Sync with reality. This is a work in progress.
This commit is contained in:
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@ -1,4 +1,4 @@
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.\" $NetBSD: pool_cache.9,v 1.5 2007/02/16 23:13:05 rmind Exp $
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.\" $NetBSD: pool_cache.9,v 1.6 2008/02/01 09:05:52 ad Exp $
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.\"
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.\" Copyright (c)2003 YAMAMOTO Takashi,
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.\" All rights reserved.
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@ -24,50 +24,43 @@
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" Copyright (c) 1997, 1999, 2000, 2007, 2008 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Paul Kranenburg; by Jason R. Thorpe of the Numerical Aerospace
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.\" Simulation Facility, NASA Ames Research Center, and by Andrew Doran.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" following copyright notice is from sys/kern/subr_pool.c.
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.\" they are here because i took some comments from it. yamt@NetBSD.org
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.\"
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.\"
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.\"/*-
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.\" * Copyright (c) 1997, 1999, 2000 The NetBSD Foundation, Inc.
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.\" * All rights reserved.
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.\" *
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.\" * This code is derived from software contributed to The NetBSD Foundation
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.\" * by Paul Kranenburg; by Jason R. Thorpe of the Numerical Aerospace
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.\" * Simulation Facility, NASA Ames Research Center.
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.\" *
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.\" * Redistribution and use in source and binary forms, with or without
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.\" * modification, are permitted provided that the following conditions
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.\" * are met:
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.\" * 1. Redistributions of source code must retain the above copyright
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.\" * notice, this list of conditions and the following disclaimer.
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.\" * 2. Redistributions in binary form must reproduce the above copyright
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.\" * notice, this list of conditions and the following disclaimer in the
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.\" * documentation and/or other materials provided with the distribution.
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.\" * 3. All advertising materials mentioning features or use of this software
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.\" * must display the following acknowledgement:
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.\" * This product includes software developed by the NetBSD
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.\" * Foundation, Inc. and its contributors.
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.\" * 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" * contributors may be used to endorse or promote products derived
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.\" * from this software without specific prior written permission.
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.\" *
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.\" * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" * POSSIBILITY OF SUCH DAMAGE.
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.\" */
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" ------------------------------------------------------------
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.Dd September 8, 2003
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.Dd Febuary 1, 2008
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.Dt POOL_CACHE 9
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.Os
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.\" ------------------------------------------------------------
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@ -80,79 +73,147 @@
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.Nm pool_cache_put_paddr ,
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.Nm pool_cache_put ,
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.Nm pool_cache_destruct_object ,
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.Nm pool_cache_invalidate
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.Nm pool_cache_invalidate ,
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.Nm pool_cache_sethiwat ,
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.Nm pool_cache_setlowat
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.Nd resource-pool cache manager
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.\" ------------------------------------------------------------
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.Sh SYNOPSIS
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.In sys/pool.h
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft void
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.Ft pool_cache_t
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.Fn pool_cache_init \
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"struct pool_cache *pc" "struct pool *pp" \
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"size_t size" "u_int align" "u_int align_offset" "int flags" \
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"const char *name" "struct pool_allocator *palloc" "int ipl" \
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"int (*ctor)(void *, void *, int)" "void (*dtor)(void *, void *)" "void *arg"
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft void
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.Fn pool_cache_destroy \
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"struct pool_cache *pc"
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"pool_cache_t pc"
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft void *
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.Fn pool_cache_get_paddr \
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"struct pool_cache *pc" "int flags" "paddr_t *pap"
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"pool_cache_t pc" "int flags" "paddr_t *pap"
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft void *
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.Fn pool_cache_get \
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"struct pool_cache *pc" "int flags"
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"pool_cache_t pc" "int flags"
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft void
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.Fn pool_cache_put_paddr \
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"struct pool_cache *pc" "void *object" "paddr_t pa"
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"pool_cache_t pc" "void *object" "paddr_t pa"
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft void
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.Fn pool_cache_put \
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"struct pool_cache *pc" "void *object"
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"pool_cache_t pc" "void *object"
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft void
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.Fn pool_cache_destruct_object \
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"struct pool_cache *pc" "void *object"
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"pool_cache_t pc" "void *object"
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.Ft void
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.Fn pool_cache_invalidate \
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"struct pool_cache *pc"
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"pool_cache_t pc"
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.Ft void
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.Fn pool_cache_sethiwat \
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"pool_cache_t pc" "int nitems"
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.Ft void
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.Fn pool_cache_setlowat \
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"pool_cache_t pc" "int nitems"
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.\" ------------------------------------------------------------
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.Sh DESCRIPTION
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The
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.Nm
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utility routines are provided to support caching of constructed objects,
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similar to the Solaris SLAB allocator.
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.Nm
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uses
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.Xr pool 9
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to allocate memory areas used for objects.
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If the pool must be protected from interrupts,
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.Nm
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routines expect to be called at the appropriate interrupt priority level.
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These utility routines provide management of pools of fixed-sized
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areas of memory.
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Resource pools set aside an amount of memory for exclusive use by the resource
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pool owner.
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This can be used by applications to guarantee the availability of a minimum
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amount of memory needed to continue operation independent of the memory
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resources currently available from the system-wide memory allocator.
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.Pp
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Global and per-CPU caches of constructed objects are maintained.
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The two levels of cache work together to allow for low overhead
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allocation and release of objects, and improved L1/L2/L3 hardware
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cache locality in multiprocessor systems.
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.\" ------------------------------------------------------------
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.Sh FUNCTIONS
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.Bl -tag -width compact
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.It Fn pool_cache_init "pc" "pp" "ctor" "dtor" "arg"
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Initialize a pool cache
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.Fa pc .
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The pool
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.Fa pp
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should be initialized by the caller in advance.
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.Fa ctor
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and
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.Fa dtor
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are object constructor and destructor.
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They can be
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.Pp
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Allocate and initialize a pool cache.
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The arguments are:
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.Pp
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.Bl -tag -width four
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.It Fa size
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.Pp
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Specifies the size of the memory items managed by the pool.
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.It Fa align
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.Pp
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Specifies the memory address alignment of the items returned by
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.Fn pool_cache_get .
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This argument must be a power of two.
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If zero,
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the alignment defaults to an architecture-specific natural alignment.
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.It Fa align_offset
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.Pp
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The offset within an item to which the
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.Fa align
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parameter applies.
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.It Fa flags
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.Pp
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Should be set to zero or
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.Dv PR_NOTOUCH .
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If
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.Dv PR_NOTOUCH
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is given, free items are never used to keep internal state so that
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the pool can be used for non memory backed objects.
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.It Fa name
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.Pp
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The name used to identify the object in diagnostic output.
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.It Fa palloc
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.Pp
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Should be typically be set to NULL, instructing
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.Fn pool_cache_init
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to select an appropriate back-end allocator.
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Alternate allocators can be used to partition space from arbitrary sources.
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Use of alternate allocators is not documented here as it is not a stable,
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endorsed part of the API.
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.It Fa ipl
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.Pp
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Specifies an interrupt priority level that will block all interrupt
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handlers that could potentially access the pool.
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The
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.Nm
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facility provides its own synchronization.
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The users of any given
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.Nm
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need not provide additional synchronization for access to it.
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.It Fa ctor
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.Pp
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Specifies a constructor used to initialize newly allocated objects.
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If no constructor is required, specify
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.Dv NULL .
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.It Fa dtor
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.Pp
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Specifies a destructor used to destroy cached objects prior to
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their release to backing store.
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If no destructor is required, specify
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.Dv NULL .
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.It Fa arg
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.Pp
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This value of this argument will be passed to both the constructor
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and destructor routines.
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.El
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.It Fn pool_cache_destroy "pc"
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Destroy a pool cache
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.Pp
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Destroy a pool cache.
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All other access to the cache must be stopped before this call
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can be made.
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.Fa pc .
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.It Fn pool_cache_get_paddr "pc" "flags" "pap"
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.Pp
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Get an object from a pool cache
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.Fa pc .
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If
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@ -171,6 +232,7 @@ and the object constructor specified when the pool cache is created by
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.Fn pool_cache_init .
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.It Fn pool_cache_get "pc" "flags"
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.Pp
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.Fn pool_cache_get
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is the same as
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.Fn pool_cache_get_paddr
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@ -181,6 +243,7 @@ argument.
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It's implemented as a macro.
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.It Fn pool_cache_put_paddr "pc" "object" "pa"
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.Pp
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Put an object
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.Fa object
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back to the pool cache
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@ -190,8 +253,15 @@ should be physical address of the object
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.Fa object
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or
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.Dv POOL_PADDR_INVALID .
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.Fa pp .
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If the number of available items in the backing pool exceeds the maximum
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pool size set by
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.Fn pool_cache_sethiwat
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and there are no outstanding requests for pool items,
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the excess items will be returned to the system.
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.It Fn pool_cache_put "pc" "object"
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.Pp
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.Fn pool_cache_put
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is the same as
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.Fn pool_cache_put_paddr
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@ -202,14 +272,48 @@ argument.
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It's implemented as a macro.
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.It Fn pool_cache_destruct_object "pc" "object"
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.Pp
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Force destruction of an object
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.Fa object
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and its release back into the pool.
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.It Fn pool_cache_invalidate "pc"
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.Pp
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Invalidate a pool cache
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.Fa pc .
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Destruct and release all of the cached objects.
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Destruct and release all objects in the global cache.
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Per-CPU caches will not be invalidated by this call, meaning that it
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is still possible to allocate "stale" items from the cache.
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If relevant, the user must check for this condition when allocating
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items.
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.It Fn pool_cache_sethiwat "pc" "nitems"
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.Pp
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A pool will attempt to increase its resource usage to keep up with the demand
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for its items.
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Conversely,
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it will return unused memory to the system should the number of accumulated
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unused items in the pool exceed a programmable limit.
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The limits for the minimum and maximum number of items which a pool should keep
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at hand are known as the high and low
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.Sy watermarks .
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.Pp
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The function
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.Fn pool_cache_sethiwat
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sets the backing pool's high water mark.
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As items are returned and the total number of pages in the pool is larger
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than the maximum set by this function,
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any completely unused pages are released immediately.
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If this function is not used to specify a maximum number of items,
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the pages will remain associated with the pool until the system runs low
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on memory,
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at which point the VM system will try to reclaim unused pages.
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.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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.It Fn pool_cache_setlowat "pc" "nitems"
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.Pp
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Set the minimum number of items to keep in the pool.
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The number pages in the pool will not decrease below the required value to
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accommodate the minimum number of items specified by this function.
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.El
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.\" ------------------------------------------------------------
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.Sh CODE REFERENCES
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@ -228,6 +332,7 @@ subsystem is implemented within the file
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.Pa sys/kern/subr_pool.c .
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.Sh SEE ALSO
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.Xr intro 9 ,
|
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.Xr malloc 9 ,
|
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.Xr kmem_alloc 9 ,
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.Xr kmem_free 9 ,
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.Xr memoryallocators 9 ,
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.Xr pool 9
|
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