ca108fe268
on top of a primary zone, sharing the same allocation "keg". When reporting statistics for zones, do not report the free items in the keg as part of the free items in the zone, or those free items will be reported more than once: for the primary zone, and then any secondary zones off the primary zone. Separately record and maintain a kegfree statistic, and export via memstat_get_kegfree(), which is available for use if needed. Since items free'd back to the keg are not fully initialized, and hence may not actually be available (since secondary zone ctor-time initialization can fail), this makes some amount of sense. This change corrects a bug made visible in the libmemstat(3) modifications to netstat: mbufs freed back to the keg from the packet zone would be counted twice, resulting in negative values being printed in the mbuf free count. Some further refinement of reporting relating to secondary zones may still be required. Reported by: ssouhlal MFC after: 3 days
276 lines
9.7 KiB
Groff
276 lines
9.7 KiB
Groff
.\" Copyright (c) 2005 Robert N. M. Watson
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.\" All rights reserved.
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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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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.\" $FreeBSD$
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.\"
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.Dd June 27, 2005
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.Os
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.Dt LIBMEMSTAT 3
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.Sh NAME
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.Nm libmemstat
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.Nd "library interface to retrieve kernel memory allocator statistics"
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.Sh LIBRARY
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.Lb libmemstat
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.Sh SYNOPSIS
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.In sys/types.h
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.In memstat.h
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.Ss Memory Type List Management Functions
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.Ft struct memory_type_list *
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.Fn memstat_mtl_alloc "void"
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.Ft struct memory_type *
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.Fn memstat_mtl_first "struct memory_type_list *list"
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.Ft struct memory_type *
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.Fn memstat_mtl_next "struct memory_type *mtp"
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.Ft struct memory_type *
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.Fn memstat_mtl_find "struct memory_type_list *list" "int allocator" "const char *name"
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.Ft void
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.Fn memstat_mtl_free "struct memory_type_list *list"
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.Ss Allocator Query Functions
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.Ft int
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.Fn memstat_sysctl_all "struct memory_type_list *list" "int flags"
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.Ft int
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.Fn memstat_sysctl_malloc "struct memory_type_list *list" "int flags"
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.Ft int
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.Fn memstat_sysctl_uma "struct memory_type_list *list" "int flags"
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.Ss Memory Type Accessor Methods
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.Ft const char *
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.Fn memstat_get_name "const struct memory_type *mtp"
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.Ft int
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.Fn memstat_get_allocator "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_countlimit "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_byteslimit "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_sizemask "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_size "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_memalloced "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_memfreed "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_numallocs "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_numfrees "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_bytes "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_count "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_free "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_failures "const struct memory_type *mtp"
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.Ft void *
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.Fn memstat_get_caller_pointer "const struct memory_type *mtp" "int index"
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.Ft void
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.Fn memstat_set_caller_pointer "struct memory_type *mtp" "int index" "void *value"
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.Ft uint64_t
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.Fn memstat_get_caller_uint64 "const struct memory_type *mtp" "int index"
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.Ft void
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.Fn memstat_set_caller_uint64 "struct memory_type *mtp" "int index" "uint64_t value"
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.Ft uint64_t
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.Fn memstat_get_zonefree "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_kegfree "const struct memory_type *mtp"
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.Ft uint64_t
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.Fn memstat_get_percpu_memalloced "const struct memory_type *mtp" "int cpu"
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.Ft uint64_t
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.Fn memstat_get_percpu_memfreed "const struct memory_type *mtp" "int cpu"
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.Ft uint64_t
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.Fn memstat_get_percpu_numallocs "const struct memory_type *mtp" "int cpu"
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.Ft uint64_t
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.Fn memstat_get_percpu_numfrees "const struct memory_type *mtp" "int cpu"
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.Ft uint64_t
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.Fn memstat_get_percpu_sizemask "const struct memory_type *mtp" "int cpu"
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.Ft void *
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.Fn memstat_get_percpu_caller_pointer "const struct memory_type *mtp" "int cpu" "int index"
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.Ft void
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.Fn memstat_set_percpu_caller_pointer "struct memory_type *mtp" "int cpu" "int index" "void *value"
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.Ft uint64_t
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.Fn memstat_get_percpu_caller_uint64 "const struct memory_type *mtp" "int cpu" "int index"
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.Ft void
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.Fn memstat_set_percpu_caller_uint64 "struct memory_type *mtp" "int cpu" "int index" "uint64_t value"
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.Ft uint64_t
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.Fn memstat_get_percpu_free "const struct memory_type *mtp" "int cpu"
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.Sh DESCRIPTION
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.Nm
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provides an interface to retrieve kernel memory allocator statistics, for
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the purposes of debugging and system monitoring, insulating applications
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from implementation details of the allocators, and allowing a tool to
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transparently support multiple allocators.
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.Nm
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supports both retrieving a single statistics snapshot, as well as
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incrementally updating statistics for long-term monitoring.
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.Pp
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.Nm
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describes each memory type using a
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.Vt struct memory_type ,
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an opaque memory type accessed by the application using accessor functions
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in the library.
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.Nm
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returns and updates chains of
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.Vt struct memory_type
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via a
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.Vt struct memory_type_list ,
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which will be allocated by calling
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.Fn memstat_mtl_alloc ,
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and freed on completion using
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.Fn memstat_mtl_free .
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Lists of memory types are populated via calls that query the kernel for
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statistics information; currently:
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.Fn memstat_sysctl_all ,
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.Fn memstat_sysctl_uma ,
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and
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.Fn memstat_sysctl_malloc .
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Repeated calls will incrementally update the list of memory types, permitting
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tracking over time without recreating all list state.
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Freeing the list will free all memory type data in the list, and so
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invalidates any outstanding pointers to entries in the list.
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.Vt struct memory_type
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entries in the list may be iterated over using
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.Fn memstat_mtl_first
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and
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.fn memstat_mtl_next ,
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which respectively return the first entry in a list, and the next entry in a
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list.
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.Fn memstat_mtl_find ,
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which will return a pointer to the first entry matching the passed
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parameters.
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.Pp
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A series of accessor methods is provided to access fields of the structure,
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including retrieving statistics and properties, as well as setting of caller
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owned fields.
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Direct application access to the data structure fields is not supported.
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.Ss Library memory_type Fields
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Each
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.Vt struct memory_type
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holds a description of the memory type, including its name and the allocator
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it is managed by, as well as current statistics on use.
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Some statistics are directly measured, others are derived from directly
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measured statistics.
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Certain high level statistics are present across all available allocators,
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such as the number of allocation and free operations; other measurements,
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such as the quantity of free items in per-CPU caches, or administrative
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limit on the number of allocations, is available only for specific
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allocators.
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.Ss Caller memory_type Fields
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.Vt struct memory_type
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includes fields to allow the application to store data, in the form of
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pointers and 64-bit integers, with memory types.
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For example, the application author might make use of one of the caller
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pointers to reference a more complex data structure tracking long-term
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behavior of the memory type, or a window system object that is used to
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render the state of the memory type.
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General and per-CPU storage is provided with each
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.Vt struct memory_type
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in the form of an array of pointers and integers.
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The array entries are accessed via the
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.Fa index
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argument to the get and set accessor methods.
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Possible values of
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.Fa index
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range between
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.Dv 0
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and
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.Dv MEMSTAT_MAXCALLER .
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.Pp
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Caller-owned fields are initialized to
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.Dv 0
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or
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.Dv NULL
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when a new
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.Vt struct memory_type
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is allocated and attached to a memory type list; these fields retain their
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values across queries that update library-owned fields.
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.Ss Allocator Types
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Currently,
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.Nm
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supports two kernel allocators:
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.Dv ALLOCATOR_UMA
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for
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.Xr uma 9 ,
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and
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.Dv ALLOCATOR_MALLOC
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for
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.Xr malloc 9 .
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These values may be passed to
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.Fn memstat_mtl_find ,
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and will be returned by
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.Fn memstat_get_allocator .
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Two additional constants in the allocator name space are defined:
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.Dv ALLOCATOR_UNKNOWN ,
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which will only be returned as a result of a library error, and
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.Dv ALLOCATOR_ANY ,
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which can be used to specify that returning types matching any allocator is
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permittible from
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.Fn memstat_mtl_find .
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.Sh EXAMPLES
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Create a memory type list, query the
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.Xr uma 9
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memory allocator for available statistics, and print out the number of
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allocations performed by the
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.Dv Mbuf
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zone.
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.Bd -literal -offset indent
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struct memory_type_list *mtlp;
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struct memory_type *mtp;
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uint64_t mbuf_count;
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mtlp = memstat_mtl_alloc();
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if (mtlp == NULL)
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err(-1, "memstat_mtl_alloc");
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if (memstat_sysctl_uma(mtlp, 0) < 0)
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err(-1, "memstat_sysctl_uma");
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mtp = memstat_mtl_find(mtlp, ALLOCATOR_UMA, "Mbuf");
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if (mtp == NULL)
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errx(-1, "memstat_mtl_find: Mbuf not found");
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mbuf_count = memstat_get_count(mtp);
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memstat_mtl_free(mtlp);
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printf("Mbufs: %llu\\n", (unsigned long long)mbuf_count);
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.Ed
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.Sh SEE ALSO
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.Xr malloc 9 ,
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.Xr uma 9
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.Sh HISTORY
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The
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.Nm memstat
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library appeared in
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.Fx 6.0 .
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.Sh AUTHORS
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The kernel memory allocator changes necessary to support a general purpose
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monitoring library, along with the library, were written by
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.An Robert Watson Aq rwatson@FreeBSD.org
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.Sh BUGS
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.Nm
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cannot yet extract statistics from kernel core dumps, although this should be
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straight forward to implement.
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.Pp
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Once a memory type is present on a memory type list, it will not be removed
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even if the kernel no longer presents information on the type via its
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monitoring interfaces.
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In order to flush removed memory types, it is necessary to free the entire
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list and allocate a new one.
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