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Revision 1.196, Tue Jun 5 22:28:11 2012 UTC (2 years, 1 month ago) by jym
Branch: MAIN
Changes since 1.195: +23 -15 lines

As pool reclaiming is unlikely to happen at interrupt or softint
context, re-enable the portion of code that allows invalidation of CPU-bound
pool caches.

Two reasons:
- CPU cached objects being invalidated, the probability of fetching an
obsolete object from the pool_cache(9) is greatly reduced. This speeds up
pool_cache_get() quite a bit as it does not have to keep destroying objects
until it finds an updated one when an invalidation is in progress.

- for situations where we have to ensure that no obsolete object remains
after a state transition (canonical example: pmap mappings between Xen VM
restoration), invalidating all pool_cache(9) is the safest way to go.

As it uses xcall(9) to broadcast the execution of pool_cache_transfer(),
pool_cache_invalidate() cannot be called from interrupt or softint context
(scheduling a xcall(9) can put a LWP to sleep).

pool_cache_xcall() => pool_cache_transfer() to reflect its use.

Invalidation being a costly process (1000s objects may be destroyed),
all places where pool_cache_invalidate() may be called from
interrupt/softint context will now get caught by the proper KASSERT(), and
fixed. Ping me when you see one.

Tested under i386 and amd64 by running ATF suite within 64MiB HVM
domains (tried triggering pgdaemon a few times).

No objection on tech-kern@.

XXX a similar fix has to be pulled up to NetBSD-6, but with a more
conservative approach.

See http://mail-index.netbsd.org/tech-kern/2012/05/29/msg013245.html

/*	$NetBSD: subr_pool.c,v 1.196 2012/06/05 22:28:11 jym Exp $	*/

/*-
 * Copyright (c) 1997, 1999, 2000, 2002, 2007, 2008, 2010
 *     The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Paul Kranenburg; by Jason R. Thorpe of the Numerical Aerospace
 * Simulation Facility, NASA Ames Research Center, and by Andrew Doran.
 *
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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>
__KERNEL_RCSID(0, "$NetBSD: subr_pool.c,v 1.196 2012/06/05 22:28:11 jym Exp $");

#include "opt_ddb.h"
#include "opt_lockdebug.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bitops.h>
#include <sys/proc.h>
#include <sys/errno.h>
#include <sys/kernel.h>
#include <sys/vmem.h>
#include <sys/pool.h>
#include <sys/syslog.h>
#include <sys/debug.h>
#include <sys/lockdebug.h>
#include <sys/xcall.h>
#include <sys/cpu.h>
#include <sys/atomic.h>

#include <uvm/uvm_extern.h>

/*
 * Pool resource management utility.
 *
 * Memory is allocated in pages which are split into pieces according to
 * the pool item size. Each page is kept on one of three lists in the
 * pool structure: `pr_emptypages', `pr_fullpages' and `pr_partpages',
 * for empty, full and partially-full pages respectively. The individual
 * pool items are on a linked list headed by `ph_itemlist' in each page
 * header. The memory for building the page list is either taken from
 * the allocated pages themselves (for small pool items) or taken from
 * an internal pool of page headers (`phpool').
 */

/* List of all pools */
static TAILQ_HEAD(, pool) pool_head = TAILQ_HEAD_INITIALIZER(pool_head);

/* Private pool for page header structures */
#define	PHPOOL_MAX	8
static struct pool phpool[PHPOOL_MAX];
#define	PHPOOL_FREELIST_NELEM(idx) \
	(((idx) == 0) ? 0 : BITMAP_SIZE * (1 << (idx)))

#ifdef POOL_SUBPAGE
/* Pool of subpages for use by normal pools. */
static struct pool psppool;
#endif

static void *pool_page_alloc_meta(struct pool *, int);
static void pool_page_free_meta(struct pool *, void *);

/* allocator for pool metadata */
struct pool_allocator pool_allocator_meta = {
	.pa_alloc = pool_page_alloc_meta,
	.pa_free = pool_page_free_meta,
	.pa_pagesz = 0
};

/* # of seconds to retain page after last use */
int pool_inactive_time = 10;

/* Next candidate for drainage (see pool_drain()) */
static struct pool	*drainpp;

/* This lock protects both pool_head and drainpp. */
static kmutex_t pool_head_lock;
static kcondvar_t pool_busy;

/* This lock protects initialization of a potentially shared pool allocator */
static kmutex_t pool_allocator_lock;

typedef uint32_t pool_item_bitmap_t;
#define	BITMAP_SIZE	(CHAR_BIT * sizeof(pool_item_bitmap_t))
#define	BITMAP_MASK	(BITMAP_SIZE - 1)

struct pool_item_header {
	/* Page headers */
	LIST_ENTRY(pool_item_header)
				ph_pagelist;	/* pool page list */
	SPLAY_ENTRY(pool_item_header)
				ph_node;	/* Off-page page headers */
	void *			ph_page;	/* this page's address */
	uint32_t		ph_time;	/* last referenced */
	uint16_t		ph_nmissing;	/* # of chunks in use */
	uint16_t		ph_off;		/* start offset in page */
	union {
		/* !PR_NOTOUCH */
		struct {
			LIST_HEAD(, pool_item)
				phu_itemlist;	/* chunk list for this page */
		} phu_normal;
		/* PR_NOTOUCH */
		struct {
			pool_item_bitmap_t phu_bitmap[1];
		} phu_notouch;
	} ph_u;
};
#define	ph_itemlist	ph_u.phu_normal.phu_itemlist
#define	ph_bitmap	ph_u.phu_notouch.phu_bitmap

struct pool_item {
#ifdef DIAGNOSTIC
	u_int pi_magic;
#endif
#define	PI_MAGIC 0xdeaddeadU
	/* Other entries use only this list entry */
	LIST_ENTRY(pool_item)	pi_list;
};

#define	POOL_NEEDS_CATCHUP(pp)						\
	((pp)->pr_nitems < (pp)->pr_minitems)

/*
 * Pool cache management.
 *
 * Pool caches provide a way for constructed objects to be cached by the
 * pool subsystem.  This can lead to performance improvements by avoiding
 * needless object construction/destruction; it is deferred until absolutely
 * necessary.
 *
 * Caches are grouped into cache groups.  Each cache group references up
 * to PCG_NUMOBJECTS constructed objects.  When a cache allocates an
 * object from the pool, it calls the object's constructor and places it
 * into a cache group.  When a cache group frees an object back to the
 * pool, it first calls the object's destructor.  This allows the object
 * to persist in constructed form while freed to the cache.
 *
 * The pool references each cache, so that when a pool is drained by the
 * pagedaemon, it can drain each individual cache as well.  Each time a
 * cache is drained, the most idle cache group is freed to the pool in
 * its entirety.
 *
 * Pool caches are layed on top of pools.  By layering them, we can avoid
 * the complexity of cache management for pools which would not benefit
 * from it.
 */

static struct pool pcg_normal_pool;
static struct pool pcg_large_pool;
static struct pool cache_pool;
static struct pool cache_cpu_pool;

pool_cache_t pnbuf_cache;	/* pathname buffer cache */

/* List of all caches. */
TAILQ_HEAD(,pool_cache) pool_cache_head =
    TAILQ_HEAD_INITIALIZER(pool_cache_head);

int pool_cache_disable;		/* global disable for caching */
static const pcg_t pcg_dummy;	/* zero sized: always empty, yet always full */

static bool	pool_cache_put_slow(pool_cache_cpu_t *, int,
				    void *);
static bool	pool_cache_get_slow(pool_cache_cpu_t *, int,
				    void **, paddr_t *, int);
static void	pool_cache_cpu_init1(struct cpu_info *, pool_cache_t);
static void	pool_cache_invalidate_groups(pool_cache_t, pcg_t *);
static void	pool_cache_invalidate_cpu(pool_cache_t, u_int);
static void	pool_cache_transfer(pool_cache_t);

static int	pool_catchup(struct pool *);
static void	pool_prime_page(struct pool *, void *,
		    struct pool_item_header *);
static void	pool_update_curpage(struct pool *);

static int	pool_grow(struct pool *, int);
static void	*pool_allocator_alloc(struct pool *, int);
static void	pool_allocator_free(struct pool *, void *);

static void pool_print_pagelist(struct pool *, struct pool_pagelist *,
	void (*)(const char *, ...));
static void pool_print1(struct pool *, const char *,
	void (*)(const char *, ...));

static int pool_chk_page(struct pool *, const char *,
			 struct pool_item_header *);

static inline unsigned int
pr_item_notouch_index(const struct pool *pp, const struct pool_item_header *ph,
    const void *v)
{
	const char *cp = v;
	unsigned int idx;

	KASSERT(pp->pr_roflags & PR_NOTOUCH);
	idx = (cp - (char *)ph->ph_page - ph->ph_off) / pp->pr_size;
	KASSERT(idx < pp->pr_itemsperpage);
	return idx;
}

static inline void
pr_item_notouch_put(const struct pool *pp, struct pool_item_header *ph,
    void *obj)
{
	unsigned int idx = pr_item_notouch_index(pp, ph, obj);
	pool_item_bitmap_t *bitmap = ph->ph_bitmap + (idx / BITMAP_SIZE);
	pool_item_bitmap_t mask = 1 << (idx & BITMAP_MASK);

	KASSERT((*bitmap & mask) == 0);
	*bitmap |= mask;
}

static inline void *
pr_item_notouch_get(const struct pool *pp, struct pool_item_header *ph)
{
	pool_item_bitmap_t *bitmap = ph->ph_bitmap;
	unsigned int idx;
	int i;

	for (i = 0; ; i++) {
		int bit;

		KASSERT((i * BITMAP_SIZE) < pp->pr_itemsperpage);
		bit = ffs32(bitmap[i]);
		if (bit) {
			pool_item_bitmap_t mask;

			bit--;
			idx = (i * BITMAP_SIZE) + bit;
			mask = 1 << bit;
			KASSERT((bitmap[i] & mask) != 0);
			bitmap[i] &= ~mask;
			break;
		}
	}
	KASSERT(idx < pp->pr_itemsperpage);
	return (char *)ph->ph_page + ph->ph_off + idx * pp->pr_size;
}

static inline void
pr_item_notouch_init(const struct pool *pp, struct pool_item_header *ph)
{
	pool_item_bitmap_t *bitmap = ph->ph_bitmap;
	const int n = howmany(pp->pr_itemsperpage, BITMAP_SIZE);
	int i;

	for (i = 0; i < n; i++) {
		bitmap[i] = (pool_item_bitmap_t)-1;
	}
}

static inline int
phtree_compare(struct pool_item_header *a, struct pool_item_header *b)
{

	/*
	 * we consider pool_item_header with smaller ph_page bigger.
	 * (this unnatural ordering is for the benefit of pr_find_pagehead.)
	 */

	if (a->ph_page < b->ph_page)
		return (1);
	else if (a->ph_page > b->ph_page)
		return (-1);
	else
		return (0);
}

SPLAY_PROTOTYPE(phtree, pool_item_header, ph_node, phtree_compare);
SPLAY_GENERATE(phtree, pool_item_header, ph_node, phtree_compare);

static inline struct pool_item_header *
pr_find_pagehead_noalign(struct pool *pp, void *v)
{
	struct pool_item_header *ph, tmp;

	tmp.ph_page = (void *)(uintptr_t)v;
	ph = SPLAY_FIND(phtree, &pp->pr_phtree, &tmp);
	if (ph == NULL) {
		ph = SPLAY_ROOT(&pp->pr_phtree);
		if (ph != NULL && phtree_compare(&tmp, ph) >= 0) {
			ph = SPLAY_NEXT(phtree, &pp->pr_phtree, ph);
		}
		KASSERT(ph == NULL || phtree_compare(&tmp, ph) < 0);
	}

	return ph;
}

/*
 * Return the pool page header based on item address.
 */
static inline struct pool_item_header *
pr_find_pagehead(struct pool *pp, void *v)
{
	struct pool_item_header *ph, tmp;

	if ((pp->pr_roflags & PR_NOALIGN) != 0) {
		ph = pr_find_pagehead_noalign(pp, v);
	} else {
		void *page =
		    (void *)((uintptr_t)v & pp->pr_alloc->pa_pagemask);

		if ((pp->pr_roflags & PR_PHINPAGE) != 0) {
			ph = (struct pool_item_header *)((char *)page + pp->pr_phoffset);
		} else {
			tmp.ph_page = page;
			ph = SPLAY_FIND(phtree, &pp->pr_phtree, &tmp);
		}
	}

	KASSERT(ph == NULL || ((pp->pr_roflags & PR_PHINPAGE) != 0) ||
	    ((char *)ph->ph_page <= (char *)v &&
	    (char *)v < (char *)ph->ph_page + pp->pr_alloc->pa_pagesz));
	return ph;
}

static void
pr_pagelist_free(struct pool *pp, struct pool_pagelist *pq)
{
	struct pool_item_header *ph;

	while ((ph = LIST_FIRST(pq)) != NULL) {
		LIST_REMOVE(ph, ph_pagelist);
		pool_allocator_free(pp, ph->ph_page);
		if ((pp->pr_roflags & PR_PHINPAGE) == 0)
			pool_put(pp->pr_phpool, ph);
	}
}

/*
 * Remove a page from the pool.
 */
static inline void
pr_rmpage(struct pool *pp, struct pool_item_header *ph,
     struct pool_pagelist *pq)
{

	KASSERT(mutex_owned(&pp->pr_lock));

	/*
	 * If the page was idle, decrement the idle page count.
	 */
	if (ph->ph_nmissing == 0) {
#ifdef DIAGNOSTIC
		if (pp->pr_nidle == 0)
			panic("pr_rmpage: nidle inconsistent");
		if (pp->pr_nitems < pp->pr_itemsperpage)
			panic("pr_rmpage: nitems inconsistent");
#endif
		pp->pr_nidle--;
	}

	pp->pr_nitems -= pp->pr_itemsperpage;

	/*
	 * Unlink the page from the pool and queue it for release.
	 */
	LIST_REMOVE(ph, ph_pagelist);
	if ((pp->pr_roflags & PR_PHINPAGE) == 0)
		SPLAY_REMOVE(phtree, &pp->pr_phtree, ph);
	LIST_INSERT_HEAD(pq, ph, ph_pagelist);

	pp->pr_npages--;
	pp->pr_npagefree++;

	pool_update_curpage(pp);
}

/*
 * Initialize all the pools listed in the "pools" link set.
 */
void
pool_subsystem_init(void)
{
	size_t size;
	int idx;

	mutex_init(&pool_head_lock, MUTEX_DEFAULT, IPL_NONE);
	mutex_init(&pool_allocator_lock, MUTEX_DEFAULT, IPL_NONE);
	cv_init(&pool_busy, "poolbusy");

	/*
	 * Initialize private page header pool and cache magazine pool if we
	 * haven't done so yet.
	 */
	for (idx = 0; idx < PHPOOL_MAX; idx++) {
		static char phpool_names[PHPOOL_MAX][6+1+6+1];
		int nelem;
		size_t sz;

		nelem = PHPOOL_FREELIST_NELEM(idx);
		snprintf(phpool_names[idx], sizeof(phpool_names[idx]),
		    "phpool-%d", nelem);
		sz = sizeof(struct pool_item_header);
		if (nelem) {
			sz = offsetof(struct pool_item_header,
			    ph_bitmap[howmany(nelem, BITMAP_SIZE)]);
		}
		pool_init(&phpool[idx], sz, 0, 0, 0,
		    phpool_names[idx], &pool_allocator_meta, IPL_VM);
	}
#ifdef POOL_SUBPAGE
	pool_init(&psppool, POOL_SUBPAGE, POOL_SUBPAGE, 0,
	    PR_RECURSIVE, "psppool", &pool_allocator_meta, IPL_VM);
#endif

	size = sizeof(pcg_t) +
	    (PCG_NOBJECTS_NORMAL - 1) * sizeof(pcgpair_t);
	pool_init(&pcg_normal_pool, size, coherency_unit, 0, 0,
	    "pcgnormal", &pool_allocator_meta, IPL_VM);

	size = sizeof(pcg_t) +
	    (PCG_NOBJECTS_LARGE - 1) * sizeof(pcgpair_t);
	pool_init(&pcg_large_pool, size, coherency_unit, 0, 0,
	    "pcglarge", &pool_allocator_meta, IPL_VM);

	pool_init(&cache_pool, sizeof(struct pool_cache), coherency_unit,
	    0, 0, "pcache", &pool_allocator_meta, IPL_NONE);

	pool_init(&cache_cpu_pool, sizeof(pool_cache_cpu_t), coherency_unit,
	    0, 0, "pcachecpu", &pool_allocator_meta, IPL_NONE);
}

/*
 * Initialize the given pool resource structure.
 *
 * We export this routine to allow other kernel parts to declare
 * static pools that must be initialized before kmem(9) is available.
 */
void
pool_init(struct pool *pp, size_t size, u_int align, u_int ioff, int flags,
    const char *wchan, struct pool_allocator *palloc, int ipl)
{
	struct pool *pp1;
	size_t trysize, phsize;
	int off, slack;

#ifdef DEBUG
	/*
	 * Check that the pool hasn't already been initialised and
	 * added to the list of all pools.
	 */
	TAILQ_FOREACH(pp1, &pool_head, pr_poollist) {
		if (pp == pp1)
			panic("pool_init: pool %s already initialised",
			    wchan);
	}
#endif

	if (palloc == NULL)
		palloc = &pool_allocator_kmem;
#ifdef POOL_SUBPAGE
	if (size > palloc->pa_pagesz) {
		if (palloc == &pool_allocator_kmem)
			palloc = &pool_allocator_kmem_fullpage;
		else if (palloc == &pool_allocator_nointr)
			palloc = &pool_allocator_nointr_fullpage;
	}		
#endif /* POOL_SUBPAGE */
	if (!cold)
		mutex_enter(&pool_allocator_lock);
	if (palloc->pa_refcnt++ == 0) {
		if (palloc->pa_pagesz == 0)
			palloc->pa_pagesz = PAGE_SIZE;

		TAILQ_INIT(&palloc->pa_list);

		mutex_init(&palloc->pa_lock, MUTEX_DEFAULT, IPL_VM);
		palloc->pa_pagemask = ~(palloc->pa_pagesz - 1);
		palloc->pa_pageshift = ffs(palloc->pa_pagesz) - 1;
	}
	if (!cold)
		mutex_exit(&pool_allocator_lock);

	if (align == 0)
		align = ALIGN(1);

	if ((flags & PR_NOTOUCH) == 0 && size < sizeof(struct pool_item))
		size = sizeof(struct pool_item);

	size = roundup(size, align);
#ifdef DIAGNOSTIC
	if (size > palloc->pa_pagesz)
		panic("pool_init: pool item size (%zu) too large", size);
#endif

	/*
	 * Initialize the pool structure.
	 */
	LIST_INIT(&pp->pr_emptypages);
	LIST_INIT(&pp->pr_fullpages);
	LIST_INIT(&pp->pr_partpages);
	pp->pr_cache = NULL;
	pp->pr_curpage = NULL;
	pp->pr_npages = 0;
	pp->pr_minitems = 0;
	pp->pr_minpages = 0;
	pp->pr_maxpages = UINT_MAX;
	pp->pr_roflags = flags;
	pp->pr_flags = 0;
	pp->pr_size = size;
	pp->pr_align = align;
	pp->pr_wchan = wchan;
	pp->pr_alloc = palloc;
	pp->pr_nitems = 0;
	pp->pr_nout = 0;
	pp->pr_hardlimit = UINT_MAX;
	pp->pr_hardlimit_warning = NULL;
	pp->pr_hardlimit_ratecap.tv_sec = 0;
	pp->pr_hardlimit_ratecap.tv_usec = 0;
	pp->pr_hardlimit_warning_last.tv_sec = 0;
	pp->pr_hardlimit_warning_last.tv_usec = 0;
	pp->pr_drain_hook = NULL;
	pp->pr_drain_hook_arg = NULL;
	pp->pr_freecheck = NULL;

	/*
	 * Decide whether to put the page header off page to avoid
	 * wasting too large a part of the page or too big item.
	 * Off-page page headers go on a hash table, so we can match
	 * a returned item with its header based on the page address.
	 * We use 1/16 of the page size and about 8 times of the item
	 * size as the threshold (XXX: tune)
	 *
	 * However, we'll put the header into the page if we can put
	 * it without wasting any items.
	 *
	 * Silently enforce `0 <= ioff < align'.
	 */
	pp->pr_itemoffset = ioff %= align;
	/* See the comment below about reserved bytes. */
	trysize = palloc->pa_pagesz - ((align - ioff) % align);
	phsize = ALIGN(sizeof(struct pool_item_header));
	if ((pp->pr_roflags & (PR_NOTOUCH | PR_NOALIGN)) == 0 &&
	    (pp->pr_size < MIN(palloc->pa_pagesz / 16, phsize << 3) ||
	    trysize / pp->pr_size == (trysize - phsize) / pp->pr_size)) {
		/* Use the end of the page for the page header */
		pp->pr_roflags |= PR_PHINPAGE;
		pp->pr_phoffset = off = palloc->pa_pagesz - phsize;
	} else {
		/* The page header will be taken from our page header pool */
		pp->pr_phoffset = 0;
		off = palloc->pa_pagesz;
		SPLAY_INIT(&pp->pr_phtree);
	}

	/*
	 * Alignment is to take place at `ioff' within the item. This means
	 * we must reserve up to `align - 1' bytes on the page to allow
	 * appropriate positioning of each item.
	 */
	pp->pr_itemsperpage = (off - ((align - ioff) % align)) / pp->pr_size;
	KASSERT(pp->pr_itemsperpage != 0);
	if ((pp->pr_roflags & PR_NOTOUCH)) {
		int idx;

		for (idx = 0; pp->pr_itemsperpage > PHPOOL_FREELIST_NELEM(idx);
		    idx++) {
			/* nothing */
		}
		if (idx >= PHPOOL_MAX) {
			/*
			 * if you see this panic, consider to tweak
			 * PHPOOL_MAX and PHPOOL_FREELIST_NELEM.
			 */
			panic("%s: too large itemsperpage(%d) for PR_NOTOUCH",
			    pp->pr_wchan, pp->pr_itemsperpage);
		}
		pp->pr_phpool = &phpool[idx];
	} else if ((pp->pr_roflags & PR_PHINPAGE) == 0) {
		pp->pr_phpool = &phpool[0];
	}
#if defined(DIAGNOSTIC)
	else {
		pp->pr_phpool = NULL;
	}
#endif

	/*
	 * Use the slack between the chunks and the page header
	 * for "cache coloring".
	 */
	slack = off - pp->pr_itemsperpage * pp->pr_size;
	pp->pr_maxcolor = (slack / align) * align;
	pp->pr_curcolor = 0;

	pp->pr_nget = 0;
	pp->pr_nfail = 0;
	pp->pr_nput = 0;
	pp->pr_npagealloc = 0;
	pp->pr_npagefree = 0;
	pp->pr_hiwat = 0;
	pp->pr_nidle = 0;
	pp->pr_refcnt = 0;

	mutex_init(&pp->pr_lock, MUTEX_DEFAULT, ipl);
	cv_init(&pp->pr_cv, wchan);
	pp->pr_ipl = ipl;

	/* Insert into the list of all pools. */
	if (!cold)
		mutex_enter(&pool_head_lock);
	TAILQ_FOREACH(pp1, &pool_head, pr_poollist) {
		if (strcmp(pp1->pr_wchan, pp->pr_wchan) > 0)
			break;
	}
	if (pp1 == NULL)
		TAILQ_INSERT_TAIL(&pool_head, pp, pr_poollist);
	else
		TAILQ_INSERT_BEFORE(pp1, pp, pr_poollist);
	if (!cold)
		mutex_exit(&pool_head_lock);

	/* Insert this into the list of pools using this allocator. */
	if (!cold)
		mutex_enter(&palloc->pa_lock);
	TAILQ_INSERT_TAIL(&palloc->pa_list, pp, pr_alloc_list);
	if (!cold)
		mutex_exit(&palloc->pa_lock);
}

/*
 * De-commision a pool resource.
 */
void
pool_destroy(struct pool *pp)
{
	struct pool_pagelist pq;
	struct pool_item_header *ph;

	/* Remove from global pool list */
	mutex_enter(&pool_head_lock);
	while (pp->pr_refcnt != 0)
		cv_wait(&pool_busy, &pool_head_lock);
	TAILQ_REMOVE(&pool_head, pp, pr_poollist);
	if (drainpp == pp)
		drainpp = NULL;
	mutex_exit(&pool_head_lock);

	/* Remove this pool from its allocator's list of pools. */
	mutex_enter(&pp->pr_alloc->pa_lock);
	TAILQ_REMOVE(&pp->pr_alloc->pa_list, pp, pr_alloc_list);
	mutex_exit(&pp->pr_alloc->pa_lock);

	mutex_enter(&pool_allocator_lock);
	if (--pp->pr_alloc->pa_refcnt == 0)
		mutex_destroy(&pp->pr_alloc->pa_lock);
	mutex_exit(&pool_allocator_lock);

	mutex_enter(&pp->pr_lock);

	KASSERT(pp->pr_cache == NULL);

#ifdef DIAGNOSTIC
	if (pp->pr_nout != 0) {
		panic("pool_destroy: pool busy: still out: %u",
		    pp->pr_nout);
	}
#endif

	KASSERT(LIST_EMPTY(&pp->pr_fullpages));
	KASSERT(LIST_EMPTY(&pp->pr_partpages));

	/* Remove all pages */
	LIST_INIT(&pq);
	while ((ph = LIST_FIRST(&pp->pr_emptypages)) != NULL)
		pr_rmpage(pp, ph, &pq);

	mutex_exit(&pp->pr_lock);

	pr_pagelist_free(pp, &pq);
	cv_destroy(&pp->pr_cv);
	mutex_destroy(&pp->pr_lock);
}

void
pool_set_drain_hook(struct pool *pp, void (*fn)(void *, int), void *arg)
{

	/* XXX no locking -- must be used just after pool_init() */
#ifdef DIAGNOSTIC
	if (pp->pr_drain_hook != NULL)
		panic("pool_set_drain_hook(%s): already set", pp->pr_wchan);
#endif
	pp->pr_drain_hook = fn;
	pp->pr_drain_hook_arg = arg;
}

static struct pool_item_header *
pool_alloc_item_header(struct pool *pp, void *storage, int flags)
{
	struct pool_item_header *ph;

	if ((pp->pr_roflags & PR_PHINPAGE) != 0)
		ph = (struct pool_item_header *) ((char *)storage + pp->pr_phoffset);
	else
		ph = pool_get(pp->pr_phpool, flags);

	return (ph);
}

/*
 * Grab an item from the pool.
 */
void *
pool_get(struct pool *pp, int flags)
{
	struct pool_item *pi;
	struct pool_item_header *ph;
	void *v;

#ifdef DIAGNOSTIC
	if (pp->pr_itemsperpage == 0)
		panic("pool_get: pool '%s': pr_itemsperpage is zero, "
		    "pool not initialized?", pp->pr_wchan);
	if ((cpu_intr_p() || cpu_softintr_p()) && pp->pr_ipl == IPL_NONE &&
	    !cold && panicstr == NULL)
		panic("pool '%s' is IPL_NONE, but called from "
		    "interrupt context\n", pp->pr_wchan);
#endif
	if (flags & PR_WAITOK) {
		ASSERT_SLEEPABLE();
	}

	mutex_enter(&pp->pr_lock);
 startover:
	/*
	 * Check to see if we've reached the hard limit.  If we have,
	 * and we can wait, then wait until an item has been returned to
	 * the pool.
	 */
#ifdef DIAGNOSTIC
	if (__predict_false(pp->pr_nout > pp->pr_hardlimit)) {
		mutex_exit(&pp->pr_lock);
		panic("pool_get: %s: crossed hard limit", pp->pr_wchan);
	}
#endif
	if (__predict_false(pp->pr_nout == pp->pr_hardlimit)) {
		if (pp->pr_drain_hook != NULL) {
			/*
			 * Since the drain hook is going to free things
			 * back to the pool, unlock, call the hook, re-lock,
			 * and check the hardlimit condition again.
			 */
			mutex_exit(&pp->pr_lock);
			(*pp->pr_drain_hook)(pp->pr_drain_hook_arg, flags);
			mutex_enter(&pp->pr_lock);
			if (pp->pr_nout < pp->pr_hardlimit)
				goto startover;
		}

		if ((flags & PR_WAITOK) && !(flags & PR_LIMITFAIL)) {
			/*
			 * XXX: A warning isn't logged in this case.  Should
			 * it be?
			 */
			pp->pr_flags |= PR_WANTED;
			cv_wait(&pp->pr_cv, &pp->pr_lock);
			goto startover;
		}

		/*
		 * Log a message that the hard limit has been hit.
		 */
		if (pp->pr_hardlimit_warning != NULL &&
		    ratecheck(&pp->pr_hardlimit_warning_last,
			      &pp->pr_hardlimit_ratecap))
			log(LOG_ERR, "%s\n", pp->pr_hardlimit_warning);

		pp->pr_nfail++;

		mutex_exit(&pp->pr_lock);
		return (NULL);
	}

	/*
	 * The convention we use is that if `curpage' is not NULL, then
	 * it points at a non-empty bucket. In particular, `curpage'
	 * never points at a page header which has PR_PHINPAGE set and
	 * has no items in its bucket.
	 */
	if ((ph = pp->pr_curpage) == NULL) {
		int error;

#ifdef DIAGNOSTIC
		if (pp->pr_nitems != 0) {
			mutex_exit(&pp->pr_lock);
			printf("pool_get: %s: curpage NULL, nitems %u\n",
			    pp->pr_wchan, pp->pr_nitems);
			panic("pool_get: nitems inconsistent");
		}
#endif

		/*
		 * Call the back-end page allocator for more memory.
		 * Release the pool lock, as the back-end page allocator
		 * may block.
		 */
		error = pool_grow(pp, flags);
		if (error != 0) {
			/*
			 * We were unable to allocate a page or item
			 * header, but we released the lock during
			 * allocation, so perhaps items were freed
			 * back to the pool.  Check for this case.
			 */
			if (pp->pr_curpage != NULL)
				goto startover;

			pp->pr_nfail++;
			mutex_exit(&pp->pr_lock);
			return (NULL);
		}

		/* Start the allocation process over. */
		goto startover;
	}
	if (pp->pr_roflags & PR_NOTOUCH) {
#ifdef DIAGNOSTIC
		if (__predict_false(ph->ph_nmissing == pp->pr_itemsperpage)) {
			mutex_exit(&pp->pr_lock);
			panic("pool_get: %s: page empty", pp->pr_wchan);
		}
#endif
		v = pr_item_notouch_get(pp, ph);
	} else {
		v = pi = LIST_FIRST(&ph->ph_itemlist);
		if (__predict_false(v == NULL)) {
			mutex_exit(&pp->pr_lock);
			panic("pool_get: %s: page empty", pp->pr_wchan);
		}
#ifdef DIAGNOSTIC
		if (__predict_false(pp->pr_nitems == 0)) {
			mutex_exit(&pp->pr_lock);
			printf("pool_get: %s: items on itemlist, nitems %u\n",
			    pp->pr_wchan, pp->pr_nitems);
			panic("pool_get: nitems inconsistent");
		}
#endif

#ifdef DIAGNOSTIC
		if (__predict_false(pi->pi_magic != PI_MAGIC)) {
			panic("pool_get(%s): free list modified: "
			    "magic=%x; page %p; item addr %p\n",
			    pp->pr_wchan, pi->pi_magic, ph->ph_page, pi);
		}
#endif

		/*
		 * Remove from item list.
		 */
		LIST_REMOVE(pi, pi_list);
	}
	pp->pr_nitems--;
	pp->pr_nout++;
	if (ph->ph_nmissing == 0) {
#ifdef DIAGNOSTIC
		if (__predict_false(pp->pr_nidle == 0))
			panic("pool_get: nidle inconsistent");
#endif
		pp->pr_nidle--;

		/*
		 * This page was previously empty.  Move it to the list of
		 * partially-full pages.  This page is already curpage.
		 */
		LIST_REMOVE(ph, ph_pagelist);
		LIST_INSERT_HEAD(&pp->pr_partpages, ph, ph_pagelist);
	}
	ph->ph_nmissing++;
	if (ph->ph_nmissing == pp->pr_itemsperpage) {
#ifdef DIAGNOSTIC
		if (__predict_false((pp->pr_roflags & PR_NOTOUCH) == 0 &&
		    !LIST_EMPTY(&ph->ph_itemlist))) {
			mutex_exit(&pp->pr_lock);
			panic("pool_get: %s: nmissing inconsistent",
			    pp->pr_wchan);
		}
#endif
		/*
		 * This page is now full.  Move it to the full list
		 * and select a new current page.
		 */
		LIST_REMOVE(ph, ph_pagelist);
		LIST_INSERT_HEAD(&pp->pr_fullpages, ph, ph_pagelist);
		pool_update_curpage(pp);
	}

	pp->pr_nget++;

	/*
	 * If we have a low water mark and we are now below that low
	 * water mark, add more items to the pool.
	 */
	if (POOL_NEEDS_CATCHUP(pp) && pool_catchup(pp) != 0) {
		/*
		 * XXX: Should we log a warning?  Should we set up a timeout
		 * to try again in a second or so?  The latter could break
		 * a caller's assumptions about interrupt protection, etc.
		 */
	}

	mutex_exit(&pp->pr_lock);
	KASSERT((((vaddr_t)v + pp->pr_itemoffset) & (pp->pr_align - 1)) == 0);
	FREECHECK_OUT(&pp->pr_freecheck, v);
	return (v);
}

/*
 * Internal version of pool_put().  Pool is already locked/entered.
 */
static void
pool_do_put(struct pool *pp, void *v, struct pool_pagelist *pq)
{
	struct pool_item *pi = v;
	struct pool_item_header *ph;

	KASSERT(mutex_owned(&pp->pr_lock));
	FREECHECK_IN(&pp->pr_freecheck, v);
	LOCKDEBUG_MEM_CHECK(v, pp->pr_size);

#ifdef DIAGNOSTIC
	if (__predict_false(pp->pr_nout == 0)) {
		printf("pool %s: putting with none out\n",
		    pp->pr_wchan);
		panic("pool_put");
	}
#endif

	if (__predict_false((ph = pr_find_pagehead(pp, v)) == NULL)) {
		panic("pool_put: %s: page header missing", pp->pr_wchan);
	}

	/*
	 * Return to item list.
	 */
	if (pp->pr_roflags & PR_NOTOUCH) {
		pr_item_notouch_put(pp, ph, v);
	} else {
#ifdef DIAGNOSTIC
		pi->pi_magic = PI_MAGIC;
#endif
#ifdef DEBUG
		{
			int i, *ip = v;

			for (i = 0; i < pp->pr_size / sizeof(int); i++) {
				*ip++ = PI_MAGIC;
			}
		}
#endif

		LIST_INSERT_HEAD(&ph->ph_itemlist, pi, pi_list);
	}
	KDASSERT(ph->ph_nmissing != 0);
	ph->ph_nmissing--;
	pp->pr_nput++;
	pp->pr_nitems++;
	pp->pr_nout--;

	/* Cancel "pool empty" condition if it exists */
	if (pp->pr_curpage == NULL)
		pp->pr_curpage = ph;

	if (pp->pr_flags & PR_WANTED) {
		pp->pr_flags &= ~PR_WANTED;
		cv_broadcast(&pp->pr_cv);
	}

	/*
	 * If this page is now empty, do one of two things:
	 *
	 *	(1) If we have more pages than the page high water mark,
	 *	    free the page back to the system.  ONLY CONSIDER
	 *	    FREEING BACK A PAGE IF WE HAVE MORE THAN OUR MINIMUM PAGE
	 *	    CLAIM.
	 *
	 *	(2) Otherwise, move the page to the empty page list.
	 *
	 * Either way, select a new current page (so we use a partially-full
	 * page if one is available).
	 */
	if (ph->ph_nmissing == 0) {
		pp->pr_nidle++;
		if (pp->pr_npages > pp->pr_minpages &&
		    pp->pr_npages > pp->pr_maxpages) {
			pr_rmpage(pp, ph, pq);
		} else {
			LIST_REMOVE(ph, ph_pagelist);
			LIST_INSERT_HEAD(&pp->pr_emptypages, ph, ph_pagelist);

			/*
			 * Update the timestamp on the page.  A page must
			 * be idle for some period of time before it can
			 * be reclaimed by the pagedaemon.  This minimizes
			 * ping-pong'ing for memory.
			 *
			 * note for 64-bit time_t: truncating to 32-bit is not
			 * a problem for our usage.
			 */
			ph->ph_time = time_uptime;
		}
		pool_update_curpage(pp);
	}

	/*
	 * If the page was previously completely full, move it to the
	 * partially-full list and make it the current page.  The next
	 * allocation will get the item from this page, instead of
	 * further fragmenting the pool.
	 */
	else if (ph->ph_nmissing == (pp->pr_itemsperpage - 1)) {
		LIST_REMOVE(ph, ph_pagelist);
		LIST_INSERT_HEAD(&pp->pr_partpages, ph, ph_pagelist);
		pp->pr_curpage = ph;
	}
}

void
pool_put(struct pool *pp, void *v)
{
	struct pool_pagelist pq;

	LIST_INIT(&pq);

	mutex_enter(&pp->pr_lock);
	pool_do_put(pp, v, &pq);
	mutex_exit(&pp->pr_lock);

	pr_pagelist_free(pp, &pq);
}

/*
 * pool_grow: grow a pool by a page.
 *
 * => called with pool locked.
 * => unlock and relock the pool.
 * => return with pool locked.
 */

static int
pool_grow(struct pool *pp, int flags)
{
	struct pool_item_header *ph = NULL;
	char *cp;

	mutex_exit(&pp->pr_lock);
	cp = pool_allocator_alloc(pp, flags);
	if (__predict_true(cp != NULL)) {
		ph = pool_alloc_item_header(pp, cp, flags);
	}
	if (__predict_false(cp == NULL || ph == NULL)) {
		if (cp != NULL) {
			pool_allocator_free(pp, cp);
		}
		mutex_enter(&pp->pr_lock);
		return ENOMEM;
	}

	mutex_enter(&pp->pr_lock);
	pool_prime_page(pp, cp, ph);
	pp->pr_npagealloc++;
	return 0;
}

/*
 * Add N items to the pool.
 */
int
pool_prime(struct pool *pp, int n)
{
	int newpages;
	int error = 0;

	mutex_enter(&pp->pr_lock);

	newpages = roundup(n, pp->pr_itemsperpage) / pp->pr_itemsperpage;

	while (newpages-- > 0) {
		error = pool_grow(pp, PR_NOWAIT);
		if (error) {
			break;
		}
		pp->pr_minpages++;
	}

	if (pp->pr_minpages >= pp->pr_maxpages)
		pp->pr_maxpages = pp->pr_minpages + 1;	/* XXX */

	mutex_exit(&pp->pr_lock);
	return error;
}

/*
 * Add a page worth of items to the pool.
 *
 * Note, we must be called with the pool descriptor LOCKED.
 */
static void
pool_prime_page(struct pool *pp, void *storage, struct pool_item_header *ph)
{
	struct pool_item *pi;
	void *cp = storage;
	const unsigned int align = pp->pr_align;
	const unsigned int ioff = pp->pr_itemoffset;
	int n;

	KASSERT(mutex_owned(&pp->pr_lock));

#ifdef DIAGNOSTIC
	if ((pp->pr_roflags & PR_NOALIGN) == 0 &&
	    ((uintptr_t)cp & (pp->pr_alloc->pa_pagesz - 1)) != 0)
		panic("pool_prime_page: %s: unaligned page", pp->pr_wchan);
#endif

	/*
	 * Insert page header.
	 */
	LIST_INSERT_HEAD(&pp->pr_emptypages, ph, ph_pagelist);
	LIST_INIT(&ph->ph_itemlist);
	ph->ph_page = storage;
	ph->ph_nmissing = 0;
	ph->ph_time = time_uptime;
	if ((pp->pr_roflags & PR_PHINPAGE) == 0)
		SPLAY_INSERT(phtree, &pp->pr_phtree, ph);

	pp->pr_nidle++;

	/*
	 * Color this page.
	 */
	ph->ph_off = pp->pr_curcolor;
	cp = (char *)cp + ph->ph_off;
	if ((pp->pr_curcolor += align) > pp->pr_maxcolor)
		pp->pr_curcolor = 0;

	/*
	 * Adjust storage to apply aligment to `pr_itemoffset' in each item.
	 */
	if (ioff != 0)
		cp = (char *)cp + align - ioff;

	KASSERT((((vaddr_t)cp + ioff) & (align - 1)) == 0);

	/*
	 * Insert remaining chunks on the bucket list.
	 */
	n = pp->pr_itemsperpage;
	pp->pr_nitems += n;

	if (pp->pr_roflags & PR_NOTOUCH) {
		pr_item_notouch_init(pp, ph);
	} else {
		while (n--) {
			pi = (struct pool_item *)cp;

			KASSERT(((((vaddr_t)pi) + ioff) & (align - 1)) == 0);

			/* Insert on page list */
			LIST_INSERT_HEAD(&ph->ph_itemlist, pi, pi_list);
#ifdef DIAGNOSTIC
			pi->pi_magic = PI_MAGIC;
#endif
			cp = (char *)cp + pp->pr_size;

			KASSERT((((vaddr_t)cp + ioff) & (align - 1)) == 0);
		}
	}

	/*
	 * If the pool was depleted, point at the new page.
	 */
	if (pp->pr_curpage == NULL)
		pp->pr_curpage = ph;

	if (++pp->pr_npages > pp->pr_hiwat)
		pp->pr_hiwat = pp->pr_npages;
}

/*
 * Used by pool_get() when nitems drops below the low water mark.  This
 * is used to catch up pr_nitems with the low water mark.
 *
 * Note 1, we never wait for memory here, we let the caller decide what to do.
 *
 * Note 2, we must be called with the pool already locked, and we return
 * with it locked.
 */
static int
pool_catchup(struct pool *pp)
{
	int error = 0;

	while (POOL_NEEDS_CATCHUP(pp)) {
		error = pool_grow(pp, PR_NOWAIT);
		if (error) {
			break;
		}
	}
	return error;
}

static void
pool_update_curpage(struct pool *pp)
{

	pp->pr_curpage = LIST_FIRST(&pp->pr_partpages);
	if (pp->pr_curpage == NULL) {
		pp->pr_curpage = LIST_FIRST(&pp->pr_emptypages);
	}
	KASSERT((pp->pr_curpage == NULL && pp->pr_nitems == 0) ||
	    (pp->pr_curpage != NULL && pp->pr_nitems > 0));
}

void
pool_setlowat(struct pool *pp, int n)
{

	mutex_enter(&pp->pr_lock);

	pp->pr_minitems = n;
	pp->pr_minpages = (n == 0)
		? 0
		: roundup(n, pp->pr_itemsperpage) / pp->pr_itemsperpage;

	/* Make sure we're caught up with the newly-set low water mark. */
	if (POOL_NEEDS_CATCHUP(pp) && pool_catchup(pp) != 0) {
		/*
		 * XXX: Should we log a warning?  Should we set up a timeout
		 * to try again in a second or so?  The latter could break
		 * a caller's assumptions about interrupt protection, etc.
		 */
	}

	mutex_exit(&pp->pr_lock);
}

void
pool_sethiwat(struct pool *pp, int n)
{

	mutex_enter(&pp->pr_lock);

	pp->pr_maxpages = (n == 0)
		? 0
		: roundup(n, pp->pr_itemsperpage) / pp->pr_itemsperpage;

	mutex_exit(&pp->pr_lock);
}

void
pool_sethardlimit(struct pool *pp, int n, const char *warnmess, int ratecap)
{

	mutex_enter(&pp->pr_lock);

	pp->pr_hardlimit = n;
	pp->pr_hardlimit_warning = warnmess;
	pp->pr_hardlimit_ratecap.tv_sec = ratecap;
	pp->pr_hardlimit_warning_last.tv_sec = 0;
	pp->pr_hardlimit_warning_last.tv_usec = 0;

	/*
	 * In-line version of pool_sethiwat(), because we don't want to
	 * release the lock.
	 */
	pp->pr_maxpages = (n == 0)
		? 0
		: roundup(n, pp->pr_itemsperpage) / pp->pr_itemsperpage;

	mutex_exit(&pp->pr_lock);
}

/*
 * Release all complete pages that have not been used recently.
 *
 * Might be called from interrupt context.
 */
int
pool_reclaim(struct pool *pp)
{
	struct pool_item_header *ph, *phnext;
	struct pool_pagelist pq;
	uint32_t curtime;
	bool klock;
	int rv;

	if (cpu_intr_p() || cpu_softintr_p()) {
		KASSERT(pp->pr_ipl != IPL_NONE);
	}

	if (pp->pr_drain_hook != NULL) {
		/*
		 * The drain hook must be called with the pool unlocked.
		 */
		(*pp->pr_drain_hook)(pp->pr_drain_hook_arg, PR_NOWAIT);
	}

	/*
	 * XXXSMP Because we do not want to cause non-MPSAFE code
	 * to block.
	 */
	if (pp->pr_ipl == IPL_SOFTNET || pp->pr_ipl == IPL_SOFTCLOCK ||
	    pp->pr_ipl == IPL_SOFTSERIAL) {
		KERNEL_LOCK(1, NULL);
		klock = true;
	} else
		klock = false;

	/* Reclaim items from the pool's cache (if any). */
	if (pp->pr_cache != NULL)
		pool_cache_invalidate(pp->pr_cache);

	if (mutex_tryenter(&pp->pr_lock) == 0) {
		if (klock) {
			KERNEL_UNLOCK_ONE(NULL);
		}
		return (0);
	}

	LIST_INIT(&pq);

	curtime = time_uptime;

	for (ph = LIST_FIRST(&pp->pr_emptypages); ph != NULL; ph = phnext) {
		phnext = LIST_NEXT(ph, ph_pagelist);

		/* Check our minimum page claim */
		if (pp->pr_npages <= pp->pr_minpages)
			break;

		KASSERT(ph->ph_nmissing == 0);
		if (curtime - ph->ph_time < pool_inactive_time)
			continue;

		/*
		 * If freeing this page would put us below
		 * the low water mark, stop now.
		 */
		if ((pp->pr_nitems - pp->pr_itemsperpage) <
		    pp->pr_minitems)
			break;

		pr_rmpage(pp, ph, &pq);
	}

	mutex_exit(&pp->pr_lock);

	if (LIST_EMPTY(&pq))
		rv = 0;
	else {
		pr_pagelist_free(pp, &pq);
		rv = 1;
	}

	if (klock) {
		KERNEL_UNLOCK_ONE(NULL);
	}

	return (rv);
}

/*
 * Drain pools, one at a time.  This is a two stage process;
 * drain_start kicks off a cross call to drain CPU-level caches
 * if the pool has an associated pool_cache.  drain_end waits
 * for those cross calls to finish, and then drains the cache
 * (if any) and pool.
 *
 * Note, must never be called from interrupt context.
 */
void
pool_drain_start(struct pool **ppp, uint64_t *wp)
{
	struct pool *pp;

	KASSERT(!TAILQ_EMPTY(&pool_head));

	pp = NULL;

	/* Find next pool to drain, and add a reference. */
	mutex_enter(&pool_head_lock);
	do {
		if (drainpp == NULL) {
			drainpp = TAILQ_FIRST(&pool_head);
		}
		if (drainpp != NULL) {
			pp = drainpp;
			drainpp = TAILQ_NEXT(pp, pr_poollist);
		}
		/*
		 * Skip completely idle pools.  We depend on at least
		 * one pool in the system being active.
		 */
	} while (pp == NULL || pp->pr_npages == 0);
	pp->pr_refcnt++;
	mutex_exit(&pool_head_lock);

	/* If there is a pool_cache, drain CPU level caches. */
	*ppp = pp;
	if (pp->pr_cache != NULL) {
		*wp = xc_broadcast(0, (xcfunc_t)pool_cache_transfer,
		    pp->pr_cache, NULL);
	}
}

bool
pool_drain_end(struct pool *pp, uint64_t where)
{
	bool reclaimed;

	if (pp == NULL)
		return false;

	KASSERT(pp->pr_refcnt > 0);

	/* Wait for remote draining to complete. */
	if (pp->pr_cache != NULL)
		xc_wait(where);

	/* Drain the cache (if any) and pool.. */
	reclaimed = pool_reclaim(pp);

	/* Finally, unlock the pool. */
	mutex_enter(&pool_head_lock);
	pp->pr_refcnt--;
	cv_broadcast(&pool_busy);
	mutex_exit(&pool_head_lock);

	return reclaimed;
}

/*
 * Diagnostic helpers.
 */

void
pool_printall(const char *modif, void (*pr)(const char *, ...))
{
	struct pool *pp;

	TAILQ_FOREACH(pp, &pool_head, pr_poollist) {
		pool_printit(pp, modif, pr);
	}
}

void
pool_printit(struct pool *pp, const char *modif, void (*pr)(const char *, ...))
{

	if (pp == NULL) {
		(*pr)("Must specify a pool to print.\n");
		return;
	}

	pool_print1(pp, modif, pr);
}

static void
pool_print_pagelist(struct pool *pp, struct pool_pagelist *pl,
    void (*pr)(const char *, ...))
{
	struct pool_item_header *ph;
#ifdef DIAGNOSTIC
	struct pool_item *pi;
#endif

	LIST_FOREACH(ph, pl, ph_pagelist) {
		(*pr)("\t\tpage %p, nmissing %d, time %" PRIu32 "\n",
		    ph->ph_page, ph->ph_nmissing, ph->ph_time);
#ifdef DIAGNOSTIC
		if (!(pp->pr_roflags & PR_NOTOUCH)) {
			LIST_FOREACH(pi, &ph->ph_itemlist, pi_list) {
				if (pi->pi_magic != PI_MAGIC) {
					(*pr)("\t\t\titem %p, magic 0x%x\n",
					    pi, pi->pi_magic);
				}
			}
		}
#endif
	}
}

static void
pool_print1(struct pool *pp, const char *modif, void (*pr)(const char *, ...))
{
	struct pool_item_header *ph;
	pool_cache_t pc;
	pcg_t *pcg;
	pool_cache_cpu_t *cc;
	uint64_t cpuhit, cpumiss;
	int i, print_log = 0, print_pagelist = 0, print_cache = 0;
	char c;

	while ((c = *modif++) != '\0') {
		if (c == 'l')
			print_log = 1;
		if (c == 'p')
			print_pagelist = 1;
		if (c == 'c')
			print_cache = 1;
	}

	if ((pc = pp->pr_cache) != NULL) {
		(*pr)("POOL CACHE");
	} else {
		(*pr)("POOL");
	}

	(*pr)(" %s: size %u, align %u, ioff %u, roflags 0x%08x\n",
	    pp->pr_wchan, pp->pr_size, pp->pr_align, pp->pr_itemoffset,
	    pp->pr_roflags);
	(*pr)("\talloc %p\n", pp->pr_alloc);
	(*pr)("\tminitems %u, minpages %u, maxpages %u, npages %u\n",
	    pp->pr_minitems, pp->pr_minpages, pp->pr_maxpages, pp->pr_npages);
	(*pr)("\titemsperpage %u, nitems %u, nout %u, hardlimit %u\n",
	    pp->pr_itemsperpage, pp->pr_nitems, pp->pr_nout, pp->pr_hardlimit);

	(*pr)("\tnget %lu, nfail %lu, nput %lu\n",
	    pp->pr_nget, pp->pr_nfail, pp->pr_nput);
	(*pr)("\tnpagealloc %lu, npagefree %lu, hiwat %u, nidle %lu\n",
	    pp->pr_npagealloc, pp->pr_npagefree, pp->pr_hiwat, pp->pr_nidle);

	if (print_pagelist == 0)
		goto skip_pagelist;

	if ((ph = LIST_FIRST(&pp->pr_emptypages)) != NULL)
		(*pr)("\n\tempty page list:\n");
	pool_print_pagelist(pp, &pp->pr_emptypages, pr);
	if ((ph = LIST_FIRST(&pp->pr_fullpages)) != NULL)
		(*pr)("\n\tfull page list:\n");
	pool_print_pagelist(pp, &pp->pr_fullpages, pr);
	if ((ph = LIST_FIRST(&pp->pr_partpages)) != NULL)
		(*pr)("\n\tpartial-page list:\n");
	pool_print_pagelist(pp, &pp->pr_partpages, pr);

	if (pp->pr_curpage == NULL)
		(*pr)("\tno current page\n");
	else
		(*pr)("\tcurpage %p\n", pp->pr_curpage->ph_page);

 skip_pagelist:
	if (print_log == 0)
		goto skip_log;

	(*pr)("\n");

 skip_log:

#define PR_GROUPLIST(pcg)						\
	(*pr)("\t\tgroup %p: avail %d\n", pcg, pcg->pcg_avail);		\
	for (i = 0; i < pcg->pcg_size; i++) {				\
		if (pcg->pcg_objects[i].pcgo_pa !=			\
		    POOL_PADDR_INVALID) {				\
			(*pr)("\t\t\t%p, 0x%llx\n",			\
			    pcg->pcg_objects[i].pcgo_va,		\
			    (unsigned long long)			\
			    pcg->pcg_objects[i].pcgo_pa);		\
		} else {						\
			(*pr)("\t\t\t%p\n",				\
			    pcg->pcg_objects[i].pcgo_va);		\
		}							\
	}

	if (pc != NULL) {
		cpuhit = 0;
		cpumiss = 0;
		for (i = 0; i < __arraycount(pc->pc_cpus); i++) {
			if ((cc = pc->pc_cpus[i]) == NULL)
				continue;
			cpuhit += cc->cc_hits;
			cpumiss += cc->cc_misses;
		}
		(*pr)("\tcpu layer hits %llu misses %llu\n", cpuhit, cpumiss);
		(*pr)("\tcache layer hits %llu misses %llu\n",
		    pc->pc_hits, pc->pc_misses);
		(*pr)("\tcache layer entry uncontended %llu contended %llu\n",
		    pc->pc_hits + pc->pc_misses - pc->pc_contended,
		    pc->pc_contended);
		(*pr)("\tcache layer empty groups %u full groups %u\n",
		    pc->pc_nempty, pc->pc_nfull);
		if (print_cache) {
			(*pr)("\tfull cache groups:\n");
			for (pcg = pc->pc_fullgroups; pcg != NULL;
			    pcg = pcg->pcg_next) {
				PR_GROUPLIST(pcg);
			}
			(*pr)("\tempty cache groups:\n");
			for (pcg = pc->pc_emptygroups; pcg != NULL;
			    pcg = pcg->pcg_next) {
				PR_GROUPLIST(pcg);
			}
		}
	}
#undef PR_GROUPLIST
}

static int
pool_chk_page(struct pool *pp, const char *label, struct pool_item_header *ph)
{
	struct pool_item *pi;
	void *page;
	int n;

	if ((pp->pr_roflags & PR_NOALIGN) == 0) {
		page = (void *)((uintptr_t)ph & pp->pr_alloc->pa_pagemask);
		if (page != ph->ph_page &&
		    (pp->pr_roflags & PR_PHINPAGE) != 0) {
			if (label != NULL)
				printf("%s: ", label);
			printf("pool(%p:%s): page inconsistency: page %p;"
			       " at page head addr %p (p %p)\n", pp,
				pp->pr_wchan, ph->ph_page,
				ph, page);
			return 1;
		}
	}

	if ((pp->pr_roflags & PR_NOTOUCH) != 0)
		return 0;

	for (pi = LIST_FIRST(&ph->ph_itemlist), n = 0;
	     pi != NULL;
	     pi = LIST_NEXT(pi,pi_list), n++) {

#ifdef DIAGNOSTIC
		if (pi->pi_magic != PI_MAGIC) {
			if (label != NULL)
				printf("%s: ", label);
			printf("pool(%s): free list modified: magic=%x;"
			       " page %p; item ordinal %d; addr %p\n",
				pp->pr_wchan, pi->pi_magic, ph->ph_page,
				n, pi);
			panic("pool");
		}
#endif
		if ((pp->pr_roflags & PR_NOALIGN) != 0) {
			continue;
		}
		page = (void *)((uintptr_t)pi & pp->pr_alloc->pa_pagemask);
		if (page == ph->ph_page)
			continue;

		if (label != NULL)
			printf("%s: ", label);
		printf("pool(%p:%s): page inconsistency: page %p;"
		       " item ordinal %d; addr %p (p %p)\n", pp,
			pp->pr_wchan, ph->ph_page,
			n, pi, page);
		return 1;
	}
	return 0;
}


int
pool_chk(struct pool *pp, const char *label)
{
	struct pool_item_header *ph;
	int r = 0;

	mutex_enter(&pp->pr_lock);
	LIST_FOREACH(ph, &pp->pr_emptypages, ph_pagelist) {
		r = pool_chk_page(pp, label, ph);
		if (r) {
			goto out;
		}
	}
	LIST_FOREACH(ph, &pp->pr_fullpages, ph_pagelist) {
		r = pool_chk_page(pp, label, ph);
		if (r) {
			goto out;
		}
	}
	LIST_FOREACH(ph, &pp->pr_partpages, ph_pagelist) {
		r = pool_chk_page(pp, label, ph);
		if (r) {
			goto out;
		}
	}

out:
	mutex_exit(&pp->pr_lock);
	return (r);
}

/*
 * pool_cache_init:
 *
 *	Initialize a pool cache.
 */
pool_cache_t
pool_cache_init(size_t size, u_int align, u_int align_offset, u_int flags,
    const char *wchan, struct pool_allocator *palloc, int ipl,
    int (*ctor)(void *, void *, int), void (*dtor)(void *, void *), void *arg)
{
	pool_cache_t pc;

	pc = pool_get(&cache_pool, PR_WAITOK);
	if (pc == NULL)
		return NULL;

	pool_cache_bootstrap(pc, size, align, align_offset, flags, wchan,
	   palloc, ipl, ctor, dtor, arg);

	return pc;
}

/*
 * pool_cache_bootstrap:
 *
 *	Kernel-private version of pool_cache_init().  The caller
 *	provides initial storage.
 */
void
pool_cache_bootstrap(pool_cache_t pc, size_t size, u_int align,
    u_int align_offset, u_int flags, const char *wchan,
    struct pool_allocator *palloc, int ipl,
    int (*ctor)(void *, void *, int), void (*dtor)(void *, void *),
    void *arg)
{
	CPU_INFO_ITERATOR cii;
	pool_cache_t pc1;
	struct cpu_info *ci;
	struct pool *pp;

	pp = &pc->pc_pool;
	if (palloc == NULL && ipl == IPL_NONE)
		palloc = &pool_allocator_nointr;
	pool_init(pp, size, align, align_offset, flags, wchan, palloc, ipl);
	mutex_init(&pc->pc_lock, MUTEX_DEFAULT, ipl);

	if (ctor == NULL) {
		ctor = (int (*)(void *, void *, int))nullop;
	}
	if (dtor == NULL) {
		dtor = (void (*)(void *, void *))nullop;
	}

	pc->pc_emptygroups = NULL;
	pc->pc_fullgroups = NULL;
	pc->pc_partgroups = NULL;
	pc->pc_ctor = ctor;
	pc->pc_dtor = dtor;
	pc->pc_arg  = arg;
	pc->pc_hits  = 0;
	pc->pc_misses = 0;
	pc->pc_nempty = 0;
	pc->pc_npart = 0;
	pc->pc_nfull = 0;
	pc->pc_contended = 0;
	pc->pc_refcnt = 0;
	pc->pc_freecheck = NULL;

	if ((flags & PR_LARGECACHE) != 0) {
		pc->pc_pcgsize = PCG_NOBJECTS_LARGE;
		pc->pc_pcgpool = &pcg_large_pool;
	} else {
		pc->pc_pcgsize = PCG_NOBJECTS_NORMAL;
		pc->pc_pcgpool = &pcg_normal_pool;
	}

	/* Allocate per-CPU caches. */
	memset(pc->pc_cpus, 0, sizeof(pc->pc_cpus));
	pc->pc_ncpu = 0;
	if (ncpu < 2) {
		/* XXX For sparc: boot CPU is not attached yet. */
		pool_cache_cpu_init1(curcpu(), pc);
	} else {
		for (CPU_INFO_FOREACH(cii, ci)) {
			pool_cache_cpu_init1(ci, pc);
		}
	}

	/* Add to list of all pools. */
	if (__predict_true(!cold))
		mutex_enter(&pool_head_lock);
	TAILQ_FOREACH(pc1, &pool_cache_head, pc_cachelist) {
		if (strcmp(pc1->pc_pool.pr_wchan, pc->pc_pool.pr_wchan) > 0)
			break;
	}
	if (pc1 == NULL)
		TAILQ_INSERT_TAIL(&pool_cache_head, pc, pc_cachelist);
	else
		TAILQ_INSERT_BEFORE(pc1, pc, pc_cachelist);
	if (__predict_true(!cold))
		mutex_exit(&pool_head_lock);

	membar_sync();
	pp->pr_cache = pc;
}

/*
 * pool_cache_destroy:
 *
 *	Destroy a pool cache.
 */
void
pool_cache_destroy(pool_cache_t pc)
{

	pool_cache_bootstrap_destroy(pc);
	pool_put(&cache_pool, pc);
}

/*
 * pool_cache_bootstrap_destroy:
 *
 *	Destroy a pool cache.
 */
void
pool_cache_bootstrap_destroy(pool_cache_t pc)
{
	struct pool *pp = &pc->pc_pool;
	u_int i;

	/* Remove it from the global list. */
	mutex_enter(&pool_head_lock);
	while (pc->pc_refcnt != 0)
		cv_wait(&pool_busy, &pool_head_lock);
	TAILQ_REMOVE(&pool_cache_head, pc, pc_cachelist);
	mutex_exit(&pool_head_lock);

	/* First, invalidate the entire cache. */
	pool_cache_invalidate(pc);

	/* Disassociate it from the pool. */
	mutex_enter(&pp->pr_lock);
	pp->pr_cache = NULL;
	mutex_exit(&pp->pr_lock);

	/* Destroy per-CPU data */
	for (i = 0; i < __arraycount(pc->pc_cpus); i++)
		pool_cache_invalidate_cpu(pc, i);

	/* Finally, destroy it. */
	mutex_destroy(&pc->pc_lock);
	pool_destroy(pp);
}

/*
 * pool_cache_cpu_init1:
 *
 *	Called for each pool_cache whenever a new CPU is attached.
 */
static void
pool_cache_cpu_init1(struct cpu_info *ci, pool_cache_t pc)
{
	pool_cache_cpu_t *cc;
	int index;

	index = ci->ci_index;

	KASSERT(index < __arraycount(pc->pc_cpus));

	if ((cc = pc->pc_cpus[index]) != NULL) {
		KASSERT(cc->cc_cpuindex == index);
		return;
	}

	/*
	 * The first CPU is 'free'.  This needs to be the case for
	 * bootstrap - we may not be able to allocate yet.
	 */
	if (pc->pc_ncpu == 0) {
		cc = &pc->pc_cpu0;
		pc->pc_ncpu = 1;
	} else {
		mutex_enter(&pc->pc_lock);
		pc->pc_ncpu++;
		mutex_exit(&pc->pc_lock);
		cc = pool_get(&cache_cpu_pool, PR_WAITOK);
	}

	cc->cc_ipl = pc->pc_pool.pr_ipl;
	cc->cc_iplcookie = makeiplcookie(cc->cc_ipl);
	cc->cc_cache = pc;
	cc->cc_cpuindex = index;
	cc->cc_hits = 0;
	cc->cc_misses = 0;
	cc->cc_current = __UNCONST(&pcg_dummy);
	cc->cc_previous = __UNCONST(&pcg_dummy);

	pc->pc_cpus[index] = cc;
}

/*
 * pool_cache_cpu_init:
 *
 *	Called whenever a new CPU is attached.
 */
void
pool_cache_cpu_init(struct cpu_info *ci)
{
	pool_cache_t pc;

	mutex_enter(&pool_head_lock);
	TAILQ_FOREACH(pc, &pool_cache_head, pc_cachelist) {
		pc->pc_refcnt++;
		mutex_exit(&pool_head_lock);

		pool_cache_cpu_init1(ci, pc);

		mutex_enter(&pool_head_lock);
		pc->pc_refcnt--;
		cv_broadcast(&pool_busy);
	}
	mutex_exit(&pool_head_lock);
}

/*
 * pool_cache_reclaim:
 *
 *	Reclaim memory from a pool cache.
 */
bool
pool_cache_reclaim(pool_cache_t pc)
{

	return pool_reclaim(&pc->pc_pool);
}

static void
pool_cache_destruct_object1(pool_cache_t pc, void *object)
{

	(*pc->pc_dtor)(pc->pc_arg, object);
	pool_put(&pc->pc_pool, object);
}

/*
 * pool_cache_destruct_object:
 *
 *	Force destruction of an object and its release back into
 *	the pool.
 */
void
pool_cache_destruct_object(pool_cache_t pc, void *object)
{

	FREECHECK_IN(&pc->pc_freecheck, object);

	pool_cache_destruct_object1(pc, object);
}

/*
 * pool_cache_invalidate_groups:
 *
 *	Invalidate a chain of groups and destruct all objects.
 */
static void
pool_cache_invalidate_groups(pool_cache_t pc, pcg_t *pcg)
{
	void *object;
	pcg_t *next;
	int i;

	for (; pcg != NULL; pcg = next) {
		next = pcg->pcg_next;

		for (i = 0; i < pcg->pcg_avail; i++) {
			object = pcg->pcg_objects[i].pcgo_va;
			pool_cache_destruct_object1(pc, object);
		}

		if (pcg->pcg_size == PCG_NOBJECTS_LARGE) {
			pool_put(&pcg_large_pool, pcg);
		} else {
			KASSERT(pcg->pcg_size == PCG_NOBJECTS_NORMAL);
			pool_put(&pcg_normal_pool, pcg);
		}
	}
}

/*
 * pool_cache_invalidate:
 *
 *	Invalidate a pool cache (destruct and release all of the
 *	cached objects).  Does not reclaim objects from the pool.
 *
 *	Note: For pool caches that provide constructed objects, there
 *	is an assumption that another level of synchronization is occurring
 *	between the input to the constructor and the cache invalidation.
 *
 *	Invalidation is a costly process and should not be called from
 *	interrupt context.
 */
void
pool_cache_invalidate(pool_cache_t pc)
{
	uint64_t where;
	pcg_t *full, *empty, *part;

	KASSERT(!cpu_intr_p() && !cpu_softintr_p());

	if (ncpu < 2 || !mp_online) {
		/*
		 * We might be called early enough in the boot process
		 * for the CPU data structures to not be fully initialized.
		 * In this case, transfer the content of the local CPU's
		 * cache back into global cache as only this CPU is currently
		 * running.
		 */
		pool_cache_transfer(pc);
	} else {
		/*
		 * Signal all CPUs that they must transfer their local
		 * cache back to the global pool then wait for the xcall to
		 * complete.
		 */
		where = xc_broadcast(0, (xcfunc_t)pool_cache_transfer,
		    pc, NULL);
		xc_wait(where);
	}

	/* Empty pool caches, then invalidate objects */
	mutex_enter(&pc->pc_lock);
	full = pc->pc_fullgroups;
	empty = pc->pc_emptygroups;
	part = pc->pc_partgroups;
	pc->pc_fullgroups = NULL;
	pc->pc_emptygroups = NULL;
	pc->pc_partgroups = NULL;
	pc->pc_nfull = 0;
	pc->pc_nempty = 0;
	pc->pc_npart = 0;
	mutex_exit(&pc->pc_lock);

	pool_cache_invalidate_groups(pc, full);
	pool_cache_invalidate_groups(pc, empty);
	pool_cache_invalidate_groups(pc, part);
}

/*
 * pool_cache_invalidate_cpu:
 *
 *	Invalidate all CPU-bound cached objects in pool cache, the CPU being
 *	identified by its associated index.
 *	It is caller's responsibility to ensure that no operation is
 *	taking place on this pool cache while doing this invalidation.
 *	WARNING: as no inter-CPU locking is enforced, trying to invalidate
 *	pool cached objects from a CPU different from the one currently running
 *	may result in an undefined behaviour.
 */
static void
pool_cache_invalidate_cpu(pool_cache_t pc, u_int index)
{
	pool_cache_cpu_t *cc;
	pcg_t *pcg;

	if ((cc = pc->pc_cpus[index]) == NULL)
		return;

	if ((pcg = cc->cc_current) != &pcg_dummy) {
		pcg->pcg_next = NULL;
		pool_cache_invalidate_groups(pc, pcg);
	}
	if ((pcg = cc->cc_previous) != &pcg_dummy) {
		pcg->pcg_next = NULL;
		pool_cache_invalidate_groups(pc, pcg);
	}
	if (cc != &pc->pc_cpu0)
		pool_put(&cache_cpu_pool, cc);

}

void
pool_cache_set_drain_hook(pool_cache_t pc, void (*fn)(void *, int), void *arg)
{

	pool_set_drain_hook(&pc->pc_pool, fn, arg);
}

void
pool_cache_setlowat(pool_cache_t pc, int n)
{

	pool_setlowat(&pc->pc_pool, n);
}

void
pool_cache_sethiwat(pool_cache_t pc, int n)
{

	pool_sethiwat(&pc->pc_pool, n);
}

void
pool_cache_sethardlimit(pool_cache_t pc, int n, const char *warnmess, int ratecap)
{

	pool_sethardlimit(&pc->pc_pool, n, warnmess, ratecap);
}

static bool __noinline
pool_cache_get_slow(pool_cache_cpu_t *cc, int s, void **objectp,
		    paddr_t *pap, int flags)
{
	pcg_t *pcg, *cur;
	uint64_t ncsw;
	pool_cache_t pc;
	void *object;

	KASSERT(cc->cc_current->pcg_avail == 0);
	KASSERT(cc->cc_previous->pcg_avail == 0);

	pc = cc->cc_cache;
	cc->cc_misses++;

	/*
	 * Nothing was available locally.  Try and grab a group
	 * from the cache.
	 */
	if (__predict_false(!mutex_tryenter(&pc->pc_lock))) {
		ncsw = curlwp->l_ncsw;
		mutex_enter(&pc->pc_lock);
		pc->pc_contended++;

		/*
		 * If we context switched while locking, then
		 * our view of the per-CPU data is invalid:
		 * retry.
		 */
		if (curlwp->l_ncsw != ncsw) {
			mutex_exit(&pc->pc_lock);
			return true;
		}
	}

	if (__predict_true((pcg = pc->pc_fullgroups) != NULL)) {
		/*
		 * If there's a full group, release our empty
		 * group back to the cache.  Install the full
		 * group as cc_current and return.
		 */
		if (__predict_true((cur = cc->cc_current) != &pcg_dummy)) {
			KASSERT(cur->pcg_avail == 0);
			cur->pcg_next = pc->pc_emptygroups;
			pc->pc_emptygroups = cur;
			pc->pc_nempty++;
		}
		KASSERT(pcg->pcg_avail == pcg->pcg_size);
		cc->cc_current = pcg;
		pc->pc_fullgroups = pcg->pcg_next;
		pc->pc_hits++;
		pc->pc_nfull--;
		mutex_exit(&pc->pc_lock);
		return true;
	}

	/*
	 * Nothing available locally or in cache.  Take the slow
	 * path: fetch a new object from the pool and construct
	 * it.
	 */
	pc->pc_misses++;
	mutex_exit(&pc->pc_lock);
	splx(s);

	object = pool_get(&pc->pc_pool, flags);
	*objectp = object;
	if (__predict_false(object == NULL))
		return false;

	if (__predict_false((*pc->pc_ctor)(pc->pc_arg, object, flags) != 0)) {
		pool_put(&pc->pc_pool, object);
		*objectp = NULL;
		return false;
	}

	KASSERT((((vaddr_t)object + pc->pc_pool.pr_itemoffset) &
	    (pc->pc_pool.pr_align - 1)) == 0);

	if (pap != NULL) {
#ifdef POOL_VTOPHYS
		*pap = POOL_VTOPHYS(object);
#else
		*pap = POOL_PADDR_INVALID;
#endif
	}

	FREECHECK_OUT(&pc->pc_freecheck, object);
	return false;
}

/*
 * pool_cache_get{,_paddr}:
 *
 *	Get an object from a pool cache (optionally returning
 *	the physical address of the object).
 */
void *
pool_cache_get_paddr(pool_cache_t pc, int flags, paddr_t *pap)
{
	pool_cache_cpu_t *cc;
	pcg_t *pcg;
	void *object;
	int s;

	KASSERTMSG((!cpu_intr_p() && !cpu_softintr_p()) ||
	    (pc->pc_pool.pr_ipl != IPL_NONE || cold || panicstr != NULL),
	    "pool '%s' is IPL_NONE, but called from interrupt context\n",
	    pc->pc_pool.pr_wchan);

	if (flags & PR_WAITOK) {
		ASSERT_SLEEPABLE();
	}

	/* Lock out interrupts and disable preemption. */
	s = splvm();
	while (/* CONSTCOND */ true) {
		/* Try and allocate an object from the current group. */
		cc = pc->pc_cpus[curcpu()->ci_index];
		KASSERT(cc->cc_cache == pc);
	 	pcg = cc->cc_current;
		if (__predict_true(pcg->pcg_avail > 0)) {
			object = pcg->pcg_objects[--pcg->pcg_avail].pcgo_va;
			if (__predict_false(pap != NULL))
				*pap = pcg->pcg_objects[pcg->pcg_avail].pcgo_pa;
#if defined(DIAGNOSTIC)
			pcg->pcg_objects[pcg->pcg_avail].pcgo_va = NULL;
			KASSERT(pcg->pcg_avail < pcg->pcg_size);
			KASSERT(object != NULL);
#endif
			cc->cc_hits++;
			splx(s);
			FREECHECK_OUT(&pc->pc_freecheck, object);
			return object;
		}

		/*
		 * That failed.  If the previous group isn't empty, swap
		 * it with the current group and allocate from there.
		 */
		pcg = cc->cc_previous;
		if (__predict_true(pcg->pcg_avail > 0)) {
			cc->cc_previous = cc->cc_current;
			cc->cc_current = pcg;
			continue;
		}

		/*
		 * Can't allocate from either group: try the slow path.
		 * If get_slow() allocated an object for us, or if
		 * no more objects are available, it will return false.
		 * Otherwise, we need to retry.
		 */
		if (!pool_cache_get_slow(cc, s, &object, pap, flags))
			break;
	}

	return object;
}

static bool __noinline
pool_cache_put_slow(pool_cache_cpu_t *cc, int s, void *object)
{
	pcg_t *pcg, *cur;
	uint64_t ncsw;
	pool_cache_t pc;

	KASSERT(cc->cc_current->pcg_avail == cc->cc_current->pcg_size);
	KASSERT(cc->cc_previous->pcg_avail == cc->cc_previous->pcg_size);

	pc = cc->cc_cache;
	pcg = NULL;
	cc->cc_misses++;

	/*
	 * If there are no empty groups in the cache then allocate one
	 * while still unlocked.
	 */
	if (__predict_false(pc->pc_emptygroups == NULL)) {
		if (__predict_true(!pool_cache_disable)) {
			pcg = pool_get(pc->pc_pcgpool, PR_NOWAIT);
		}
		if (__predict_true(pcg != NULL)) {
			pcg->pcg_avail = 0;
			pcg->pcg_size = pc->pc_pcgsize;
		}
	}

	/* Lock the cache. */
	if (__predict_false(!mutex_tryenter(&pc->pc_lock))) {
		ncsw = curlwp->l_ncsw;
		mutex_enter(&pc->pc_lock);
		pc->pc_contended++;

		/*
		 * If we context switched while locking, then our view of
		 * the per-CPU data is invalid: retry.
		 */
		if (__predict_false(curlwp->l_ncsw != ncsw)) {
			mutex_exit(&pc->pc_lock);
			if (pcg != NULL) {
				pool_put(pc->pc_pcgpool, pcg);
			}
			return true;
		}
	}

	/* If there are no empty groups in the cache then allocate one. */
	if (pcg == NULL && pc->pc_emptygroups != NULL) {
		pcg = pc->pc_emptygroups;
		pc->pc_emptygroups = pcg->pcg_next;
		pc->pc_nempty--;
	}

	/*
	 * If there's a empty group, release our full group back
	 * to the cache.  Install the empty group to the local CPU
	 * and return.
	 */
	if (pcg != NULL) {
		KASSERT(pcg->pcg_avail == 0);
		if (__predict_false(cc->cc_previous == &pcg_dummy)) {
			cc->cc_previous = pcg;
		} else {
			cur = cc->cc_current;
			if (__predict_true(cur != &pcg_dummy)) {
				KASSERT(cur->pcg_avail == cur->pcg_size);
				cur->pcg_next = pc->pc_fullgroups;
				pc->pc_fullgroups = cur;
				pc->pc_nfull++;
			}
			cc->cc_current = pcg;
		}
		pc->pc_hits++;
		mutex_exit(&pc->pc_lock);
		return true;
	}

	/*
	 * Nothing available locally or in cache, and we didn't
	 * allocate an empty group.  Take the slow path and destroy
	 * the object here and now.
	 */
	pc->pc_misses++;
	mutex_exit(&pc->pc_lock);
	splx(s);
	pool_cache_destruct_object(pc, object);

	return false;
} 

/*
 * pool_cache_put{,_paddr}:
 *
 *	Put an object back to the pool cache (optionally caching the
 *	physical address of the object).
 */
void
pool_cache_put_paddr(pool_cache_t pc, void *object, paddr_t pa)
{
	pool_cache_cpu_t *cc;
	pcg_t *pcg;
	int s;

	KASSERT(object != NULL);
	FREECHECK_IN(&pc->pc_freecheck, object);

	/* Lock out interrupts and disable preemption. */
	s = splvm();
	while (/* CONSTCOND */ true) {
		/* If the current group isn't full, release it there. */
		cc = pc->pc_cpus[curcpu()->ci_index];
		KASSERT(cc->cc_cache == pc);
	 	pcg = cc->cc_current;
		if (__predict_true(pcg->pcg_avail < pcg->pcg_size)) {
			pcg->pcg_objects[pcg->pcg_avail].pcgo_va = object;
			pcg->pcg_objects[pcg->pcg_avail].pcgo_pa = pa;
			pcg->pcg_avail++;
			cc->cc_hits++;
			splx(s);
			return;
		}

		/*
		 * That failed.  If the previous group isn't full, swap
		 * it with the current group and try again.
		 */
		pcg = cc->cc_previous;
		if (__predict_true(pcg->pcg_avail < pcg->pcg_size)) {
			cc->cc_previous = cc->cc_current;
			cc->cc_current = pcg;
			continue;
		}

		/*
		 * Can't free to either group: try the slow path. 
		 * If put_slow() releases the object for us, it
		 * will return false.  Otherwise we need to retry.
		 */
		if (!pool_cache_put_slow(cc, s, object))
			break;
	}
}

/*
 * pool_cache_transfer:
 *
 *	Transfer objects from the per-CPU cache to the global cache.
 *	Run within a cross-call thread.
 */
static void
pool_cache_transfer(pool_cache_t pc)
{
	pool_cache_cpu_t *cc;
	pcg_t *prev, *cur, **list;
	int s;

	s = splvm();
	mutex_enter(&pc->pc_lock);
	cc = pc->pc_cpus[curcpu()->ci_index];
	cur = cc->cc_current;
	cc->cc_current = __UNCONST(&pcg_dummy);
	prev = cc->cc_previous;
	cc->cc_previous = __UNCONST(&pcg_dummy);
	if (cur != &pcg_dummy) {
		if (cur->pcg_avail == cur->pcg_size) {
			list = &pc->pc_fullgroups;
			pc->pc_nfull++;
		} else if (cur->pcg_avail == 0) {
			list = &pc->pc_emptygroups;
			pc->pc_nempty++;
		} else {
			list = &pc->pc_partgroups;
			pc->pc_npart++;
		}
		cur->pcg_next = *list;
		*list = cur;
	}
	if (prev != &pcg_dummy) {
		if (prev->pcg_avail == prev->pcg_size) {
			list = &pc->pc_fullgroups;
			pc->pc_nfull++;
		} else if (prev->pcg_avail == 0) {
			list = &pc->pc_emptygroups;
			pc->pc_nempty++;
		} else {
			list = &pc->pc_partgroups;
			pc->pc_npart++;
		}
		prev->pcg_next = *list;
		*list = prev;
	}
	mutex_exit(&pc->pc_lock);
	splx(s);
}

/*
 * Pool backend allocators.
 *
 * Each pool has a backend allocator that handles allocation, deallocation,
 * and any additional draining that might be needed.
 *
 * We provide two standard allocators:
 *
 *	pool_allocator_kmem - the default when no allocator is specified
 *
 *	pool_allocator_nointr - used for pools that will not be accessed
 *	in interrupt context.
 */
void	*pool_page_alloc(struct pool *, int);
void	pool_page_free(struct pool *, void *);

#ifdef POOL_SUBPAGE
struct pool_allocator pool_allocator_kmem_fullpage = {
	.pa_alloc = pool_page_alloc,
	.pa_free = pool_page_free,
	.pa_pagesz = 0
};
#else
struct pool_allocator pool_allocator_kmem = {
	.pa_alloc = pool_page_alloc,
	.pa_free = pool_page_free,
	.pa_pagesz = 0
};
#endif

#ifdef POOL_SUBPAGE
struct pool_allocator pool_allocator_nointr_fullpage = {
	.pa_alloc = pool_page_alloc,
	.pa_free = pool_page_free,
	.pa_pagesz = 0
};
#else
struct pool_allocator pool_allocator_nointr = {
	.pa_alloc = pool_page_alloc,
	.pa_free = pool_page_free,
	.pa_pagesz = 0
};
#endif

#ifdef POOL_SUBPAGE
void	*pool_subpage_alloc(struct pool *, int);
void	pool_subpage_free(struct pool *, void *);

struct pool_allocator pool_allocator_kmem = {
	.pa_alloc = pool_subpage_alloc,
	.pa_free = pool_subpage_free,
	.pa_pagesz = POOL_SUBPAGE
};

struct pool_allocator pool_allocator_nointr = {
	.pa_alloc = pool_subpage_alloc,
	.pa_free = pool_subpage_free,
	.pa_pagesz = POOL_SUBPAGE
};
#endif /* POOL_SUBPAGE */

static void *
pool_allocator_alloc(struct pool *pp, int flags)
{
	struct pool_allocator *pa = pp->pr_alloc;
	void *res;

	res = (*pa->pa_alloc)(pp, flags);
	if (res == NULL && (flags & PR_WAITOK) == 0) {
		/*
		 * We only run the drain hook here if PR_NOWAIT.
		 * In other cases, the hook will be run in
		 * pool_reclaim().
		 */
		if (pp->pr_drain_hook != NULL) {
			(*pp->pr_drain_hook)(pp->pr_drain_hook_arg, flags);
			res = (*pa->pa_alloc)(pp, flags);
		}
	}
	return res;
}

static void
pool_allocator_free(struct pool *pp, void *v)
{
	struct pool_allocator *pa = pp->pr_alloc;

	(*pa->pa_free)(pp, v);
}

void *
pool_page_alloc(struct pool *pp, int flags)
{
	const vm_flag_t vflags = (flags & PR_WAITOK) ? VM_SLEEP: VM_NOSLEEP;
	vmem_addr_t va;
	int ret;

	ret = uvm_km_kmem_alloc(kmem_va_arena, pp->pr_alloc->pa_pagesz,
	    vflags | VM_INSTANTFIT, &va);

	return ret ? NULL : (void *)va;
}

void
pool_page_free(struct pool *pp, void *v)
{

	uvm_km_kmem_free(kmem_va_arena, (vaddr_t)v, pp->pr_alloc->pa_pagesz);
}

static void *
pool_page_alloc_meta(struct pool *pp, int flags)
{
	const vm_flag_t vflags = (flags & PR_WAITOK) ? VM_SLEEP: VM_NOSLEEP;
	vmem_addr_t va;
	int ret;

	ret = vmem_alloc(kmem_meta_arena, pp->pr_alloc->pa_pagesz,
	    vflags | VM_INSTANTFIT, &va);

	return ret ? NULL : (void *)va;
}

static void
pool_page_free_meta(struct pool *pp, void *v)
{

	vmem_free(kmem_meta_arena, (vmem_addr_t)v, pp->pr_alloc->pa_pagesz);
}

#ifdef POOL_SUBPAGE
/* Sub-page allocator, for machines with large hardware pages. */
void *
pool_subpage_alloc(struct pool *pp, int flags)
{
	return pool_get(&psppool, flags);
}

void
pool_subpage_free(struct pool *pp, void *v)
{
	pool_put(&psppool, v);
}

#endif /* POOL_SUBPAGE */

#if defined(DDB)
static bool
pool_in_page(struct pool *pp, struct pool_item_header *ph, uintptr_t addr)
{

	return (uintptr_t)ph->ph_page <= addr &&
	    addr < (uintptr_t)ph->ph_page + pp->pr_alloc->pa_pagesz;
}

static bool
pool_in_item(struct pool *pp, void *item, uintptr_t addr)
{

	return (uintptr_t)item <= addr && addr < (uintptr_t)item + pp->pr_size;
}

static bool
pool_in_cg(struct pool *pp, struct pool_cache_group *pcg, uintptr_t addr)
{
	int i;

	if (pcg == NULL) {
		return false;
	}
	for (i = 0; i < pcg->pcg_avail; i++) {
		if (pool_in_item(pp, pcg->pcg_objects[i].pcgo_va, addr)) {
			return true;
		}
	}
	return false;
}

static bool
pool_allocated(struct pool *pp, struct pool_item_header *ph, uintptr_t addr)
{

	if ((pp->pr_roflags & PR_NOTOUCH) != 0) {
		unsigned int idx = pr_item_notouch_index(pp, ph, (void *)addr);
		pool_item_bitmap_t *bitmap =
		    ph->ph_bitmap + (idx / BITMAP_SIZE);
		pool_item_bitmap_t mask = 1 << (idx & BITMAP_MASK);

		return (*bitmap & mask) == 0;
	} else {
		struct pool_item *pi;

		LIST_FOREACH(pi, &ph->ph_itemlist, pi_list) {
			if (pool_in_item(pp, pi, addr)) {
				return false;
			}
		}
		return true;
	}
}

void
pool_whatis(uintptr_t addr, void (*pr)(const char *, ...))
{
	struct pool *pp;

	TAILQ_FOREACH(pp, &pool_head, pr_poollist) {
		struct pool_item_header *ph;
		uintptr_t item;
		bool allocated = true;
		bool incache = false;
		bool incpucache = false;
		char cpucachestr[32];

		if ((pp->pr_roflags & PR_PHINPAGE) != 0) {
			LIST_FOREACH(ph, &pp->pr_fullpages, ph_pagelist) {
				if (pool_in_page(pp, ph, addr)) {
					goto found;
				}
			}
			LIST_FOREACH(ph, &pp->pr_partpages, ph_pagelist) {
				if (pool_in_page(pp, ph, addr)) {
					allocated =
					    pool_allocated(pp, ph, addr);
					goto found;
				}
			}
			LIST_FOREACH(ph, &pp->pr_emptypages, ph_pagelist) {
				if (pool_in_page(pp, ph, addr)) {
					allocated = false;
					goto found;
				}
			}
			continue;
		} else {
			ph = pr_find_pagehead_noalign(pp, (void *)addr);
			if (ph == NULL || !pool_in_page(pp, ph, addr)) {
				continue;
			}
			allocated = pool_allocated(pp, ph, addr);
		}
found:
		if (allocated && pp->pr_cache) {
			pool_cache_t pc = pp->pr_cache;
			struct pool_cache_group *pcg;
			int i;

			for (pcg = pc->pc_fullgroups; pcg != NULL;
			    pcg = pcg->pcg_next) {
				if (pool_in_cg(pp, pcg, addr)) {
					incache = true;
					goto print;
				}
			}
			for (i = 0; i < __arraycount(pc->pc_cpus); i++) {
				pool_cache_cpu_t *cc;

				if ((cc = pc->pc_cpus[i]) == NULL) {
					continue;
				}
				if (pool_in_cg(pp, cc->cc_current, addr) ||
				    pool_in_cg(pp, cc->cc_previous, addr)) {
					struct cpu_info *ci =
					    cpu_lookup(i);

					incpucache = true;
					snprintf(cpucachestr,
					    sizeof(cpucachestr),
					    "cached by CPU %u",
					    ci->ci_index);
					goto print;
				}
			}
		}
print:
		item = (uintptr_t)ph->ph_page + ph->ph_off;
		item = item + rounddown(addr - item, pp->pr_size);
		(*pr)("%p is %p+%zu in POOL '%s' (%s)\n",
		    (void *)addr, item, (size_t)(addr - item),
		    pp->pr_wchan,
		    incpucache ? cpucachestr :
		    incache ? "cached" : allocated ? "allocated" : "free");
	}
}
#endif /* defined(DDB) */