pool allocator from NetBSD (stays until uvm is ready)

2 files changed, 1246 insertions, 0 deletions

diff --git a/sys/kern/subr_pool.c b/sys/kern/subr_pool.c
new file mode 100644
index 00000000000..fc24ca24622
--- /dev/null
+++ b/sys/kern/subr_pool.c
@@ -0,0 +1,1092 @@
+/*	$OpenBSD: subr_pool.c,v 1.1 1999/02/26 03:13:30 art Exp $	*/
+/*	$NetBSD: subr_pool.c,v 1.17 1998/12/27 21:13:43 thorpej Exp $	*/
+
+/*-
+ * Copyright (c) 1997 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Paul Kranenburg.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the NetBSD
+ *	Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * 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/param.h>
+#include <sys/systm.h>
+#include <sys/proc.h>
+#include <sys/errno.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+#include <sys/lock.h>
+#include <sys/pool.h>
+
+#include <vm/vm.h>
+#include <vm/vm_kern.h>
+
+#if defined(UVM)
+#include <uvm/uvm.h>
+#endif  
+
+/*
+ * 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 a list headed by `pr_pagelist'
+ * in the pool structure and 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 */
+TAILQ_HEAD(,pool) pool_head = { NULL, &(pool_head).tqh_first };
+
+/* Private pool for page header structures */
+static struct pool phpool;
+
+/* # of seconds to retain page after last use */
+int pool_inactive_time = 10;
+
+/* Next candidate for drainage (see pool_drain()) */
+static struct pool	*drainpp = NULL;
+
+struct pool_item_header {
+	/* Page headers */
+	TAILQ_ENTRY(pool_item_header)
+				ph_pagelist;	/* pool page list */
+	TAILQ_HEAD(,pool_item)	ph_itemlist;	/* chunk list for this page */
+	LIST_ENTRY(pool_item_header)
+				ph_hashlist;	/* Off-page page headers */
+	int			ph_nmissing;	/* # of chunks in use */
+	caddr_t			ph_page;	/* this page's address */
+	struct timeval		ph_time;	/* last referenced */
+};
+
+struct pool_item {
+#ifdef DIAGNOSTIC
+	int pi_magic;
+#define PI_MAGIC 0xdeadbeef
+#endif
+	/* Other entries use only this list entry */
+	TAILQ_ENTRY(pool_item)	pi_list;
+};
+
+
+#define PR_HASH_INDEX(pp,addr) \
+	(((u_long)(addr) >> (pp)->pr_pageshift) & (PR_HASHTABSIZE - 1))
+
+
+
+static struct pool_item_header
+		*pr_find_pagehead __P((struct pool *, caddr_t));
+static void	pr_rmpage __P((struct pool *, struct pool_item_header *));
+static int	pool_prime_page __P((struct pool *, caddr_t));
+static void	*pool_page_alloc __P((unsigned long, int, int));
+static void	pool_page_free __P((void *, unsigned long, int));
+
+
+#ifdef POOL_DIAGNOSTIC
+/*
+ * Pool log entry. An array of these is allocated in pool_create().
+ */
+struct pool_log {
+	const char	*pl_file;
+	long		pl_line;
+	int		pl_action;
+#define PRLOG_GET	1
+#define PRLOG_PUT	2
+	void		*pl_addr;
+};
+
+/* Number of entries in pool log buffers */
+#ifndef POOL_LOGSIZE
+#define	POOL_LOGSIZE	10
+#endif
+
+int pool_logsize = POOL_LOGSIZE;
+
+static void	pr_log __P((struct pool *, void *, int, const char *, long));
+static void	pr_printlog __P((struct pool *));
+
+static __inline__ void
+pr_log(pp, v, action, file, line)
+	struct pool	*pp;
+	void		*v;
+	int		action;
+	const char	*file;
+	long		line;
+{
+	int n = pp->pr_curlogentry;
+	struct pool_log *pl;
+
+	if ((pp->pr_flags & PR_LOGGING) == 0)
+		return;
+
+	/*
+	 * Fill in the current entry. Wrap around and overwrite
+	 * the oldest entry if necessary.
+	 */
+	pl = &pp->pr_log[n];
+	pl->pl_file = file;
+	pl->pl_line = line;
+	pl->pl_action = action;
+	pl->pl_addr = v;
+	if (++n >= pp->pr_logsize)
+		n = 0;
+	pp->pr_curlogentry = n;
+}
+
+static void
+pr_printlog(pp)
+	struct pool *pp;
+{
+	int i = pp->pr_logsize;
+	int n = pp->pr_curlogentry;
+
+	if ((pp->pr_flags & PR_LOGGING) == 0)
+		return;
+
+	pool_print(pp, "printlog");
+
+	/*
+	 * Print all entries in this pool's log.
+	 */
+	while (i-- > 0) {
+		struct pool_log *pl = &pp->pr_log[n];
+		if (pl->pl_action != 0) {
+			printf("log entry %d:\n", i);
+			printf("\taction = %s, addr = %p\n",
+				pl->pl_action == PRLOG_GET ? "get" : "put",
+				pl->pl_addr);
+			printf("\tfile: %s at line %lu\n",
+				pl->pl_file, pl->pl_line);
+		}
+		if (++n >= pp->pr_logsize)
+			n = 0;
+	}
+}
+#else
+#define pr_log(pp, v, action, file, line)
+#define pr_printlog(pp)
+#endif
+
+
+/*
+ * Return the pool page header based on page address.
+ */
+static __inline__ struct pool_item_header *
+pr_find_pagehead(pp, page)
+	struct pool *pp;
+	caddr_t page;
+{
+	struct pool_item_header *ph;
+
+	if ((pp->pr_flags & PR_PHINPAGE) != 0)
+		return ((struct pool_item_header *)(page + pp->pr_phoffset));
+
+	for (ph = LIST_FIRST(&pp->pr_hashtab[PR_HASH_INDEX(pp, page)]);
+	     ph != NULL;
+	     ph = LIST_NEXT(ph, ph_hashlist)) {
+		if (ph->ph_page == page)
+			return (ph);
+	}
+	return (NULL);
+}
+
+/*
+ * Remove a page from the pool.
+ */
+static __inline__ void
+pr_rmpage(pp, ph)
+	struct pool *pp;
+	struct pool_item_header *ph;
+{
+
+	/*
+	 * 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");
+#endif
+		pp->pr_nidle--;
+	}
+
+	/*
+	 * Unlink a page from the pool and release it.
+	 */
+	TAILQ_REMOVE(&pp->pr_pagelist, ph, ph_pagelist);
+	(*pp->pr_free)(ph->ph_page, pp->pr_pagesz, pp->pr_mtype);
+	pp->pr_npages--;
+	pp->pr_npagefree++;
+
+	if ((pp->pr_flags & PR_PHINPAGE) == 0) {
+		LIST_REMOVE(ph, ph_hashlist);
+		pool_put(&phpool, ph);
+	}
+
+	if (pp->pr_curpage == ph) {
+		/*
+		 * Find a new non-empty page header, if any.
+		 * Start search from the page head, to increase the
+		 * chance for "high water" pages to be freed.
+		 */
+		for (ph = TAILQ_FIRST(&pp->pr_pagelist); ph != NULL;
+		     ph = TAILQ_NEXT(ph, ph_pagelist))
+			if (TAILQ_FIRST(&ph->ph_itemlist) != NULL)
+				break;
+
+		pp->pr_curpage = ph;
+	}
+}
+
+/*
+ * Allocate and initialize a pool.
+ */
+struct pool *
+pool_create(size, align, ioff, nitems, wchan, pagesz, alloc, release, mtype)
+	size_t	size;
+	u_int	align;
+	u_int	ioff;
+	int	nitems;
+	char	*wchan;
+	size_t	pagesz;
+	void	*(*alloc) __P((unsigned long, int, int));
+	void	(*release) __P((void *, unsigned long, int));
+	int	mtype;
+{
+	struct pool *pp;
+	int flags;
+
+	pp = (struct pool *)malloc(sizeof(*pp), M_POOL, M_NOWAIT);
+	if (pp == NULL)
+		return (NULL);
+
+	flags = PR_FREEHEADER;
+#ifdef POOL_DIAGNOSTIC
+	if (pool_logsize != 0)
+		flags |= PR_LOGGING;
+#endif
+
+	pool_init(pp, size, align, ioff, flags, wchan, pagesz,
+		  alloc, release, mtype);
+
+	if (nitems != 0) {
+		if (pool_prime(pp, nitems, NULL) != 0) {
+			pool_destroy(pp);
+			return (NULL);
+		}
+	}
+
+	return (pp);
+}
+
+/*
+ * Initialize the given pool resource structure.
+ *
+ * We export this routine to allow other kernel parts to declare
+ * static pools that must be initialized before malloc() is available.
+ */
+void
+pool_init(pp, size, align, ioff, flags, wchan, pagesz, alloc, release, mtype)
+	struct pool	*pp;
+	size_t		size;
+	u_int		align;
+	u_int		ioff;
+	int		flags;
+	char		*wchan;
+	size_t		pagesz;
+	void		*(*alloc) __P((unsigned long, int, int));
+	void		(*release) __P((void *, unsigned long, int));
+	int		mtype;
+{
+	int off, slack, i;
+
+	/*
+	 * Check arguments and construct default values.
+	 */
+	if (!powerof2(pagesz) || pagesz > PAGE_SIZE)
+		panic("pool_init: page size invalid (%lx)\n", (u_long)pagesz);
+
+	if (alloc == NULL && release == NULL) {
+		alloc = pool_page_alloc;
+		release = pool_page_free;
+		pagesz = PAGE_SIZE;	/* Rounds to PAGE_SIZE anyhow. */
+	} else if ((alloc != NULL && release != NULL) == 0) {
+		/* If you specifiy one, must specify both. */
+		panic("pool_init: must specify alloc and release together");
+	}
+			
+	if (pagesz == 0)
+		pagesz = PAGE_SIZE;
+
+	if (align == 0)
+		align = ALIGN(1);
+
+	if (size < sizeof(struct pool_item))
+		size = sizeof(struct pool_item);
+
+	/*
+	 * Initialize the pool structure.
+	 */
+	TAILQ_INSERT_TAIL(&pool_head, pp, pr_poollist);
+	TAILQ_INIT(&pp->pr_pagelist);
+	pp->pr_curpage = NULL;
+	pp->pr_npages = 0;
+	pp->pr_minitems = 0;
+	pp->pr_minpages = 0;
+	pp->pr_maxpages = UINT_MAX;
+	pp->pr_flags = flags;
+	pp->pr_size = ALIGN(size);
+	pp->pr_align = align;
+	pp->pr_wchan = wchan;
+	pp->pr_mtype = mtype;
+	pp->pr_alloc = alloc;
+	pp->pr_free = release;
+	pp->pr_pagesz = pagesz;
+	pp->pr_pagemask = ~(pagesz - 1);
+	pp->pr_pageshift = ffs(pagesz) - 1;
+
+	/*
+	 * Decide whether to put the page header off page to avoid
+	 * wasting too large a part of the page. 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 as the threshold (XXX: tune)
+	 */
+	if (pp->pr_size < pagesz/16) {
+		/* Use the end of the page for the page header */
+		pp->pr_flags |= PR_PHINPAGE;
+		pp->pr_phoffset = off =
+			pagesz - ALIGN(sizeof(struct pool_item_header));
+	} else {
+		/* The page header will be taken from our page header pool */
+		pp->pr_phoffset = 0;
+		off = pagesz;
+		for (i = 0; i < PR_HASHTABSIZE; i++) {
+			LIST_INIT(&pp->pr_hashtab[i]);
+		}
+	}
+
+	/*
+	 * 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.
+	 *
+	 * Silently enforce `0 <= ioff < align'.
+	 */
+	pp->pr_itemoffset = ioff = ioff % align;
+	pp->pr_itemsperpage = (off - ((align - ioff) % align)) / pp->pr_size;
+
+	/*
+	 * 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;
+
+#ifdef POOL_DIAGNOSTIC
+	if ((flags & PR_LOGGING) != 0) {
+		pp->pr_log = malloc(pool_logsize * sizeof(struct pool_log),
+				    M_TEMP, M_NOWAIT);
+		if (pp->pr_log == NULL)
+			pp->pr_flags &= ~PR_LOGGING;
+		pp->pr_curlogentry = 0;
+		pp->pr_logsize = pool_logsize;
+	}
+#endif
+
+	simple_lock_init(&pp->pr_lock);
+	lockinit(&pp->pr_resourcelock, PSWP, wchan, 0, 0);
+
+	/*
+	 * Initialize private page header pool if we haven't done so yet.
+	 */
+	if (phpool.pr_size == 0) {
+		pool_init(&phpool, sizeof(struct pool_item_header), 0, 0,
+			  0, "phpool", 0, 0, 0, 0);
+	}
+
+	return;
+}
+
+/*
+ * De-commision a pool resource.
+ */
+void
+pool_destroy(pp)
+	struct pool *pp;
+{
+	struct pool_item_header *ph;
+
+#ifdef DIAGNOSTIC
+	if (pp->pr_nget - pp->pr_nput != 0) {
+		pr_printlog(pp);
+		panic("pool_destroy: pool busy: still out: %lu\n",
+		      pp->pr_nget - pp->pr_nput);
+	}
+#endif
+
+	/* Remove all pages */
+	if ((pp->pr_flags & PR_STATIC) == 0)
+		while ((ph = pp->pr_pagelist.tqh_first) != NULL)
+			pr_rmpage(pp, ph);
+
+	/* Remove from global pool list */
+	TAILQ_REMOVE(&pool_head, pp, pr_poollist);
+	drainpp = NULL;
+
+#ifdef POOL_DIAGNOSTIC
+	if ((pp->pr_flags & PR_LOGGING) != 0)
+		free(pp->pr_log, M_TEMP);
+#endif
+
+	if (pp->pr_flags & PR_FREEHEADER)
+		free(pp, M_POOL);
+}
+
+
+/*
+ * Grab an item from the pool; must be called at appropriate spl level
+ */
+#ifdef POOL_DIAGNOSTIC
+void *
+_pool_get(pp, flags, file, line)
+	struct pool *pp;
+	int flags;
+	const char *file;
+	long line;
+#else
+void *
+pool_get(pp, flags)
+	struct pool *pp;
+	int flags;
+#endif
+{
+	void *v;
+	struct pool_item *pi;
+	struct pool_item_header *ph;
+
+#ifdef DIAGNOSTIC
+	if ((pp->pr_flags & PR_STATIC) && (flags & PR_MALLOCOK)) {
+		pr_printlog(pp);
+		panic("pool_get: static");
+	}
+#endif
+
+	simple_lock(&pp->pr_lock);
+	if (curproc == NULL && (flags & PR_WAITOK) != 0)
+		panic("pool_get: must have NOWAIT");
+
+	/*
+	 * 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.
+	 */
+	while ((ph = pp->pr_curpage) == NULL) {
+		void *v;
+		int lkflags = LK_EXCLUSIVE | LK_INTERLOCK |
+			      ((flags & PR_WAITOK) == 0 ? LK_NOWAIT : 0);
+
+		/* Get long-term lock on pool */
+		if (lockmgr(&pp->pr_resourcelock, lkflags, &pp->pr_lock,
+			    curproc /*XXX*/) != 0)
+			return (NULL);
+
+		/* Check if pool became non-empty while we slept */
+		if ((ph = pp->pr_curpage) != NULL)
+			goto again;
+
+		/* Call the page back-end allocator for more memory */
+		v = (*pp->pr_alloc)(pp->pr_pagesz, flags, pp->pr_mtype);
+		if (v == NULL) {
+			if (flags & PR_URGENT)
+				panic("pool_get: urgent");
+			if ((flags & PR_WAITOK) == 0) {
+				pp->pr_nfail++;
+				lockmgr(&pp->pr_resourcelock, LK_RELEASE, NULL,
+					curproc/*XXX*/);
+				return (NULL);
+			}
+
+			/*
+			 * Wait for items to be returned to this pool.
+			 * XXX: we actually want to wait just until
+			 * the page allocator has memory again. Depending
+			 * on this pool's usage, we might get stuck here
+			 * for a long time.
+			 */
+			pp->pr_flags |= PR_WANTED;
+			lockmgr(&pp->pr_resourcelock, LK_RELEASE, NULL,
+				curproc/*XXX*/);
+			tsleep((caddr_t)pp, PSWP, pp->pr_wchan, 0);
+			simple_lock(&pp->pr_lock);
+			continue;
+		}
+
+		/* We have more memory; add it to the pool */
+		pp->pr_npagealloc++;
+		pool_prime_page(pp, v);
+
+again:
+		/* Re-acquire pool interlock */
+		simple_lock(&pp->pr_lock);
+		lockmgr(&pp->pr_resourcelock, LK_RELEASE, NULL, curproc/*XXX*/);
+	}
+
+	if ((v = pi = TAILQ_FIRST(&ph->ph_itemlist)) == NULL)
+		panic("pool_get: %s: page empty", pp->pr_wchan);
+
+	pr_log(pp, v, PRLOG_GET, file, line);
+
+#ifdef DIAGNOSTIC
+	if (pi->pi_magic != PI_MAGIC) {
+		pr_printlog(pp);
+		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.
+	 */
+	TAILQ_REMOVE(&ph->ph_itemlist, pi, pi_list);
+	if (ph->ph_nmissing == 0) {
+#ifdef DIAGNOSTIC
+		if (pp->pr_nidle == 0)
+			panic("pool_get: nidle inconsistent");
+#endif
+		pp->pr_nidle--;
+	}
+	ph->ph_nmissing++;
+	if (TAILQ_FIRST(&ph->ph_itemlist) == NULL) {
+		/*
+		 * Find a new non-empty page header, if any.
+		 * Start search from the page head, to increase
+		 * the chance for "high water" pages to be freed.
+		 *
+		 * First, move the now empty page to the head of
+		 * the page list.
+		 */
+		TAILQ_REMOVE(&pp->pr_pagelist, ph, ph_pagelist);
+		TAILQ_INSERT_HEAD(&pp->pr_pagelist, ph, ph_pagelist);
+		while ((ph = TAILQ_NEXT(ph, ph_pagelist)) != NULL)
+			if (TAILQ_FIRST(&ph->ph_itemlist) != NULL)
+				break;
+
+		pp->pr_curpage = ph;
+	}
+
+	pp->pr_nget++;
+	simple_unlock(&pp->pr_lock);
+	return (v);
+}
+
+/*
+ * Return resource to the pool; must be called at appropriate spl level
+ */
+#ifdef POOL_DIAGNOSTIC
+void
+_pool_put(pp, v, file, line)
+	struct pool *pp;
+	void *v;
+	const char *file;
+	long line;
+#else
+void
+pool_put(pp, v)
+	struct pool *pp;
+	void *v;
+#endif
+{
+	struct pool_item *pi = v;
+	struct pool_item_header *ph;
+	caddr_t page;
+
+	page = (caddr_t)((u_long)v & pp->pr_pagemask);
+
+	simple_lock(&pp->pr_lock);
+
+	pr_log(pp, v, PRLOG_PUT, file, line);
+
+	if ((ph = pr_find_pagehead(pp, page)) == NULL) {
+		pr_printlog(pp);
+		panic("pool_put: %s: page header missing", pp->pr_wchan);
+	}
+
+	/*
+	 * Return to item list.
+	 */
+#ifdef DIAGNOSTIC
+	pi->pi_magic = PI_MAGIC;
+#endif
+	TAILQ_INSERT_HEAD(&ph->ph_itemlist, pi, pi_list);
+	ph->ph_nmissing--;
+	pp->pr_nput++;
+
+	/* 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;
+		if (ph->ph_nmissing == 0)
+			pp->pr_nidle++;
+		wakeup((caddr_t)pp);
+		simple_unlock(&pp->pr_lock);
+		return;
+	}
+
+	/*
+	 * If this page is now complete, move it to the end of the pagelist.
+	 * If this page has just become un-empty, move it the head.
+	 */
+	if (ph->ph_nmissing == 0) {
+		pp->pr_nidle++;
+		if (pp->pr_npages > pp->pr_maxpages) {
+#if 0
+			timeout(pool_drain, 0, pool_inactive_time*hz);
+#else
+			pr_rmpage(pp, ph);
+#endif
+		} else {
+			TAILQ_REMOVE(&pp->pr_pagelist, ph, ph_pagelist);
+			TAILQ_INSERT_TAIL(&pp->pr_pagelist, ph, ph_pagelist);
+			ph->ph_time = time;
+
+			/* XXX - update curpage */
+			for (ph = TAILQ_FIRST(&pp->pr_pagelist); ph != NULL;
+			     ph = TAILQ_NEXT(ph, ph_pagelist))
+				if (TAILQ_FIRST(&ph->ph_itemlist) != NULL)
+					break;
+
+			pp->pr_curpage = ph;
+		}
+	}
+
+	simple_unlock(&pp->pr_lock);
+}
+
+/*
+ * Add N items to the pool.
+ */
+int
+pool_prime(pp, n, storage)
+	struct pool *pp;
+	int n;
+	caddr_t storage;
+{
+	caddr_t cp;
+	int newnitems, newpages;
+
+#ifdef DIAGNOSTIC
+	if (storage && !(pp->pr_flags & PR_STATIC))
+		panic("pool_prime: static");
+	/* !storage && static caught below */
+#endif
+
+	(void)lockmgr(&pp->pr_resourcelock, LK_EXCLUSIVE, NULL, curproc/*XXX*/);
+	newnitems = pp->pr_minitems + n;
+	newpages =
+		roundup(pp->pr_itemsperpage,newnitems) / pp->pr_itemsperpage
+		- pp->pr_minpages;
+
+	while (newpages-- > 0) {
+
+		if (pp->pr_flags & PR_STATIC) {
+			cp = storage;
+			storage += pp->pr_pagesz;
+		} else {
+			cp = (*pp->pr_alloc)(pp->pr_pagesz, 0, pp->pr_mtype);
+		}
+
+		if (cp == NULL) {
+			(void)lockmgr(&pp->pr_resourcelock, LK_RELEASE, NULL,
+				      curproc/*XXX*/);
+			return (ENOMEM);
+		}
+
+		pool_prime_page(pp, cp);
+		pp->pr_minpages++;
+	}
+
+	pp->pr_minitems = newnitems;
+
+	if (pp->pr_minpages >= pp->pr_maxpages)
+		pp->pr_maxpages = pp->pr_minpages + 1;	/* XXX */
+
+	(void)lockmgr(&pp->pr_resourcelock, LK_RELEASE, NULL, curproc/*XXX*/);
+	return (0);
+}
+
+/*
+ * Add a page worth of items to the pool.
+ */
+int
+pool_prime_page(pp, storage)
+	struct pool *pp;
+	caddr_t storage;
+{
+	struct pool_item *pi;
+	struct pool_item_header *ph;
+	caddr_t cp = storage;
+	unsigned int align = pp->pr_align;
+	unsigned int ioff = pp->pr_itemoffset;
+	int n;
+
+	simple_lock(&pp->pr_lock);
+
+	if ((pp->pr_flags & PR_PHINPAGE) != 0) {
+		ph = (struct pool_item_header *)(cp + pp->pr_phoffset);
+	} else {
+		ph = pool_get(&phpool, PR_URGENT);
+		LIST_INSERT_HEAD(&pp->pr_hashtab[PR_HASH_INDEX(pp, cp)],
+				 ph, ph_hashlist);
+	}
+
+	/*
+	 * Insert page header.
+	 */
+	TAILQ_INSERT_HEAD(&pp->pr_pagelist, ph, ph_pagelist);
+	TAILQ_INIT(&ph->ph_itemlist);
+	ph->ph_page = storage;
+	ph->ph_nmissing = 0;
+	ph->ph_time.tv_sec = ph->ph_time.tv_usec = 0;
+
+	pp->pr_nidle++;
+
+	/*
+	 * Color this page.
+	 */
+	cp = (caddr_t)(cp + pp->pr_curcolor);
+	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 = (caddr_t)(cp + (align - ioff));
+
+	/*
+	 * Insert remaining chunks on the bucket list.
+	 */
+	n = pp->pr_itemsperpage;
+
+	while (n--) {
+		pi = (struct pool_item *)cp;
+
+		/* Insert on page list */
+		TAILQ_INSERT_TAIL(&ph->ph_itemlist, pi, pi_list);
+#ifdef DIAGNOSTIC
+		pi->pi_magic = PI_MAGIC;
+#endif
+		cp = (caddr_t)(cp + pp->pr_size);
+	}
+
+	/*
+	 * 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;
+
+	simple_unlock(&pp->pr_lock);
+	return (0);
+}
+
+void
+pool_setlowat(pp, n)
+	pool_handle_t	pp;
+	int n;
+{
+
+	(void)lockmgr(&pp->pr_resourcelock, LK_EXCLUSIVE, NULL, curproc/*XXX*/);
+	pp->pr_minitems = n;
+	pp->pr_minpages = (n == 0)
+		? 0
+		: roundup(pp->pr_itemsperpage,n) / pp->pr_itemsperpage;
+	(void)lockmgr(&pp->pr_resourcelock, LK_RELEASE, NULL, curproc/*XXX*/);
+}
+
+void
+pool_sethiwat(pp, n)
+	pool_handle_t	pp;
+	int n;
+{
+
+	(void)lockmgr(&pp->pr_resourcelock, LK_EXCLUSIVE, NULL, curproc/*XXX*/);
+	pp->pr_maxpages = (n == 0)
+		? 0
+		: roundup(pp->pr_itemsperpage,n) / pp->pr_itemsperpage;
+	(void)lockmgr(&pp->pr_resourcelock, LK_RELEASE, NULL, curproc/*XXX*/);
+}
+
+
+/*
+ * Default page allocator.
+ */
+static void *
+pool_page_alloc(sz, flags, mtype)
+	unsigned long sz;
+	int flags;
+	int mtype;
+{
+	boolean_t waitok = (flags & PR_WAITOK) ? TRUE : FALSE;
+
+#if defined(UVM)
+	return ((void *)uvm_km_alloc_poolpage(waitok));
+#else
+	return ((void *)kmem_alloc_poolpage(waitok));
+#endif
+}
+
+static void
+pool_page_free(v, sz, mtype)
+	void *v;
+	unsigned long sz;
+	int mtype;
+{
+
+#if defined(UVM)
+	uvm_km_free_poolpage((vaddr_t)v);
+#else
+	kmem_free_poolpage((vaddr_t)v);
+#endif  
+}
+
+/*
+ * Alternate pool page allocator for pools that know they will
+ * never be accessed in interrupt context.
+ */
+void *
+pool_page_alloc_nointr(sz, flags, mtype)
+	unsigned long sz;
+	int flags;
+	int mtype;
+{
+#if defined(UVM)
+	boolean_t waitok = (flags & PR_WAITOK) ? TRUE : FALSE;
+
+	/*
+	 * With UVM, we can use the kernel_map.
+	 */
+	return ((void *)uvm_km_alloc_poolpage1(kernel_map, uvm.kernel_object,
+	    waitok));
+#else
+	/*
+	 * Can't do anything so cool with Mach VM.
+	 */
+	return (pool_page_alloc(sz, flags, mtype));
+#endif
+}
+
+void
+pool_page_free_nointr(v, sz, mtype)
+	void *v;
+	unsigned long sz;
+	int mtype;
+{
+
+#if defined(UVM)
+	uvm_km_free_poolpage1(kernel_map, (vaddr_t)v);
+#else
+	pool_page_free(v, sz, mtype);
+#endif  
+}
+
+
+/*
+ * Release all complete pages that have not been used recently.
+ */
+void
+pool_reclaim (pp)
+	pool_handle_t pp;
+{
+	struct pool_item_header *ph, *phnext;
+	struct timeval curtime = time;
+
+	if (pp->pr_flags & PR_STATIC)
+		return;
+
+	if (simple_lock_try(&pp->pr_lock) == 0)
+		return;
+
+	for (ph = TAILQ_FIRST(&pp->pr_pagelist); ph != NULL; ph = phnext) {
+		phnext = TAILQ_NEXT(ph, ph_pagelist);
+
+		/* Check our minimum page claim */
+		if (pp->pr_npages <= pp->pr_minpages)
+			break;
+
+		if (ph->ph_nmissing == 0) {
+			struct timeval diff;
+			timersub(&curtime, &ph->ph_time, &diff);
+			if (diff.tv_sec < pool_inactive_time)
+				continue;
+			pr_rmpage(pp, ph);
+		}
+	}
+
+	simple_unlock(&pp->pr_lock);
+}
+
+
+/*
+ * Drain pools, one at a time.
+ */
+void
+pool_drain(arg)
+	void *arg;
+{
+	struct pool *pp;
+	int s = splimp();
+
+	/* XXX:lock pool head */
+	if (drainpp == NULL && (drainpp = TAILQ_FIRST(&pool_head)) == NULL) {
+		splx(s);
+		return;
+	}
+
+	pp = drainpp;
+	drainpp = TAILQ_NEXT(pp, pr_poollist);
+	/* XXX:unlock pool head */
+
+	pool_reclaim(pp);
+	splx(s);
+}
+
+
+#if defined(POOL_DIAGNOSTIC) || defined(DEBUG)
+/*
+ * Diagnostic helpers.
+ */
+void
+pool_print(pp, label)
+	struct pool *pp;
+	char *label;
+{
+
+	if (label != NULL)
+		printf("%s: ", label);
+
+	printf("pool %s: nalloc %lu nfree %lu npagealloc %lu npagefree %lu\n"
+	       "         npages %u minitems %u itemsperpage %u itemoffset %u\n"
+	       "         nidle %lu\n",
+		pp->pr_wchan,
+		pp->pr_nget,
+		pp->pr_nput,
+		pp->pr_npagealloc,
+		pp->pr_npagefree,
+		pp->pr_npages,
+		pp->pr_minitems,
+		pp->pr_itemsperpage,
+		pp->pr_itemoffset,
+		pp->pr_nidle);
+}
+
+int
+pool_chk(pp, label)
+	struct pool *pp;
+	char *label;
+{
+	struct pool_item_header *ph;
+	int r = 0;
+
+	simple_lock(&pp->pr_lock);
+
+	for (ph = TAILQ_FIRST(&pp->pr_pagelist); ph != NULL;
+	     ph = TAILQ_NEXT(ph, ph_pagelist)) {
+
+		struct pool_item *pi;
+		int n;
+		caddr_t page;
+
+		page = (caddr_t)((u_long)ph & pp->pr_pagemask);
+		if (page != ph->ph_page && (pp->pr_flags & 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);
+			r++;
+			goto out;
+		}
+
+		for (pi = TAILQ_FIRST(&ph->ph_itemlist), n = 0;
+		     pi != NULL;
+		     pi = TAILQ_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 (p %p)\n",
+					pp->pr_wchan, pi->pi_magic, ph->ph_page,
+					n, pi, page);
+				panic("pool");
+			}
+#endif
+			page = (caddr_t)((u_long)pi & pp->pr_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);
+			r++;
+			goto out;
+		}
+	}
+out:
+	simple_unlock(&pp->pr_lock);
+	return (r);
+}
+#endif /* POOL_DIAGNOSTIC || DEBUG */
diff --git a/sys/sys/pool.h b/sys/sys/pool.h
new file mode 100644
index 00000000000..cce9c1eb05b
--- /dev/null
+++ b/sys/sys/pool.h
@@ -0,0 +1,154 @@
+/*	$OpenBSD: pool.h,v 1.1 1999/02/26 03:13:29 art Exp $	*/
+/*	$NetBSD: pool.h,v 1.12 1998/12/27 21:13:43 thorpej Exp $	*/
+
+/*-
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Paul Kranenburg.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the NetBSD
+ *	Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * 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.
+ */
+
+#ifndef _SYS_POOL_H_
+#define _SYS_POOL_H_
+
+#include <sys/lock.h>
+#include <sys/queue.h>
+
+#define PR_HASHTABSIZE		8
+
+typedef struct pool {
+	TAILQ_ENTRY(pool)
+			pr_poollist;
+	TAILQ_HEAD(,pool_item_header)
+			pr_pagelist;	/* Allocated pages */
+	struct pool_item_header	*pr_curpage;
+	unsigned int	pr_size;	/* Size of item */
+	unsigned int	pr_align;	/* Requested alignment, must be 2^n */
+	unsigned int	pr_itemoffset;	/* Align this offset in item */
+	unsigned int	pr_minitems;	/* minimum # of items to keep */
+	unsigned int	pr_minpages;	/* same in page units */
+	unsigned int	pr_maxpages;	/* maximum # of pages to keep */
+	unsigned int	pr_npages;	/* # of pages allocated */
+	unsigned int	pr_pagesz;	/* page size, must be 2^n */
+	unsigned long	pr_pagemask;	/* abbrev. of above */
+	unsigned int	pr_pageshift;	/* shift corr. to above */
+	unsigned int	pr_itemsperpage;/* # items that fit in a page */
+	unsigned int	pr_slack;	/* unused space in a page */
+	void		*(*pr_alloc) __P((unsigned long, int, int));
+	void		(*pr_free) __P((void *, unsigned long, int));
+	int		pr_mtype;	/* memory allocator tag */
+	char		*pr_wchan;	/* tsleep(9) identifier */
+	unsigned int	pr_flags;
+#define PR_MALLOCOK	1
+#define	PR_NOWAIT	0		/* for symmetry */
+#define PR_WAITOK	2
+#define PR_WANTED	4
+#define PR_STATIC	8
+#define PR_FREEHEADER	16
+#define PR_URGENT	32
+#define PR_PHINPAGE	64
+#define PR_LOGGING	128
+
+	/*
+	 * `pr_lock' protects the pool's data structures when removing
+	 * items from or returning items to the pool.
+	 * `pr_resourcelock' is used to serialize access to the pool's
+	 * back-end page allocator. At the same time it also protects
+	 * the `pr_maxpages', `pr_minpages' and `pr_minitems' fields.
+	 */
+	struct simplelock	pr_lock;
+	struct lock		pr_resourcelock;
+
+	LIST_HEAD(,pool_item_header)		/* Off-page page headers */
+			pr_hashtab[PR_HASHTABSIZE];
+
+	int		pr_maxcolor;	/* Cache colouring */
+	int		pr_curcolor;
+	int		pr_phoffset;	/* Offset in page of page header */
+
+	/*
+	 * Instrumentation
+	 */
+	unsigned long	pr_nget;	/* # of successful requests */
+	unsigned long	pr_nfail;	/* # of unsuccessful requests */
+	unsigned long	pr_nput;	/* # of releases */
+	unsigned long	pr_npagealloc;	/* # of pages allocated */
+	unsigned long	pr_npagefree;	/* # of pages released */
+	unsigned int	pr_hiwat;	/* max # of pages in pool */
+	unsigned long	pr_nidle;	/* # of idle pages */
+
+#ifdef POOL_DIAGNOSTIC
+	struct pool_log	*pr_log;
+	int		pr_curlogentry;
+	int		pr_logsize;
+#endif
+} *pool_handle_t;
+
+pool_handle_t	pool_create __P((size_t, u_int, u_int,
+				 int, char *, size_t,
+				 void *(*)__P((unsigned long, int, int)),
+				 void  (*)__P((void *, unsigned long, int)),
+				 int));
+void		pool_init __P((struct pool *, size_t, u_int, u_int,
+				 int, char *, size_t,
+				 void *(*)__P((unsigned long, int, int)),
+				 void  (*)__P((void *, unsigned long, int)),
+				 int));
+void		pool_destroy __P((pool_handle_t));
+#ifdef POOL_DIAGNOSTIC
+void		*_pool_get __P((pool_handle_t, int, const char *, long));
+void		_pool_put __P((pool_handle_t, void *, const char *, long));
+#define		pool_get(h, f)	_pool_get((h), (f), __FILE__, __LINE__)
+#define		pool_put(h, v)	_pool_put((h), (v), __FILE__, __LINE__)
+#else
+void		*pool_get __P((pool_handle_t, int));
+void		pool_put __P((pool_handle_t, void *));
+#endif
+int		pool_prime __P((pool_handle_t, int, caddr_t));
+void		pool_setlowat __P((pool_handle_t, int));
+void		pool_sethiwat __P((pool_handle_t, int));
+void		pool_print __P((pool_handle_t, char *));
+void		pool_reclaim __P((pool_handle_t));
+void		pool_drain __P((void *));
+#if defined(POOL_DIAGNOSTIC) || defined(DEBUG)
+void		pool_print __P((struct pool *, char *));
+int		pool_chk __P((struct pool *, char *));
+#endif
+
+/*
+ * Alternate pool page allocator, provided for pools that know they
+ * will never be accessed in interrupt context.
+ */
+void		*pool_page_alloc_nointr __P((unsigned long, int, int));
+void		pool_page_free_nointr __P((void *, unsigned long, int));
+
+#endif /* _SYS_POOL_H_ */