeout(uma_zone_t zone);
+static void hash_expand(struct uma_hash *);
+static void uma_timeout(void *);
+static void uma_startup3(void);
+static void *uma_zalloc_internal(uma_zone_t, void *, int, int *, int);
+static void uma_zfree_internal(uma_zone_t,
+    void *, void *, int);
+void uma_print_zone(uma_zone_t);
+void uma_print_stats(void);
+static int sysctl_vm_zone(SYSCTL_HANDLER_ARGS);
+
+SYSCTL_OID(_vm, OID_AUTO, zone, CTLTYPE_STRING|CTLFLAG_RD,
+    NULL, 0, sysctl_vm_zone, "A", "Zone Info");
+SYSINIT(uma_startup3, SI_SUB_VM_CONF, SI_ORDER_SECOND, uma_startup3, NULL);
+
+
+/*
+ * Routine called by timeout which is used to fire off some time interval
+ * based calculations.  (working set, stats, etc.)
+ *
+ * Arguments:
+ *	arg   Unused
+ * 
+ * Returns:
+ *	Nothing
+ */
+static void
+uma_timeout(void *unused)
+{
+	zone_foreach(zone_timeout);
+
+	/* Reschedule this event */
+	callout_reset(&uma_callout, UMA_WORKING_TIME * hz, uma_timeout, NULL);
+}
+
+/*
+ * Routine to perform timeout driven calculations.  This does the working set
+ * as well as hash expanding, and per cpu statistics aggregation.
+ *
+ *  Arguments:
+ *	zone  The zone to operate on
+ *
+ *  Returns:
+ *	Nothing
+ */
+static void
+zone_timeout(uma_zone_t zone)
+{
+	uma_cache_t cache;
+	u_int64_t alloc;
+	int free;
+	int cpu;
+
+	alloc = 0;
+	free = 0;
+
+	/*
+	 * Aggregate per cpu cache statistics back to the zone.
+	 *
+	 * I may rewrite this to set a flag in the per cpu cache instead of
+	 * locking.  If the flag is not cleared on the next round I will have
+	 * to lock and do it here instead so that the statistics don't get too
+	 * far out of sync.
+	 */
+	if (!(zone->uz_flags & UMA_ZFLAG_INTERNAL)) {
+		for (cpu = 0; cpu < maxcpu; cpu++) {
+			if (CPU_ABSENT(cpu))
+				continue;
+			CPU_LOCK(zone, cpu); 
+			cache = &zone->uz_cpu[cpu];
+			/* Add them up, and reset */
+			alloc += cache->uc_allocs;
+			cache->uc_allocs = 0;
+			if (cache->uc_allocbucket)
+				free += cache->uc_allocbucket->ub_ptr + 1;
+			if (cache->uc_freebucket)
+				free += cache->uc_freebucket->ub_ptr + 1;
+			CPU_UNLOCK(zone, cpu);
+		}
+	}
+
+	/* Now push these stats back into the zone.. */
+	ZONE_LOCK(zone);
+	zone->uz_allocs += alloc;
+
+	/*
+	 * cachefree is an instantanious snapshot of what is in the per cpu
+	 * caches, not an accurate counter
+	 */
+	zone->uz_cachefree = free;
+
+	/*
+	 * Expand the zone hash table.
+	 * 
+	 * This is done if the number of slabs is larger than the hash size.
+	 * What I'm trying to do here is completely reduce collisions.  This
+	 * may be a little aggressive.  Should I allow for two collisions max?
+	 */
+
+	if ((zone->uz_flags & UMA_ZFLAG_OFFPAGE) &&
+	    !(zone->uz_flags & UMA_ZFLAG_MALLOC)) {
+		if (zone->uz_pages / zone->uz_ppera
+		    >= zone->uz_hash.uh_hashsize)
+			hash_expand(&zone->uz_hash);
+	}
+
+	/*
+	 * Here we compute the working set size as the total number of items 
+	 * left outstanding since the last time interval.  This is slightly
+	 * suboptimal. What we really want is the highest number of outstanding
+	 * items during the last time quantum.  This should be close enough.
+	 *
+	 * The working set size is used to throttle the zone_drain function.
+	 * We don't want to return memory that we may need again immediately.
+	 */
+	alloc = zone->uz_allocs - zone->uz_oallocs;
+	zone->uz_oallocs = zone->uz_allocs;
+	zone->uz_wssize = alloc;
+
+	ZONE_UNLOCK(zone);
+}
+
+/*
+ * Expands the hash table for OFFPAGE zones.  This is done from zone_timeout
+ * to reduce collisions.  This must not be done in the regular allocation path,
+ * otherwise, we can recurse on the vm while allocating pages.
+ *
+ * Arguments:
+ *	hash  The hash you want to expand by a factor of two.
+ *
+ * Returns:
+ * 	Nothing
+ *
+ * Discussion:
+ */
+static void
+hash_expand(struct uma_hash *hash)
+{
+	struct slabhead *newhash;
+	struct slabhead *oldhash;
+	uma_slab_t slab;
+	int hzonefree;
+	int hashsize;
+	int alloc;
+	int hval;
+	int i;
+
+
+	/*
+	 * Remember the old hash size and see if it has to go back to the
+ 	 * hash zone, or malloc.  The hash zone is used for the initial hash
+	 */
+
+	hashsize = hash->uh_hashsize;
+	oldhash = hash->uh_slab_hash;
+
+	if (hashsize == UMA_HASH_SIZE_INIT)
+		hzonefree = 1;
+	else
+		hzonefree = 0;
+
+
+	/* We're just going to go to a power of two greater */
+	if (hash->uh_hashsize)  {
+		alloc = sizeof(hash->uh_slab_hash[0]) * (hash->uh_hashsize * 2);
+		/* XXX Shouldn't be abusing DEVBUF here */
+		newhash = (struct slabhead *)malloc(alloc, M_DEVBUF, M_NOWAIT);
+		if (newhash == NULL) {
+			return;
+		}
+		hash->uh_hashsize *= 2;
+	} else {
+		alloc = sizeof(hash->uh_slab_hash[0]) * UMA_HASH_SIZE_INIT;
+		newhash = uma_zalloc_internal(hashzone, NULL, M_WAITOK, NULL, -1);
+		hash->uh_hashsize = UMA_HASH_SIZE_INIT;
+	}
+
+	bzero(newhash, alloc);
+
+	hash->uh_hashmask = hash->uh_hashsize - 1;
+
+	/*
+	 * I need to investigate hash algorithms for resizing without a
+	 * full rehash.
+	 */
+
+	for (i = 0; i < hashsize; i++)
+		while (!SLIST_EMPTY(&hash->uh_slab_hash[i])) {
+			slab = SLIST_FIRST(&hash->uh_slab_hash[i]);
+			SLIST_REMOVE_HEAD(&hash->uh_slab_hash[i], us_hlink);
+			hval = UMA_HASH(hash, slab->us_data);
+			SLIST_INSERT_HEAD(&newhash[hval], slab, us_hlink);
+		}
+
+	if (hash->uh_slab_hash) {
+		if (hzonefree)
+			uma_zfree_internal(hashzone,
+			    hash->uh_slab_hash, NULL, 0);
+		else
+			free(hash->uh_slab_hash, M_DEVBUF);
+	}
+	hash->uh_slab_hash = newhash;
+
+	return;
+}
+
+/*
+ * Frees all outstanding items in a bucket
+ *
+ * Arguments:
+ *	zone   The zone to free to, must be unlocked.
+ *	bucket The free/alloc bucket with items, cpu queue must be locked.
+ *
+ * Returns:
+ *	Nothing
+ */
+
+static void
+bucket_drain(uma_zone_t zone, uma_bucket_t bucket)
+{
+	uma_slab_t slab;
+	int mzone;
+	void *item;
+
+	if (bucket == NULL)
+		return;
+
+	slab = NULL;
+	mzone = 0;
+
+	/* We have to lookup the slab again for malloc.. */
+	if (zone->uz_flags & UMA_ZFLAG_MALLOC)
+		mzone = 1;
+
+	while (bucket->ub_ptr > -1)  {
+		item = bucket->ub_bucket[bucket->ub_ptr];
+#ifdef INVARIANTS
+		bucket->ub_bucket[bucket->ub_ptr] = NULL;
+		KASSERT(item != NULL,
+		    ("bucket_drain: botched ptr, item is NULL"));
+#endif
+		bucket->ub_ptr--;
+		/* 
+		 * This is extremely inefficient.  The slab pointer was passed
+		 * to uma_zfree_arg, but we lost it because the buckets don't
+		 * hold them.  This will go away when free() gets a size passed
+		 * to it.
+		 */
+		if (mzone)
+			slab = hash_sfind(mallochash,
+			    (u_int8_t *)((unsigned long)item &
+			   (~UMA_SLAB_MASK)));
+		uma_zfree_internal(zone, item, slab, 1);
+	}
+}
+
+/*
+ * Drains the per cpu caches for a zone.
+ *
+ * Arguments:
+ *	zone  The zone to drain, must be unlocked.
+ *
+ * Returns:
+ *	Nothing
+ *
+ * This function returns with the zone locked so that the per cpu queues can
+ * not be filled until zone_drain is finished.
+ *
+ */
+static void
+cache_drain(uma_zone_t zone)
+{
+	uma_bucket_t bucket;
+	uma_cache_t cache;
+	int cpu;
+
+	/*
+	 * Flush out the per cpu queues.
+	 *
+	 * XXX This causes unneccisary thrashing due to immediately having
+	 * empty per cpu queues.  I need to improve this.
+	 */
+
+	/*
+	 * We have to lock each cpu cache before locking the zone
+	 */
+	ZONE_UNLOCK(zone);
+
+	for (cpu = 0; cpu < maxcpu; cpu++) {
+		if (CPU_ABSENT(cpu))
+			continue;
+		CPU_LOCK(zone, cpu);
+		cache = &zone->uz_cpu[cpu];
+		bucket_drain(zone, cache->uc_allocbucket);
+		bucket_drain(zone, cache->uc_freebucket);
+	}
+
+	/*
+	 * Drain the bucket queues and free the buckets, we just keep two per
+	 * cpu (alloc/free).
+	 */
+	ZONE_LOCK(zone);
+	while ((bucket = LIST_FIRST(&zone->uz_full_bucket)) != NULL) {
+		LIST_REMOVE(bucket, ub_link);
+		ZONE_UNLOCK(zone);
+		bucket_drain(zone, bucket);
+		uma_zfree_internal(bucketzone, bucket, NULL, 0);
+		ZONE_LOCK(zone);
+	}
+
+	/* Now we do the free queue.. */
+	while ((bucket = LIST_FIRST(&zone->uz_free_bucket)) != NULL) {
+		LIST_REMOVE(bucket, ub_link);
+		uma_zfree_internal(bucketzone, bucket, NULL, 0);
+	}
+
+	/* We unlock here, but they will all block until the zone is unlocked */
+	for (cpu = 0; cpu < maxcpu; cpu++) {
+		if (CPU_ABSENT(cpu))
+			continue;
+		CPU_UNLOCK(zone, cpu);
+	}
+}
+
+/*
+ * Frees pages from a zone back to the system.  This is done on demand from
+ * the pageout daemon.
+ *
+ * Arguments:
+ *	zone  The zone to free pages from
+ *
+ * Returns:
+ *	Nothing.
+ */
+static void
+zone_drain(uma_zone_t zone)
+{
+	uma_slab_t slab;
+	uma_slab_t n;
+	u_int64_t extra;
+	u_int8_t flags;
+	u_int8_t *mem;
+	int i;
+
+	/*
+	 * We don't want to take pages from staticly allocated zones at this
+	 * time
+	 */
+	if (zone->uz_flags & UMA_ZFLAG_NOFREE || zone->uz_freef == NULL)
+		return;
+
+	ZONE_LOCK(zone);
+
+	if (!(zone->uz_flags & UMA_ZFLAG_INTERNAL))
+		cache_drain(zone);
+
+	if (zone->uz_free < zone->uz_wssize)
+		goto finished;
+#ifdef UMA_DEBUG
+	printf("%s working set size: %llu free items: %u\n",
+	    zone->uz_name, (unsigned long long)zone->uz_wssize, zone->uz_free);
+#endif
+	extra = zone->uz_wssize - zone->uz_free;
+	extra /= zone->uz_ipers;
+
+	/* extra is now the number of extra slabs that we can free */
+
+	if (extra == 0)
+		goto finished;
+
+	slab = LIST_FIRST(&zone->uz_free_slab);
+	while (slab && extra) {
+		n = LIST_NEXT(slab, us_link);
+
+		/* We have no where to free these to */
+		if (slab->us_flags & UMA_SLAB_BOOT) {
+			slab = n;
+			continue;
+		}
+
+		LIST_REMOVE(slab, us_link);
+		zone->uz_pages -= zone->uz_ppera;
+		zone->uz_free -= zone->uz_ipers;
+		if (zone->uz_fini)
+			for (i = 0; i < zone->uz_ipers; i++)
+				zone->uz_fini(
+				    slab->us_data + (zone->uz_rsize * i),
+				    zone->uz_size);
+		flags = slab->us_flags;
+		mem = slab->us_data;
+		if (zone->uz_flags & UMA_ZFLAG_OFFPAGE) {
+			if (zone->uz_flags & UMA_ZFLAG_MALLOC) {
+				UMA_HASH_REMOVE(mallochash,
+				    slab, slab->us_data); 
+			} else {
+				UMA_HASH_REMOVE(&zone->uz_hash,
+				    slab, slab->us_data);
+			}
+			uma_zfree_internal(slabzone, slab, NULL, 0);
+		} else if (zone->uz_flags & UMA_ZFLAG_MALLOC)
+			UMA_HASH_REMOVE(mallochash, slab, slab->us_data);
+#ifdef UMA_DEBUG
+		printf("%s: Returning %d bytes.\n",
+		    zone->uz_name, UMA_SLAB_SIZE * zone->uz_ppera);
+#endif
+		zone->uz_freef(mem, UMA_SLAB_SIZE * zone->uz_ppera, flags);
+
+		slab = n;
+		extra--;
+	}
+
+finished:
+	ZONE_UNLOCK(zone);
+}
+
+/*
+ * Allocate a new slab for a zone.  This does not insert the slab onto a list.
+ *
+ * Arguments:
+ *	zone  The zone to allocate slabs for
+ *	wait  Shall we wait?
+ *
+ * Returns:
+ *	The slab that was allocated or NULL if there is no memory and the
+ *	caller specified M_NOWAIT.
+ *	
+ */
+static uma_slab_t 
+slab_zalloc(uma_zone_t zone, int wait)
+{
+	uma_slab_t slab;	/* Starting slab */
+	u_int8_t *mem;
+	u_int8_t flags;
+	int i;
+
+#ifdef UMA_DEBUG
+	printf("slab_zalloc:  Allocating a new slab for %s\n", zone->uz_name);
+#endif
+
+	if (booted || (zone->uz_flags & UMA_ZFLAG_PRIVALLOC)) {
+		ZONE_UNLOCK(zone);
+		mtx_lock(&Giant);
+		slab = (uma_slab_t )zone->uz_allocf(zone, 
+		    zone->uz_ppera * UMA_SLAB_SIZE, &flags, wait);
+		mtx_unlock(&Giant);
+		ZONE_LOCK(zone);
+		if (slab != NULL)
+			slab->us_data = (u_int8_t *)slab;
+		else
+			return (NULL);
+	} else {
+
+		if (zone->uz_ppera > 1)
+			panic("UMA: Attemping to allocate multiple pages before vm has started.\n");
+		if (zone->uz_flags & UMA_ZFLAG_MALLOC)
+			panic("Mallocing before uma_startup2 has been called.\n");
+		if (uma_boot_free == 0)
+			panic("UMA: Ran out of pre init pages, increase UMA_BOOT_PAGES\n");
+		slab = LIST_FIRST(&uma_boot_pages);
+		LIST_REMOVE(slab, us_link);
+		uma_boot_free--;
+	}
+
+	mem = slab->us_data;
+
+	/* Alloc slab structure for offpage, otherwise adjust it's position */
+	if (!(zone->uz_flags & UMA_ZFLAG_OFFPAGE)) {
+		slab = (uma_slab_t )(mem + zone->uz_pgoff);
+	} else  {
+		slab = uma_zalloc_internal(slabzone, NULL, wait, NULL, -1);
+		if (slab == NULL)	/* XXX This should go away */
+			panic("UMA: No free slab structures");
+		if (!(zone->uz_flags & UMA_ZFLAG_MALLOC))
+			UMA_HASH_INSERT(&zone->uz_hash, slab, mem);
+	}
+	if (zone->uz_flags & UMA_ZFLAG_MALLOC) {
+#ifdef UMA_DEBUG
+		printf("Inserting %p into malloc hash from slab %p\n",
+		    mem, slab);
+#endif
+		UMA_HASH_INSERT(mallochash, slab, mem);
+	}
+
+	slab->us_zone = zone;
+	slab->us_data = mem;
+
+	/*
+	 * This is intended to spread data out across cache lines.
+	 *
+	 * This code doesn't seem to work properly on x86, and on alpha
+	 * it makes absolutely no performance difference. I'm sure it could
+	 * use some tuning, but sun makes outrageous claims about it's
+	 * performance.
+	 */
+#if 0
+	if (zone->uz_cachemax) {
+		slab->us_data += zone->uz_cacheoff;
+		zone->uz_cacheoff += UMA_CACHE_INC;
+		if (zone->uz_cacheoff > zone->uz_cachemax)
+			zone->uz_cacheoff = 0;
+	}
+#endif
+	
+	slab->us_freecount = zone->uz_ipers;
+	slab->us_firstfree = 0;
+	slab->us_flags = flags;
+	for (i = 0; i < zone->uz_ipers; i++)
+		slab->us_freelist[i] = i+1;
+
+	if (zone->uz_init)
+		for (i = 0; i < zone->uz_ipers; i++)
+			zone->uz_init(slab->us_data + (zone->uz_rsize * i),
+			    zone->uz_size);
+
+	zone->uz_pages += zone->uz_ppera;
+	zone->uz_free += zone->uz_ipers;
+
+	return (slab);
+}
+
+/*
+ * Allocates a number of pages from the system
+ *
+ * Arguments:
+ *	zone  Unused
+ *	bytes  The number of bytes requested
+ *	wait  Shall we wait?
+ *
+ * Returns:
+ *	A pointer to the alloced memory or possibly 
+ *	NULL if M_NOWAIT is set.
+ */
+static void *
+page_alloc(uma_zone_t zone, int bytes, u_int8_t *pflag, int wait)
+{
+	void *p;	/* Returned page */
+
+	/*
+	 * XXX The original zone allocator did this, but I don't think it's
+	 * neccisary in current.
+	 */
+
+	if (lockstatus(&kernel_map->lock, NULL)) {
+		*pflag = UMA_SLAB_KMEM;
+		p = (void *) kmem_malloc(kmem_map, bytes, wait);
+	} else {
+		*pflag = UMA_SLAB_KMAP;
+		p = (void *) kmem_alloc(kernel_map, bytes);
+	}
+  
+	return (p);
+}
+
+/*
+ * Allocates a number of pages from within an object
+ *
+ * Arguments:
+ *	zone   Unused
+ *	bytes  The number of bytes requested
+ *	wait   Shall we wait?
+ *
+ * Returns:
+ *	A pointer to the alloced memory or possibly 
+ *	NULL if M_NOWAIT is set.
+ */
+static void *
+obj_alloc(uma_zone_t zone, int bytes, u_int8_t *flags, int wait)
+{
+	vm_offset_t zkva;
+	vm_offset_t retkva;
+	vm_page_t p;
+	int pages;
+
+
+	if (zone->uz_pages + zone->uz_ppera > zone->uz_maxpages)
+		return (NULL);
+
+	retkva = NULL;
+	pages = zone->uz_pages;
+
+	/* 
+	 * This looks a little weird since we're getting one page at a time
+	 */
+	while (bytes > 0) {
+		p = vm_page_alloc(zone->uz_obj, pages,
+		    VM_ALLOC_INTERRUPT);
+		if (p == NULL)
+			return (NULL);
+
+		zkva = zone->uz_kva + pages * PAGE_SIZE;
+		if (retkva == NULL)
+			retkva = zkva;
+		pmap_qenter(zkva, &p, 1);
+		bytes -= PAGE_SIZE;
+		pages += 1;
+	}
+
+	*flags = UMA_SLAB_PRIV;
+
+	return ((void *)retkva);
+}
+
+/*
+ * Frees a number of pages to the system
+ * 
+ * Arguments:
+ *	mem   A pointer to the memory to be freed
+ *	size  The size of the memory being freed
+ *	flags The original p->us_flags field
+ *
+ * Returns:
+ *	Nothing
+ *
+ */
+static void
+page_free(void *mem, int size, u_int8_t flags)
+{
+	vm_map_t map;
+	if (flags & UMA_SLAB_KMEM)
+		map = kmem_map;
+	else if (flags & UMA_SLAB_KMAP)
+		map = kernel_map;
+	else
+		panic("UMA: page_free used with invalid flags %d\n", flags);
+
+	kmem_free(map, (vm_offset_t)mem, size);
+}
+
+/*
+ * Zero fill initializer
+ *
+ * Arguments/Returns follow uma_init specifications
+ *
+ */
+static void
+zero_init(void *mem, int size)
+{
+	bzero(mem, size);
+}
+
+/*
+ * Finish creating a small uma zone.  This calculates ipers, and the zone size.
+ *
+ * Arguments
+ *	zone  The zone we should initialize
+ *
+ * Returns
+ *	Nothing
+ */
+static void
+zone_small_init(uma_zone_t zone)
+{
+	int rsize;
+	int memused;
+	int ipers;
+
+	rsize = zone->uz_size;
+
+	if (rsize < UMA_SMALLEST_UNIT)
+		rsize = UMA_SMALLEST_UNIT;
+
+	if (rsize & zone->uz_align)
+		rsize = (rsize & ~zone->uz_align) + (zone->uz_align + 1);
+
+	zone->uz_rsize = rsize;
+
+	rsize += 1;	/* Account for the byte of linkage */
+	zone->uz_ipers = (UMA_SLAB_SIZE - sizeof(struct uma_slab)) / rsize;
+	zone->uz_ppera = 1;
+
+	memused = zone->uz_ipers * zone->uz_rsize;
+
+	/* Can we do any better? */
+	if ((UMA_SLAB_SIZE - memused) >= UMA_MAX_WASTE) {
+		if (zone->uz_flags & UMA_ZFLAG_INTERNAL) 
+			return;
+		ipers = UMA_SLAB_SIZE / zone->uz_rsize;
+		if (ipers > zone->uz_ipers) {
+			zone->uz_flags |= UMA_ZFLAG_OFFPAGE;
+			zone->uz_ipers = ipers;
+		}
+	}
+
+}
+
+/*
+ * Finish creating a large (> UMA_SLAB_SIZE) uma zone.  Just give in and do 
+ * OFFPAGE for now.  When I can allow for more dynamic slab sizes this will be
+ * more complicated.
+ *
+ * Arguments
+ *	zone  The zone we should initialize
+ *
+ * Returns
+ *	Nothing
+ */
+static void
+zone_large_init(uma_zone_t zone)
+{	
+	int pages;
+
+	pages = zone->uz_size / UMA_SLAB_SIZE;
+
+	/* Account for remainder */
+	if ((pages * UMA_SLAB_SIZE) < zone->uz_size)
+		pages++;
+
+	zone->uz_ppera = pages;
+	zone->uz_ipers = 1;
+
+	zone->uz_flags |= UMA_ZFLAG_OFFPAGE;
+	zone->uz_rsize = zone->uz_size;
+}
+
+/* 
+ * Zone header ctor.  This initializes all fields, locks, etc.  And inserts
+ * the zone onto the global zone list.
+ *
+ * Arguments/Returns follow uma_ctor specifications
+ *	udata  Actually uma_zcreat_args
+ *
+ */
+
+static void
+zone_ctor(void *mem, int size, void *udata)
+{
+	struct uma_zctor_args *arg = udata;
+	uma_zone_t zone = mem;
+	int cplen;
+	int cpu;
+
+	bzero(zone, size);
+	zone->uz_name = arg->name;
+	zone->uz_size = arg->size;
+	zone->uz_ctor = arg->ctor;
+	zone->uz_dtor = arg->dtor;
+	zone->uz_init = arg->uminit;
+	zone->uz_align = arg->align;
+	zone->uz_free = 0;
+	zone->uz_pages = 0;
+	zone->uz_flags = 0;
+	zone->uz_allocf = page_alloc;
+	zone->uz_freef = page_free;
+
+	if (arg->flags & UMA_ZONE_ZINIT)
+		zone->uz_init = zero_init;
+
+	if (arg->flags & UMA_ZONE_INTERNAL)
+		zone->uz_flags |= UMA_ZFLAG_INTERNAL;
+
+	if (arg->flags & UMA_ZONE_MALLOC)
+		zone->uz_flags |= UMA_ZFLAG_MALLOC;
+
+	if (arg->flags & UMA_ZONE_NOFREE)
+		zone->uz_flags |= UMA_ZFLAG_NOFREE;
+
+	if (zone->uz_size > UMA_SLAB_SIZE)
+		zone_large_init(zone);
+	else
+		zone_small_init(zone);
+
+	/* We do this so that the per cpu lock name is unique for each zone */
+	memcpy(zone->uz_lname, "PCPU ", 5);
+	cplen = min(strlen(zone->uz_name) + 1, LOCKNAME_LEN - 6);
+	memcpy(zone->uz_lname+5, zone->uz_name, cplen);
+	zone->uz_lname[LOCKNAME_LEN - 1] = '\0';
+
+	/*
+	 * If we're putting the slab header in the actual page we need to
+	 * figure out where in each page it goes.  This calculates a right 
+	 * justified offset into the memory on a ALIGN_PTR boundary.
+	 */
+	if (!(zone->uz_flags & UMA_ZFLAG_OFFPAGE)) {
+		int totsize;
+		int waste;
+
+		/* Size of the slab struct and free list */
+		totsize = sizeof(struct uma_slab) + zone->uz_ipers;
+		if (totsize & UMA_ALIGN_PTR)
+			totsize = (totsize & ~UMA_ALIGN_PTR) +
+			    (UMA_ALIGN_PTR + 1);
+		zone->uz_pgoff = UMA_SLAB_SIZE - totsize;
+
+		waste = zone->uz_pgoff;
+		waste -= (zone->uz_ipers * zone->uz_rsize);
+
+		/*
+		 * This calculates how much space we have for cache line size
+		 * optimizations.  It works by offseting each slab slightly.
+		 * Currently it breaks on x86, and so it is disabled.
+		 */
+
+		if (zone->uz_align < UMA_CACHE_INC && waste > UMA_CACHE_INC) {
+			zone->uz_cachemax = waste - UMA_CACHE_INC;
+			zone->uz_cacheoff = 0;
+		} 
+
+		totsize = zone->uz_pgoff + sizeof(struct uma_slab)
+		    + zone->uz_ipers;
+		/* I don't think it's possible, but I'll make sure anyway */
+		if (totsize > UMA_SLAB_SIZE) {
+			printf("zone %s ipers %d rsize %d size %d\n",
+			    zone->uz_name, zone->uz_ipers, zone->uz_rsize,
+			    zone->uz_size);
+			panic("UMA slab won't fit.\n");
+		}
+	} else {
+		/* hash_expand here to allocate the initial hash table */
+		hash_expand(&zone->uz_hash);
+		zone->uz_pgoff = 0;
+	}
+
+#ifdef UMA_DEBUG
+	printf("%s(%p) size = %d ipers = %d ppera = %d pgoff = %d\n",
+	    zone->uz_name, zone,
+	    zone->uz_size, zone->uz_ipers,
+	    zone->uz_ppera, zone->uz_pgoff);
+#endif
+	ZONE_LOCK_INIT(zone);
+
+	mtx_lock(&uma_mtx);
+	LIST_INSERT_HEAD(&uma_zones, zone, uz_link);
+	mtx_unlock(&uma_mtx);
+
+	/*
+	 * Some internal zones don't have room allocated for the per cpu
+	 * caches.  If we're internal, bail out here.
+	 */
+
+	if (zone->uz_flags & UMA_ZFLAG_INTERNAL)
+		return;
+
+	for (cpu = 0; cpu < maxcpu; cpu++) {
+		if (zone->uz_ipers < UMA_BUCKET_SIZE)
+			zone->uz_cpu[cpu].uc_count = zone->uz_ipers - 1;
+		else
+			zone->uz_cpu[cpu].uc_count = UMA_BUCKET_SIZE - 1;
+		CPU_LOCK_INIT(zone, cpu);
+	}
+}
+
+/*
+ * Traverses every zone in the system and calls a callback
+ *
+ * Arguments:
+ *	zfunc  A pointer to a function which accepts a zone
+ *		as an argument.
+ * 
+ * Returns:
+ *	Nothing
+ */
+static void 
+zone_foreach(void (*zfunc)(uma_zone_t))
+{
+	uma_zone_t zone;
+
+	mtx_lock(&uma_mtx);
+	LIST_FOREACH(zone, &uma_zones, uz_link) {
+		zfunc(zone);
+	}
+	mtx_unlock(&uma_mtx);
+}
+
+/* Public functions */
+/* See uma.h */
+void
+uma_startup(void *bootmem)
+{
+	struct uma_zctor_args args;
+	uma_slab_t slab;
+	int slabsize;
+	int i;
+
+#ifdef UMA_DEBUG
+	printf("Creating uma zone headers zone.\n");
+#endif
+#ifdef SMP
+	maxcpu = mp_maxid + 1;
+#else
+	maxcpu = 1;
+#endif
+#ifdef UMA_DEBUG 
+	printf("Max cpu = %d, mp_maxid = %d\n", maxcpu, mp_maxid);
+	Debugger("stop");
+#endif
+	mtx_init(&uma_mtx, "UMA lock", MTX_DEF);
+	/* "manually" Create the initial zone */
+	args.name = "UMA Zones";
+	args.size = sizeof(struct uma_zone) +
+	    (sizeof(struct uma_cache) * (maxcpu - 1));
+	args.ctor = zone_ctor;
+	args.dtor = NULL;
+	args.uminit = zero_init;
+	args.fini = NULL;
+	args.align = 32 - 1;
+	args.flags = UMA_ZONE_INTERNAL;
+	/* The initial zone has no Per cpu queues so it's smaller */
+	zone_ctor(zones, sizeof(struct uma_zone), &args);
+
+#ifdef UMA_DEBUG
+	printf("Filling boot free list.\n");
+#endif
+	for (i = 0; i < UMA_BOOT_PAGES; i++) {
+		slab = (uma_slab_t)((u_int8_t *)bootmem + (i * UMA_SLAB_SIZE));
+		slab->us_data = (u_int8_t *)slab;
+		slab->us_flags = UMA_SLAB_BOOT;
+		LIST_INSERT_HEAD(&uma_boot_pages, slab, us_link);
+		uma_boot_free++;
+	}
+
+#ifdef UMA_DEBUG
+	printf("Creating slab zone.\n");
+#endif
+
+	/*
+	 * This is the max number of free list items we'll have with
+	 * offpage slabs.
+	 */
+
+	slabsize = UMA_SLAB_SIZE - sizeof(struct uma_slab);
+	slabsize /= UMA_MAX_WASTE;
+	slabsize++;			/* In case there it's rounded */
+	slabsize += sizeof(struct uma_slab);
+
+	/* Now make a zone for slab headers */
+	slabzone = uma_zcreate("UMA Slabs",
+				slabsize,
+				NULL, NULL, NULL, NULL,
+				UMA_ALIGN_PTR, UMA_ZONE_INTERNAL);
+
+	hashzone = uma_zcreate("UMA Hash",
+	    sizeof(struct slabhead *) * UMA_HASH_SIZE_INIT,
+	    NULL, NULL, NULL, NULL,
+	    UMA_ALIGN_PTR, UMA_ZONE_INTERNAL);
+
+	bucketzone = uma_zcreate("UMA Buckets", sizeof(struct uma_bucket),
+	    NULL, NULL, NULL, NULL,
+	    UMA_ALIGN_PTR, UMA_ZONE_INTERNAL);
+
+
+#ifdef UMA_DEBUG
+	printf("UMA startup complete.\n");
+#endif
+}
+
+/* see uma.h */
+void
+uma_startup2(void *hashmem, u_long elems)
+{
+	bzero(hashmem, elems * sizeof(void *));
+	mallochash->uh_slab_hash = hashmem;
+	mallochash->uh_hashsize = elems;
+	mallochash->uh_hashmask = elems - 1;
+	booted = 1;
+#ifdef UMA_DEBUG
+	printf("UMA startup2 complete.\n");
+#endif
+}
+
+/*
+ * Initialize our callout handle
+ *
+ */
+
+static void
+uma_startup3(void)
+{
+#ifdef UMA_DEBUG
+	printf("Starting callout.\n");
+#endif
+	/* We'll be mpsafe once the vm is locked. */
+	callout_init(&uma_callout, 0);
+	callout_reset(&uma_callout, UMA_WORKING_TIME * hz, uma_timeout, NULL);
+#ifdef UMA_DEBUG
+	printf("UMA startup3 complete.\n");
+#endif
+}
+
+/* See uma.h */
+uma_zone_t  
+uma_zcreate(char *name, int size, uma_ctor ctor, uma_dtor dtor, uma_init uminit,
+		     uma_fini fini, int align, u_int16_t flags)
+		     
+{
+	struct uma_zctor_args args;
+
+	/* This stuff is essential for the zone ctor */
+	args.name = name;
+	args.size = size;
+	args.ctor = ctor;
+	args.dtor = dtor;
+	args.uminit = uminit;
+	args.fini = fini;
+	args.align = align;
+	args.flags = flags;
+
+	return (uma_zalloc_internal(zones, &args, M_WAITOK, NULL, -1));
+}
+
+/* See uma.h */
+void *
+uma_zalloc_arg(uma_zone_t zone, void *udata, int wait)
+{
+	void *item;
+	uma_cache_t cache;
+	uma_bucket_t bucket;
+	int isitem;
+	int cpu;
+
+	/* This is the fast path allocation */
+#ifdef UMA_DEBUG_ALLOC_1
+	printf("Allocating one item from %s(%p)\n", zone->uz_name, zone);
+#endif
+	cpu = PCPU_GET(cpuid);
+	CPU_LOCK(zone, cpu);
+	cache = &zone->uz_cpu[cpu];
+	cache->uc_allocs++;
+
+zalloc_start:
+	bucket = cache->uc_allocbucket;
+
+	if (bucket) {
+		if (bucket->ub_ptr > -1) {
+			item = bucket->ub_bucket[bucket->ub_ptr];
+#ifdef INVARIANTS
+			bucket->ub_bucket[bucket->ub_ptr] = NULL;
+#endif
+			bucket->ub_ptr--;
+			KASSERT(item != NULL,
+			    ("uma_zalloc: Bucket pointer mangled."));
+			cache->uc_allocs++;
+			CPU_UNLOCK(zone, cpu);
+			if (zone->uz_ctor)
+				zone->uz_ctor(item, zone->uz_size, udata);
+			return (item);
+		} else if (cache->uc_freebucket) {
+			/*
+			 * We have run out of items in our allocbucket.
+			 * See if we can switch with our free bucket.
+			 */
+			if (cache->uc_freebucket->ub_ptr > -1) {
+				uma_bucket_t swap;
+
+#ifdef UMA_DEBUG_ALLOC
+				printf("uma_zalloc: Swapping empty with alloc.\n");
+#endif
+				swap = cache->uc_freebucket;
+				cache->uc_freebucket = cache->uc_allocbucket;
+				cache->uc_allocbucket = swap;
+
+				goto zalloc_start;
+			}
+		}
+	} 
+	/*
+	 * We can get here for three reasons:
+	 *
+	 * 1) The buckets are NULL
+	 * 2) The zone is INTERNAL, and so it has no buckets.
+	 * 3) The alloc and free buckets are both empty.
+	 *
+	 * Just handoff to uma_zalloc_internal to do the hard stuff
+	 *
+	 */
+#ifdef UMA_DEBUG_ALLOC
+	printf("uma_zalloc: Falling back to zalloc_internal.\n");
+#endif
+
+	item = uma_zalloc_internal(zone, udata, wait, &isitem, cpu);
+
+#ifdef UMA_DEBUG
+	printf("uma_zalloc: zalloc_internal completed.\n");
+#endif
+
+	if (item && isitem == 0) 
+		goto zalloc_start;
+
+	/*
+	 * If isitem is set then we should just return it. The cpu lock
+	 * was unlocked when we couldn't get a bucket.
+	 */
+
+#ifdef INVARIANTS
+	if (wait == M_WAITOK)
+		KASSERT(item != NULL,
+		    ("uma_zalloc: WAITOK set but we're returning NULL"));
+#endif
+	return item;
+}
+
+/*
+ * Allocates an item for an internal zone OR fills a bucket
+ *
+ * Arguments
+ *	zone   The zone to alloc for.
+ *	udata  The data to be passed to the constructor.
+ *	wait   M_WAITOK or M_NOWAIT.
+ *	isitem The returned value is an item if this is true.
+ *	cpu    The cpu # of the cache that we should use, or -1.
+ *
+ * Returns
+ *	NULL if there is no memory and M_NOWAIT is set
+ *	An item if called on an interal zone
+ *	Non NULL if called to fill a bucket and it was successful.
+ *
+ * Discussion:
+ *	This was much cleaner before it had to do per cpu caches.  It is
+ *	complicated now because it has to handle the simple internal case, and
+ *	the more involved bucket filling and allocation.  The isitem is there
+ *	to remove a failure case.  You shouldn't fail on allocating from a zone
+ *	because there were no buckets.  This allows the exported zalloc to just
+ *	return the item.
+ *
+ */
+
+static void *
+uma_zalloc_internal(uma_zone_t zone, void *udata, int wait, int *isitem, int cpu)
+{
+	uma_bucket_t bucket;
+	uma_cache_t cache;
+	uma_slab_t slab;
+	u_int8_t freei;
+	void *item;
+
+	bucket = NULL;
+	cache = NULL;
+	item = NULL;
+
+	/*
+	 * This is to stop us from allocating per cpu buckets while we're running
+	 * out of UMA_BOOT_PAGES.  Otherwise, we would exhaust the boot pages.
+	 */
+
+	if (!booted && zone == bucketzone)
+		return (NULL);
+
+#ifdef UMA_DEBUG_ALLOC
+	printf("INTERNAL: Allocating one item from %s(%p)\n", zone->uz_name, zone);
+#endif
+	if (isitem != NULL)
+		*isitem = 0;
+
+	ZONE_LOCK(zone);
+
+        /* We got here because we need to fill some buckets */
+	if (cpu != -1) {
+		cache = &zone->uz_cpu[cpu];
+
+		zone->uz_allocs += cache->uc_allocs;
+		/* Check the free list */
+                bucket = LIST_FIRST(&zone->uz_full_bucket);
+		if (bucket) {
+			LIST_REMOVE(bucket, ub_link);
+			/* Our old one is now a free bucket */
+			if (cache->uc_allocbucket) {
+				KASSERT(cache->uc_allocbucket->ub_ptr == -1,
+				    ("uma_zalloc_internal: Freeing a non free bucket."));
+				LIST_INSERT_HEAD(&zone->uz_free_bucket,
+				    cache->uc_allocbucket, ub_link);
+			}
+			KASSERT(bucket->ub_ptr != -1,
+			    ("uma_zalloc_internal: Returning an empty bucket."));
+			/*zone->uz_free -= bucket->ub_ptr + 1;*/
+			cache->uc_allocbucket = bucket;
+			ZONE_UNLOCK(zone);
+			return (bucket);
+		} 
+		/* Bump up our uc_count so we get here less */
+		if (cache->uc_count < UMA_BUCKET_SIZE - 1)
+			cache->uc_count++;
+		/* Nothing on the free list, try to re-use the old one */
+		bucket = cache->uc_allocbucket;
+		if (bucket == NULL) {
+			/* Nope, we need a new one */
+			CPU_UNLOCK(zone, cpu);
+			ZONE_UNLOCK(zone);
+			bucket = uma_zalloc_internal(bucketzone,
+			    NULL, wait, NULL, -1);
+			CPU_LOCK(zone, cpu);
+			ZONE_LOCK(zone);
+			/* Did we lose the race? */
+			if (cache->uc_allocbucket) {
+#ifdef UMA_DEBUG
+				printf("uma_zalloc_internal: Lost race with another CPU.\n");
+#endif
+				if (bucket)
+					uma_zfree_internal(bucketzone,
+					    bucket, NULL, 0);
+				ZONE_UNLOCK(zone);
+				return (cache->uc_allocbucket);
+			}
+			cache->uc_allocbucket = bucket;
+ 
+			if (bucket) {
+#ifdef INVARIANTS
+				bzero(bucket, bucketzone->uz_size);
+#endif
+				bucket->ub_ptr = -1;
+			} else {
+				/*
+				 * We may not get a bucket if we recurse, so 
+				 * return an actual item. The rest of this code
+				 * does the right thing if the cache is NULL.
+				 */
+#ifdef UMA_DEBUG
+				printf("uma_zalloc_internal: Bucketzone returned NULL\n");
+#endif
+				CPU_UNLOCK(zone, cpu);
+				cache = NULL;
+				cpu = -1;
+			}
+		}
+	}
+
+new_slab:
+
+	/* Find a slab with some space */
+	if (zone->uz_free) {
+		if (!LIST_EMPTY(&zone->uz_part_slab)) {
+			slab = LIST_FIRST(&zone->uz_part_slab);
+		} else {
+			slab = LIST_FIRST(&zone->uz_free_slab);
+			LIST_REMOVE(slab, us_link);
+			LIST_INSERT_HEAD(&zone->uz_part_slab, slab, us_link);
+		}
+	} else {
+		/* 
+		 * This is to prevent us from recursively trying to allocate
+		 * buckets.  The problem is that if an allocation forces us to
+		 * grab a new bucket we will call page_alloc, which will go off
+		 * and cause the vm to allocate vm_map_entries.  If we need new
+		 * buckets there too we will recurse in kmem_alloc and bad 
+		 * things happen.  So instead we return a NULL bucket, and make
+		 * the code that allocates buckets smart enough to deal with it			 */ 
+		if (zone == bucketzone && zone->uz_recurse != 0) {
+			ZONE_UNLOCK(zone);
+			return (NULL);
+		}
+		zone->uz_recurse++;
+		slab = slab_zalloc(zone, wait);
+		zone->uz_recurse--;
+		if (slab)  {
+			LIST_INSERT_HEAD(&zone->uz_part_slab, slab, us_link);
+		/* 
+		 * We might not have been able to get a page, but another cpu
+		 * could have while we were unlocked.
+		 */
+		} else if (zone->uz_free == 0) {
+			ZONE_UNLOCK(zone);
+			/* If we're filling a bucket return what we have */
+			if (bucket != NULL && bucket->ub_ptr != -1) {
+				return (bucket);
+			} else
+				return (NULL);
+		} else {
+			/* Another cpu must have succeeded */
+			if ((slab = LIST_FIRST(&zone->uz_part_slab)) == NULL) {
+				slab = LIST_FIRST(&zone->uz_free_slab);
+				LIST_REMOVE(slab, us_link);
+				LIST_INSERT_HEAD(&zone->uz_part_slab,
+				    slab, us_link);
+			}
+		}
+	}
+
+	while (slab->us_freecount) {
+		freei = slab->us_firstfree;
+		slab->us_firstfree = slab->us_freelist[freei];
+#ifdef INVARIANTS
+		slab->us_freelist[freei] = 255;
+#endif
+		slab->us_freecount--;
+		zone->uz_free--;
+		item = slab->us_data + (zone->uz_rsize * freei);
+
+		if (cache == NULL) {
+			zone->uz_allocs++;
+			break;
+		}
+
+		bucket->ub_bucket[++bucket->ub_ptr] = item;
+
+		/* Don't overfill the bucket! */
+		if (bucket->ub_ptr == cache->uc_count) 
+			break;
+	}
+
+	/* Move this slab to the full list */
+	if (slab->us_freecount == 0) {
+		LIST_REMOVE(slab, us_link);
+		LIST_INSERT_HEAD(&zone->uz_full_slab, slab, us_link);
+	}
+
+	if (cache != NULL) {
+		/* Try to keep the buckets totally full, but don't block */
+		if (bucket->ub_ptr < cache->uc_count) {
+			wait = M_NOWAIT;
+			goto new_slab;
+		}
+	}
+
+	ZONE_UNLOCK(zone);
+
+	/* Only construct at this time if we're not filling a bucket */
+	if (cache == NULL)  {
+		if (zone->uz_ctor)
+			zone->uz_ctor(item, zone->uz_size, udata);
+
+		if (isitem != NULL)
+			*isitem = 1;
+	} 
+
+	return (item);
+}
+
+/* See uma.h */
+void
+uma_zfree_arg(uma_zone_t zone, void *item, void *udata)
+{
+	uma_cache_t cache;
+	uma_bucket_t bucket;
+	int cpu;
+
+	/* This is the fast path free */
+#ifdef UMA_DEBUG_ALLOC_1
+	printf("Freeing item %p to %s(%p)\n", item, zone->uz_name, zone);
+#endif
+	cpu = PCPU_GET(cpuid);
+	CPU_LOCK(zone, cpu);
+	cache = &zone->uz_cpu[cpu];
+
+zfree_start:
+	bucket = cache->uc_freebucket;
+
+	if (bucket) {
+		/* Do we have room in our bucket? */
+		if (bucket->ub_ptr < cache->uc_count) {
+			bucket->ub_ptr++;
+			KASSERT(bucket->ub_bucket[bucket->ub_ptr] == NULL,
+			    ("uma_zfree: Freeing to non free bucket index."));
+			bucket->ub_bucket[bucket->ub_ptr] = item;
+			CPU_UNLOCK(zone, cpu);
+			if (zone->uz_dtor)
+				zone->uz_dtor(item, zone->uz_size, udata);
+			return;
+		} else if (cache->uc_allocbucket) {
+#ifdef UMA_DEBUG_ALLOC
+			printf("uma_zfree: Swapping buckets.\n");
+#endif
+			/*
+			 * We have run out of space in our freebucket.
+			 * See if we can switch with our alloc bucket.
+			 */
+			if (cache->uc_allocbucket->ub_ptr < 
+			    cache->uc_freebucket->ub_ptr) {
+				uma_bucket_t swap;
+
+				swap = cache->uc_freebucket;
+				cache->uc_freebucket = cache->uc_allocbucket;
+				cache->uc_allocbucket = swap;
+
+				goto zfree_start;
+			}
+		}
+	} 
+
+	/*
+	 * We can get here for three reasons:
+	 *
+	 * 1) The buckets are NULL
+	 * 2) The zone is INTERNAL, and so it has no buckets.
+	 * 3) The alloc and free buckets are both somewhat full.
+	 *
+	 */
+
+	ZONE_LOCK(zone);
+
+	if (!(zone->uz_flags & UMA_ZFLAG_INTERNAL)) {
+		bucket = cache->uc_freebucket;
+		cache->uc_freebucket = NULL;
+
+		/* Can we throw this on the zone full list? */
+		if (bucket != NULL) {
+#ifdef UMA_DEBUG_ALLOC
+			printf("uma_zfree: Putting old bucket on the free list.\n");
+#endif
+			/* ub_ptr is pointing to the last free item */
+			KASSERT(bucket->ub_ptr != -1,
+			    ("uma_zfree: Attempting to insert an empty bucket onto the full list.\n"));
+			/*zone->uz_free += bucket->ub_ptr + 1;*/
+			LIST_INSERT_HEAD(&zone->uz_full_bucket,
+			    bucket, ub_link);
+			bucket = LIST_FIRST(&zone->uz_free_bucket);
+			if (bucket)
+				LIST_REMOVE(bucket, ub_link);
+		}
+		/*
+		 * Do we need to alloc one? Either the freebucket was NULL
+		 * or the free_bucket list was empty.
+		 */
+		if (bucket == NULL) {
+#ifdef UMA_DEBUG_ALLOC
+			printf("uma_zfree: Allocating new free bucket.\n");
+#endif
+			/* This has to be done so we don't recurse on a lock */
+			ZONE_UNLOCK(zone);
+			CPU_UNLOCK(zone, cpu);
+			bucket = uma_zalloc_internal(bucketzone,
+			    NULL, M_NOWAIT, NULL, -1);
+			CPU_LOCK(zone, cpu);
+			ZONE_LOCK(zone);
+			if (bucket) {
+#ifdef INVARIANTS
+				bzero(bucket, bucketzone->uz_size);
+#endif
+				bucket->ub_ptr = -1;
+			}
+			/* Did we lose the race? */
+			if (cache->uc_freebucket != NULL) {
+				if (bucket)
+					uma_zfree_internal(bucketzone,
+					    bucket, NULL, 0);
+				ZONE_UNLOCK(zone);
+				goto zfree_start;
+			}
+			/* If we couldn't get one just free directly */
+			if (bucket == NULL) 
+				goto zfree_internal;
+		}
+		cache->uc_freebucket = bucket;
+		ZONE_UNLOCK(zone);
+		goto zfree_start;
+	} 
+
+zfree_internal:
+
+	CPU_UNLOCK(zone, cpu);
+	ZONE_UNLOCK(zone);
+	uma_zfree_internal(zone, item, udata, 0);
+
+	return;
+
+}
+
+/*
+ * Frees an item to an INTERNAL zone or allocates a free bucket
+ *
+ * Arguments:
+ *	zone   The zone to free to
+ *	item   The item we're freeing
+ *	udata  User supplied data for the dtor
+ *	skip   Skip the dtor, it was done in uma_zfree_arg
+ */
+
+static void
+uma_zfree_internal(uma_zone_t zone, void *item, void *udata, int skip)
+{
+	uma_slab_t slab;
+	u_int8_t *mem;
+	u_int8_t freei;
+
+	ZONE_LOCK(zone);
+
+	if (!(zone->uz_flags & UMA_ZFLAG_MALLOC)) {
+		mem = (u_int8_t *)((unsigned long)item & (~UMA_SLAB_MASK));
+		if (zone->uz_flags & UMA_ZFLAG_OFFPAGE)
+			slab = hash_sfind(&zone->uz_hash, mem);
+		else {
+			mem += zone->uz_pgoff;
+			slab = (uma_slab_t)mem;
+		}
+	} else {
+		slab = (uma_slab_t)udata;
+	}
+
+	/* Do we need to remove from any lists? */
+	if (slab->us_freecount+1 == zone->uz_ipers) {
+		LIST_REMOVE(slab, us_link);
+		LIST_INSERT_HEAD(&zone->uz_free_slab, slab, us_link);
+	} else if (slab->us_freecount == 0) {
+		LIST_REMOVE(slab, us_link);
+		LIST_INSERT_HEAD(&zone->uz_part_slab, slab, us_link);
+	}
+
+	/* Slab management stuff */	
+	freei = ((unsigned long)item - (unsigned long)slab->us_data)
+		/ zone->uz_rsize;
+#ifdef INVARIANTS
+	if (((freei * zone->uz_rsize) + slab->us_data) != item)
+		panic("zone: %s(%p) slab %p freed address %p unaligned.\n", 
+		    zone->uz_name, zone, slab, item);
+	if (freei >= zone->uz_ipers)
+		panic("zone: %s(%p) slab %p freelist %i out of range 0-%d\n",
+		    zone->uz_name, zone, slab, freei, zone->uz_ipers-1);
+
+	if (slab->us_freelist[freei] != 255) {
+		printf("Slab at %p, freei %d = %d.\n",
+		    slab, freei, slab->us_freelist[freei]);
+		panic("Duplicate free of item %p from zone %p(%s)\n",
+		    item, zone, zone->uz_name);
+	}
+#endif
+	slab->us_freelist[freei] = slab->us_firstfree;
+	slab->us_firstfree = freei;
+	slab->us_freecount++;
+
+	/* Zone statistics */
+	zone->uz_free++;
+
+	ZONE_UNLOCK(zone);
+
+	if (!skip && zone->uz_dtor)
+		zone->uz_dtor(item, zone->uz_size, udata);
+}
+
+/* See uma.h */
+void
+uma_zone_set_freef(uma_zone_t zone, uma_free freef)
+{
+	ZONE_LOCK(zone);
+
+	zone->uz_freef = freef;
+
+	ZONE_UNLOCK(zone);
+}
+
+/* See uma.h */
+void
+uma_zone_set_allocf(uma_zone_t zone, uma_alloc allocf)
+{
+	ZONE_LOCK(zone);
+
+	zone->uz_flags |= UMA_ZFLAG_PRIVALLOC;
+	zone->uz_allocf = allocf;
+
+	ZONE_UNLOCK(zone);
+}
+
+/* See uma.h */
+int
+uma_zone_set_obj(uma_zone_t zone, struct vm_object *obj, int count)
+{
+	int pages;
+	vm_offset_t kva;
+
+	ZONE_LOCK(zone);
+	mtx_lock(&Giant);
+
+	zone->uz_obj = obj;
+	pages = count / zone->uz_ipers;
+
+	if (pages * zone->uz_ipers < count)
+		pages++;
+	zone->uz_kva = NULL;
+	ZONE_UNLOCK(zone);
+	kva = kmem_alloc_pageable(kernel_map, pages * UMA_SLAB_SIZE);
+	ZONE_LOCK(zone);
+
+	zone->uz_kva = kva;
+
+	if (zone->uz_kva == 0) {
+		ZONE_UNLOCK(zone);
+		return (0);
+	}
+
+	zone->uz_maxpages = pages;
+
+	if (zone->uz_obj == NULL)
+		zone->uz_obj = vm_object_allocate(OBJT_DEFAULT,
+		    zone->uz_maxpages);
+	else 
+		_vm_object_allocate(OBJT_DEFAULT,
+		    zone->uz_maxpages, zone->uz_obj);
+
+	zone->uz_allocf = obj_alloc;
+	zone->uz_flags |= UMA_ZFLAG_NOFREE | UMA_ZFLAG_PRIVALLOC;
+
+	mtx_unlock(&Giant);
+	ZONE_UNLOCK(zone);
+
+	return (1);
+}
+
+/* See uma.h */
+void
+uma_prealloc(uma_zone_t zone, int items)
+{
+	int slabs;
+	uma_slab_t slab;
+
+	ZONE_LOCK(zone);
+	slabs = items / zone->uz_ipers;
+	if (slabs * zone->uz_ipers < items)
+		slabs++;
+
+	while (slabs > 0) {
+		slab = slab_zalloc(zone, M_WAITOK);
+		LIST_INSERT_HEAD(&zone->uz_free_slab, slab, us_link);
+		slabs--;
+	}
+	ZONE_UNLOCK(zone);
+}
+
+/* See uma.h */
+void
+uma_reclaim(void)
+{
+	/*
+	 * You might think that the delay below would improve performance since
+	 * the allocator will give away memory that it may ask for immediately.
+	 * Really, it makes things worse, since cpu cycles are so much cheaper
+	 * than disk activity.
+	 */
+#if 0
+	static struct timeval tv = {0};
+	struct timeval now;
+	getmicrouptime(&now);
+	if (now.tv_sec > tv.tv_sec + 30)
+		tv = now;
+	else
+		return;
+#endif
+#ifdef UMA_DEBUG
+	printf("UMA: vm asked us to release pages!\n");
+#endif
+	zone_foreach(zone_drain);
+
+	/*
+	 * Some slabs may have been freed but this zone will be visited early
+	 * we visit again so that we can free pages that are empty once other
+	 * zones are drained.  We have to do the same for buckets.
+	 */
+	zone_drain(slabzone);
+	zone_drain(bucketzone);
+}
+
+void *
+uma_large_malloc(int size, int wait)
+{
+	void *mem;
+	uma_slab_t slab;
+	u_int8_t flags;
+
+	slab = uma_zalloc_internal(slabzone, NULL, wait, NULL, -1);
+	if (slab == NULL)
+		return (NULL);
+
+	mem = page_alloc(NULL, size, &flags, wait);
+	if (mem) {
+		slab->us_data = mem;
+		slab->us_flags = flags | UMA_SLAB_MALLOC;
+		slab->us_size = size;
+		UMA_HASH_INSERT(mallochash, slab, mem);
+	} else {
+		uma_zfree_internal(slabzone, slab, NULL, 0);
+	}
+
+
+	return (mem);
+}
+
+void
+uma_large_free(uma_slab_t slab)
+{
+	UMA_HASH_REMOVE(mallochash, slab, slab->us_data);
+	page_free(slab->us_data, slab->us_size, slab->us_flags);
+	uma_zfree_internal(slabzone, slab, NULL, 0);
+}
+
+void
+uma_print_stats(void)
+{
+	zone_foreach(uma_print_zone);
+}
+
+void
+uma_print_zone(uma_zone_t zone)
+{
+	printf("%s(%p) size %d(%d) flags %d ipers %d ppera %d out %d free %d\n",
+	    zone->uz_name, zone, zone->uz_size, zone->uz_rsize, zone->uz_flags,
+	    zone->uz_ipers, zone->uz_ppera,
+	    (zone->uz_ipers * zone->uz_pages) - zone->uz_free, zone->uz_free);
+}
+
+/*
+ * Sysctl handler for vm.zone 
+ *
+ * stolen from vm_zone.c
+ */
+static int
+sysctl_vm_zone(SYSCTL_HANDLER_ARGS)
+{
+	int error, len, cnt;
+	const int linesize = 128;	/* conservative */
+	int totalfree;
+	char *tmpbuf, *offset;
+	uma_zone_t z;
+	char *p;
+
+	cnt = 0;
+	LIST_FOREACH(z, &uma_zones, uz_link)
+		cnt++;
+	MALLOC(tmpbuf, char *, (cnt == 0 ? 1 : cnt) * linesize,
+			M_TEMP, M_WAITOK);
+	len = snprintf(tmpbuf, linesize,
+	    "\nITEM            SIZE     LIMIT     USED    FREE  REQUESTS\n\n");
+	if (cnt == 0)
+		tmpbuf[len - 1] = '\0';
+	error = SYSCTL_OUT(req, tmpbuf, cnt == 0 ? len-1 : len);
+	if (error || cnt == 0)
+		goto out;
+	offset = tmpbuf;
+	LIST_FOREACH(z, &uma_zones, uz_link) {
+		if (cnt == 0)	/* list may have changed size */
+			break;
+		ZONE_LOCK(z);
+		totalfree = z->uz_free + z->uz_cachefree;
+		len = snprintf(offset, linesize,
+		    "%-12.12s  %6.6u, %8.8u, %6.6u, %6.6u, %8.8llu\n",
+		    z->uz_name, z->uz_size,
+		    z->uz_maxpages * z->uz_ipers,
+		    (z->uz_ipers * (z->uz_pages / z->uz_ppera)) - totalfree,
+		    totalfree,
+		    (unsigned long long)z->uz_allocs);
+		ZONE_UNLOCK(z);
+		for (p = offset + 12; p > offset && *p == ' '; --p)
+			/* nothing */ ;
+		p[1] = ':';
+		cnt--;
+		offset += len;
+	}
+	*offset++ = '\0';
+	error = SYSCTL_OUT(req, tmpbuf, offset - tmpbuf);
+out:
+	FREE(tmpbuf, M_TEMP);
+	return (error);
+}