dafde14e08
Remove medium size classes, because concurrent dirty page purging is no longer capable of purging inactive dirty pages inside active runs (due to recent arena/bin locking changes). Enhance tcache to support caching large objects, so that the same range of size classes is still cached, despite the removal of medium size class support.
1464 lines
56 KiB
Groff
1464 lines
56 KiB
Groff
.\" Copyright (c) 2006-2010 Jason Evans <jasone@canonware.com>.
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.\" All rights reserved.
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.\" Copyright (c) 2009 Facebook, Inc. All rights reserved.
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.\"
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.\" See COPYING for licensing terms provided by the above copyright holders.
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.\"
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.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the American National Standards Committee X3, on Information
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.\" Processing Systems.
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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. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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.\" @(#)malloc.3 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD: head/lib/libc/stdlib/malloc.3 182225 2008-08-27 02:00:53Z jasone $
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.\"
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.Dd March 17, 2010
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.Dt JEMALLOC 3
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.Os
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.Sh NAME
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.Nm @jemalloc_prefix@malloc ,
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.Nm @jemalloc_prefix@calloc ,
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.Nm @jemalloc_prefix@posix_memalign ,
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.Nm @jemalloc_prefix@realloc ,
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.Nm @jemalloc_prefix@free ,
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.Nm @jemalloc_prefix@malloc_usable_size ,
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.Nm @jemalloc_prefix@malloc_stats_print ,
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.Nm @jemalloc_prefix@mallctl ,
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.Nm @jemalloc_prefix@mallctlnametomib ,
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.Nm @jemalloc_prefix@mallctlbymib
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.Nd general purpose memory allocation functions
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.Sh LIBRARY
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.Sy libjemalloc@install_suffix@
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.Sh SYNOPSIS
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.In stdlib.h
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.In jemalloc/jemalloc@install_suffix@.h
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.Ft void *
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.Fn @jemalloc_prefix@malloc "size_t size"
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.Ft void *
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.Fn @jemalloc_prefix@calloc "size_t number" "size_t size"
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.Ft int
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.Fn @jemalloc_prefix@posix_memalign "void **ptr" "size_t alignment" "size_t size"
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.Ft void *
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.Fn @jemalloc_prefix@realloc "void *ptr" "size_t size"
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.Ft void
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.Fn @jemalloc_prefix@free "void *ptr"
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.Ft size_t
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.Fn @jemalloc_prefix@malloc_usable_size "const void *ptr"
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.Ft void
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.Fn @jemalloc_prefix@malloc_stats_print "void (*write_cb)(void *" "const char *)" "void *cbopaque" "const char *opts"
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.Ft int
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.Fn @jemalloc_prefix@mallctl "const char *name" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen"
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.Ft int
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.Fn @jemalloc_prefix@mallctlnametomib "const char *name" "int *mibp" "size_t *miblenp"
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.Ft int
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.Fn @jemalloc_prefix@mallctlbymib "const size_t *mib" "size_t miblen" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen"
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.Ft const char *
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.Va @jemalloc_prefix@malloc_options ;
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.Ft void
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.Fn \*(lp*@jemalloc_prefix@malloc_message\*(rp "void *cbopaque" "const char *s"
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.Sh DESCRIPTION
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|
The
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|
.Fn @jemalloc_prefix@malloc
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|
function allocates
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.Fa size
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bytes of uninitialized memory.
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The allocated space is suitably aligned
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@roff_tiny@(after possible pointer coercion)
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for storage of any type of object.
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.Pp
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|
The
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.Fn @jemalloc_prefix@calloc
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|
function allocates space for
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.Fa number
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objects,
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each
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.Fa size
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bytes in length.
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|
The result is identical to calling
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|
.Fn @jemalloc_prefix@malloc
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with an argument of
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.Dq "number * size" ,
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with the exception that the allocated memory is explicitly initialized
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to zero bytes.
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|
.Pp
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|
The
|
|
.Fn @jemalloc_prefix@posix_memalign
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|
function allocates
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|
.Fa size
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|
bytes of memory such that the allocation's base address is an even multiple of
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|
.Fa alignment ,
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|
and returns the allocation in the value pointed to by
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|
.Fa ptr .
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|
The requested
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|
.Fa alignment
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|
must be a power of 2 at least as large as
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|
.Fn sizeof "void *" .
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|
.Pp
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|
The
|
|
.Fn @jemalloc_prefix@realloc
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|
function changes the size of the previously allocated memory referenced by
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|
.Fa ptr
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|
to
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|
.Fa size
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|
bytes.
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|
The contents of the memory are unchanged up to the lesser of the new and
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|
old sizes.
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|
If the new size is larger,
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|
the contents of the newly allocated portion of the memory are undefined.
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|
Upon success, the memory referenced by
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|
.Fa ptr
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|
is freed and a pointer to the newly allocated memory is returned.
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|
Note that
|
|
.Fn @jemalloc_prefix@realloc
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|
may move the memory allocation, resulting in a different return value than
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|
.Fa ptr .
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|
If
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|
.Fa ptr
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is
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|
.Dv NULL ,
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the
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|
.Fn @jemalloc_prefix@realloc
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|
function behaves identically to
|
|
.Fn @jemalloc_prefix@malloc
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for the specified size.
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|
.Pp
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|
The
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|
.Fn @jemalloc_prefix@free
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|
function causes the allocated memory referenced by
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|
.Fa ptr
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|
to be made available for future allocations.
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|
If
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|
.Fa ptr
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|
is
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|
.Dv NULL ,
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no action occurs.
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|
.Pp
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|
The
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|
.Fn @jemalloc_prefix@malloc_usable_size
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|
function returns the usable size of the allocation pointed to by
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.Fa ptr .
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|
The return value may be larger than the size that was requested during
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allocation.
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|
The
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|
.Fn @jemalloc_prefix@malloc_usable_size
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|
function is not a mechanism for in-place
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|
.Fn @jemalloc_prefix@realloc ;
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|
rather it is provided solely as a tool for introspection purposes.
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|
Any discrepancy between the requested allocation size and the size reported by
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.Fn @jemalloc_prefix@malloc_usable_size
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|
should not be depended on, since such behavior is entirely
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implementation-dependent.
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.Pp
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|
The
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.Fn @jemalloc_prefix@malloc_stats_print
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|
function writes human-readable summary statistics via the
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.Fa write_cb
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|
callback function pointer and
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.Fa cbopaque
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|
data passed to
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.Fn write_cb ,
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|
or
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|
.Fn @jemalloc_prefix@malloc_message
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|
if
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|
.Fa write_cb
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|
is
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|
.Dv NULL .
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|
This function can be called repeatedly.
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|
General information that never changes
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|
during execution can be omitted by specifying
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|
.Dq g
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|
as a character within the
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|
.Fa opts
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|
string.
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|
Note that
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|
.Fn @jemalloc_prefix@malloc_message
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|
uses the
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|
.Fn @jemalloc_prefix@mallctl*
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|
functions internally, so inconsistent statistics can be reported if multiple
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threads use these functions simultaneously.
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|
@roff_stats@.Dq m
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|
@roff_stats@and
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|
@roff_stats@.Dq a
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|
@roff_stats@can be specified to omit merged arena and per arena statistics,
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|
@roff_stats@respectively.
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|
@roff_stats@.Dq b
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|
@roff_stats@and
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|
@roff_stats@.Dq l
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|
@roff_stats@can be specified to omit per size class statistics for bins and
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|
@roff_stats@large objects, respectively.
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|
Unrecognized characters are silently ignored.
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|
@roff_tcache@Note that thread caching may prevent some statistics from being
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|
@roff_tcache@completely up to date, since extra locking would be required to
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@roff_tcache@merge counters that track thread cache operations.
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.Pp
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|
The
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|
.Fn @jemalloc_prefix@mallctl
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|
function provides a general interface for introspecting the memory allocator,
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|
as well as setting modifiable parameters and triggering actions.
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|
The period-separated
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|
.Fa name
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|
argument specifies a location in a tree-structured namespace; see the
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|
.Sx "MALLCTL NAMESPACE"
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|
section for documentation on the tree contents.
|
|
To read a value, pass a pointer via
|
|
.Fa oldp
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|
to adequate space to contain the value, and a pointer to its length via
|
|
.Fa oldlenp ;
|
|
otherwise pass
|
|
.Dv NULL
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|
and
|
|
.Dv NULL .
|
|
Similarly, to write a value, pass a pointer to the value via
|
|
.Fa newp ,
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|
and its length via
|
|
.Fa newlen ;
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|
otherwise pass
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|
.Dv NULL
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|
and 0.
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|
.Pp
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|
The
|
|
.Fn @jemalloc_prefix@mallctlnametomib
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|
function provides a way to avoid repeated name lookups for applications that
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|
repeatedly query the same portion of the namespace, by translating a name to a
|
|
.Dq Management Information Base
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|
(MIB) that can be passed repeatedly to
|
|
.Fn @jemalloc_prefix@mallctlbymib .
|
|
Upon successful return from
|
|
.Fn @jemalloc_prefix@mallctlnametomib ,
|
|
.Fa mibp
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|
contains an array of
|
|
.Fa *miblenp
|
|
integers, where
|
|
.Fa *miblenp
|
|
is the lesser of the number of components in
|
|
.Fa name
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|
and the input value of
|
|
.Fa *miblenp .
|
|
Thus it is possible to pass a
|
|
.Fa *miblenp
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|
that is smaller than the number of period-separated name components, which
|
|
results in a partial MIB that can be used as the basis for constructing a
|
|
complete MIB.
|
|
For name components that are integers (e.g. the 2 in
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|
.Qq arenas.bin.2.size ) ,
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|
the corresponding MIB component will always be that integer.
|
|
Therefore, it is legitimate to construct code like the following:
|
|
.Pp
|
|
.Bd -literal -offset indent -compact
|
|
unsigned nbins, i;
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|
int mib[4];
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|
size_t len, miblen;
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|
|
|
len = sizeof(nbins);
|
|
@jemalloc_prefix@mallctl("arenas.nbins", &nbins, &len, NULL, 0);
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|
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|
miblen = 4;
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|
@jemalloc_prefix@mallnametomib("arenas.bin.0.size", mib, &miblen);
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|
for (i = 0; i < nbins; i++) {
|
|
size_t bin_size;
|
|
|
|
mib[2] = i;
|
|
len = sizeof(bin_size);
|
|
@jemalloc_prefix@mallctlbymib(mib, miblen, &bin_size, &len, NULL, 0);
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|
/* Do something with bin_size... */
|
|
}
|
|
.Ed
|
|
.Sh TUNING
|
|
Once, when the first call is made to one of these memory allocation
|
|
routines, various flags will be set or reset, which affects the
|
|
workings of this allocator implementation.
|
|
.Pp
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|
The
|
|
.Dq name
|
|
of the file referenced by the symbolic link named
|
|
.Pa /etc/jemalloc.conf ,
|
|
the value of the environment variable
|
|
.Ev JEMALLOC_OPTIONS ,
|
|
and the string pointed to by the global variable
|
|
.Va @jemalloc_prefix@malloc_options
|
|
will be interpreted, in that order, from left to right as flags.
|
|
.Pp
|
|
Each flag is a single letter, optionally prefixed by a non-negative base 10
|
|
integer repetition count.
|
|
For example,
|
|
.Dq 3N
|
|
is equivalent to
|
|
.Dq NNN .
|
|
Some flags control parameter magnitudes, where uppercase increases the
|
|
magnitude, and lowercase decreases the magnitude.
|
|
Other flags control boolean parameters, where uppercase indicates that a
|
|
behavior is set, or on, and lowercase means that a behavior is not set, or off.
|
|
.Bl -tag -width indent
|
|
.It A
|
|
All warnings (except for the warning about unknown
|
|
flags being set) become fatal.
|
|
The process will call
|
|
.Xr abort 3
|
|
in these cases.
|
|
@roff_prof@.It B
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|
@roff_prof@Double/halve the maximum backtrace depth when profiling memory
|
|
@roff_prof@allocation activity.
|
|
@roff_prof@The default is 4.
|
|
.It C
|
|
Double/halve the size of the maximum size class that is a multiple of the
|
|
cacheline size (64).
|
|
Above this size, subpage spacing (256 bytes) is used for size classes.
|
|
The default value is 512 bytes.
|
|
.It D
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|
Halve/double the per-arena minimum ratio of active to dirty pages.
|
|
Some dirty unused pages may be allowed to accumulate, within the limit set by
|
|
the ratio (or one chunk worth of dirty pages, whichever is greater), before
|
|
informing the kernel about some of those pages via
|
|
.Xr madvise 2 .
|
|
This provides the kernel with sufficient information to recycle dirty pages if
|
|
physical memory becomes scarce and the pages remain unused.
|
|
The default minimum ratio is 32:1;
|
|
.Ev JEMALLOC_OPTIONS=6D
|
|
will disable dirty page purging.
|
|
@roff_prof@.It F
|
|
@roff_prof@Profile memory allocation activity, and use an
|
|
@roff_prof@.Xr atexit 3
|
|
@roff_prof@function to dump final memory usage to a file named according to
|
|
@roff_prof@the pattern
|
|
@roff_prof@.Pa <prefix>.<pid>.<seq>.f.heap ,
|
|
@roff_prof@where
|
|
@roff_prof@.Pa <prefix>
|
|
@roff_prof@is controlled by the
|
|
@roff_prof@JEMALLOC_PROF_PREFIX
|
|
@roff_prof@environment variable.
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq B
|
|
@roff_prof@option for backtrace depth control.
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq S
|
|
@roff_prof@option for probabilistic sampling control.
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq I
|
|
@roff_prof@option for information on interval-triggered profile dumping, and the
|
|
@roff_prof@.Dq U
|
|
@roff_prof@option for information on high-water-triggered profile dumping.
|
|
@roff_prof@Profile output is compatible with the pprof Perl script, which is
|
|
@roff_prof@part of the google-perftools package
|
|
@roff_prof@(http://code.google.com/p/google-perftools/).
|
|
@roff_tcache@.It G
|
|
@roff_tcache@Double/halve the approximate interval (counted in terms of
|
|
@roff_tcache@thread-specific cache allocation/deallocation events) between full
|
|
@roff_tcache@thread-specific cache garbage collection sweeps.
|
|
@roff_tcache@Garbage collection is actually performed incrementally, one size
|
|
@roff_tcache@class at a time, in order to avoid large collection pauses.
|
|
@roff_tcache@The default sweep interval is 8192;
|
|
@roff_tcache@.Ev JEMALLOC_OPTIONS=14g
|
|
@roff_tcache@will disable garbage collection.
|
|
@roff_tcache@.It H
|
|
@roff_tcache@Enable/disable thread-specific caching.
|
|
@roff_tcache@When there are multiple threads, each thread uses a
|
|
@roff_tcache@thread-specific cache for objects up to a certain size.
|
|
@roff_tcache@Thread-specific caching allows many allocations to be satisfied
|
|
@roff_tcache@without performing any thread synchronization, at the cost of
|
|
@roff_tcache@increased memory use.
|
|
@roff_tcache@See the
|
|
@roff_tcache@.Dq G
|
|
@roff_tcache@and
|
|
@roff_tcache@.Dq M
|
|
@roff_tcache@options for related tuning information.
|
|
@roff_tcache@This option is enabled by default.
|
|
@roff_prof@.It I
|
|
@roff_prof@Double/halve the average interval between memory profile dumps, as
|
|
@roff_prof@measured in bytes of allocation activity.
|
|
@roff_prof@The actual interval between dumps may be sporadic because
|
|
@roff_prof@decentralized allocation counters are used to avoid synchronization
|
|
@roff_prof@bottlenecks.
|
|
@roff_prof@Profiles are dumped to files named according to the pattern
|
|
@roff_prof@.Pa <prefix>.<pid>.<seq>.i<iseq>.heap ,
|
|
@roff_prof@where
|
|
@roff_prof@.Pa <prefix>
|
|
@roff_prof@is controlled by the
|
|
@roff_prof@JEMALLOC_PROF_PREFIX
|
|
@roff_prof@environment variable.
|
|
@roff_prof@The default average interval is 1 GiB.
|
|
@roff_fill@.It J
|
|
@roff_fill@Each byte of new memory allocated by
|
|
@roff_fill@.Fn @jemalloc_prefix@malloc
|
|
@roff_fill@or
|
|
@roff_fill@.Fn @jemalloc_prefix@realloc
|
|
@roff_fill@will be initialized to 0xa5.
|
|
@roff_fill@All memory returned by
|
|
@roff_fill@.Fn @jemalloc_prefix@free
|
|
@roff_fill@or
|
|
@roff_fill@.Fn @jemalloc_prefix@realloc
|
|
@roff_fill@will be initialized to 0x5a.
|
|
@roff_fill@This is intended for debugging and will impact performance
|
|
@roff_fill@negatively.
|
|
.It K
|
|
Double/halve the virtual memory chunk size.
|
|
The default chunk size is 4 MiB.
|
|
@roff_prof@.It L
|
|
@roff_prof@Use an
|
|
@roff_prof@.Xr atexit 3
|
|
@roff_prof@function to report memory leaks.
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq B
|
|
@roff_prof@option for backtrace depth control.
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq F option for information on analyzing heap profile output.
|
|
@roff_prof@This option is disabled by default.
|
|
@roff_tcache@.It M
|
|
@roff_tcache@Double/halve the maximum size class to cache.
|
|
@roff_tcache@At a minimum, all small size classes are cached, and at a maximum
|
|
@roff_tcache@all large size classes are cached.
|
|
@roff_tcache@The default maximum is 32 KiB.
|
|
.It N
|
|
Double/halve the number of arenas.
|
|
The default number of arenas is four times the number of CPUs, or one if there
|
|
is a single CPU.
|
|
@roff_swap@.It O
|
|
@roff_swap@Over-commit memory as a side effect of using anonymous
|
|
@roff_swap@.Xr mmap 2
|
|
@roff_swap@@roff_dss@ and
|
|
@roff_swap@@roff_dss@.Xr sbrk 2
|
|
@roff_swap@for virtual memory allocation.
|
|
@roff_swap@In order for overcommit to be disabled, the
|
|
@roff_swap@.Dq swap.fds
|
|
@roff_swap@mallctl must have been successfully written to.
|
|
@roff_swap@This option is enabled by default.
|
|
.It P
|
|
The
|
|
.Fn malloc_stats_print
|
|
function is called at program exit via an
|
|
.Xr atexit 3
|
|
function.
|
|
@roff_stats@This has the potential to cause deadlock for a multi-threaded
|
|
@roff_stats@process that exits while one or more threads are executing in the
|
|
@roff_stats@memory allocation functions.
|
|
@roff_stats@Therefore, this option should only be used with care; it is
|
|
@roff_stats@primarily intended as a performance tuning aid during application
|
|
@roff_stats@development.
|
|
.It Q
|
|
Double/halve the size of the maximum size class that is a multiple of the
|
|
quantum (8 or 16 bytes, depending on architecture).
|
|
Above this size, cacheline spacing is used for size classes.
|
|
The default value is 128 bytes.
|
|
@roff_prof@.It S
|
|
@roff_prof@Double/halve the average interval between allocation samples, as
|
|
@roff_prof@measured in bytes of allocation activity.
|
|
@roff_prof@Increasing the sampling interval decreases profile fidelity, but
|
|
@roff_prof@also decreases the computational overhead.
|
|
@roff_prof@The default sample interval is one (i.e. all allocations are
|
|
@roff_prof@sampled).
|
|
@roff_prof@A sample interval greater than one implicitly disables leak
|
|
@roff_prof@reporting.
|
|
@roff_prof@.It U
|
|
@roff_prof@Trigger a memory profile dump every time the total virtual memory
|
|
@roff_prof@exceeds the previous maximum.
|
|
@roff_prof@Profiles are dumped to files named according to the pattern
|
|
@roff_prof@.Pa <prefix>.<pid>.<seq>.u<useq>.heap ,
|
|
@roff_prof@where
|
|
@roff_prof@.Pa <prefix>
|
|
@roff_prof@is controlled by the
|
|
@roff_prof@JEMALLOC_PROF_PREFIX
|
|
@roff_prof@environment variable.
|
|
@roff_prof@This option is disabled by default.
|
|
@roff_sysv@.It V
|
|
@roff_sysv@Attempting to allocate zero bytes will return a
|
|
@roff_sysv@.Dv NULL
|
|
@roff_sysv@pointer instead of a valid pointer.
|
|
@roff_sysv@(The default behavior is to make a minimal allocation and return a
|
|
@roff_sysv@pointer to it.)
|
|
@roff_sysv@This option is provided for System V compatibility.
|
|
@roff_sysv@@roff_xmalloc@This option is incompatible with the
|
|
@roff_sysv@@roff_xmalloc@.Dq X
|
|
@roff_sysv@@roff_xmalloc@option.
|
|
@roff_xmalloc@.It X
|
|
@roff_xmalloc@Rather than return failure for any allocation function, display a
|
|
@roff_xmalloc@diagnostic message on
|
|
@roff_xmalloc@.Dv STDERR_FILENO
|
|
@roff_xmalloc@and cause the program to drop core (using
|
|
@roff_xmalloc@.Xr abort 3 ) .
|
|
@roff_xmalloc@This option should be set at compile time by including the
|
|
@roff_xmalloc@following in the source code:
|
|
@roff_xmalloc@.Bd -literal -offset indent
|
|
@roff_xmalloc@@jemalloc_prefix@malloc_options = "X";
|
|
@roff_xmalloc@.Ed
|
|
@roff_fill@.It Z
|
|
@roff_fill@Each byte of new memory allocated by
|
|
@roff_fill@.Fn @jemalloc_prefix@malloc
|
|
@roff_fill@or
|
|
@roff_fill@.Fn @jemalloc_prefix@realloc
|
|
@roff_fill@will be initialized to 0.
|
|
@roff_fill@Note that this initialization only happens once for each byte, so
|
|
@roff_fill@.Fn @jemalloc_prefix@realloc
|
|
@roff_fill@calls do not zero memory that was previously allocated.
|
|
@roff_fill@This is intended for debugging and will impact performance
|
|
@roff_fill@negatively.
|
|
.El
|
|
.Pp
|
|
@roff_fill@The
|
|
@roff_fill@.Dq J
|
|
@roff_fill@and
|
|
@roff_fill@.Dq Z
|
|
@roff_fill@options are intended for testing and debugging.
|
|
@roff_fill@An application which changes its behavior when these options are used
|
|
@roff_fill@is flawed.
|
|
.Sh IMPLEMENTATION NOTES
|
|
@roff_dss@Traditionally, allocators have used
|
|
@roff_dss@.Xr sbrk 2
|
|
@roff_dss@to obtain memory, which is suboptimal for several reasons, including
|
|
@roff_dss@race conditions, increased fragmentation, and artificial limitations
|
|
@roff_dss@on maximum usable memory.
|
|
@roff_dss@This allocator uses both
|
|
@roff_dss@.Xr sbrk 2
|
|
@roff_dss@and
|
|
@roff_dss@.Xr mmap 2 ,
|
|
@roff_dss@in that order of preference.
|
|
.Pp
|
|
This allocator uses multiple arenas in order to reduce lock contention for
|
|
threaded programs on multi-processor systems.
|
|
This works well with regard to threading scalability, but incurs some costs.
|
|
There is a small fixed per-arena overhead, and additionally, arenas manage
|
|
memory completely independently of each other, which means a small fixed
|
|
increase in overall memory fragmentation.
|
|
These overheads are not generally an issue, given the number of arenas normally
|
|
used.
|
|
Note that using substantially more arenas than the default is not likely to
|
|
improve performance, mainly due to reduced cache performance.
|
|
However, it may make sense to reduce the number of arenas if an application
|
|
does not make much use of the allocation functions.
|
|
.Pp
|
|
@roff_tcache@In addition to multiple arenas, this allocator supports
|
|
@roff_tcache@thread-specific caching for small objects, in order to make it
|
|
@roff_tcache@possible to completely avoid synchronization for most small
|
|
@roff_tcache@allocation requests.
|
|
@roff_tcache@Such caching allows very fast allocation in the common case, but it
|
|
@roff_tcache@increases memory usage and fragmentation, since a bounded number of
|
|
@roff_tcache@objects can remain allocated in each thread cache.
|
|
@roff_tcache@.Pp
|
|
Memory is conceptually broken into equal-sized chunks, where the chunk size is
|
|
a power of two that is greater than the page size.
|
|
Chunks are always aligned to multiples of the chunk size.
|
|
This alignment makes it possible to find metadata for user objects very
|
|
quickly.
|
|
.Pp
|
|
User objects are broken into three categories according to size: small, large,
|
|
and huge.
|
|
Small objects are smaller than one page.
|
|
Large objects are smaller than the chunk size.
|
|
Huge objects are a multiple of the chunk size.
|
|
Small and large objects are managed by arenas; huge objects are managed
|
|
separately in a single data structure that is shared by all threads.
|
|
Huge objects are used by applications infrequently enough that this single
|
|
data structure is not a scalability issue.
|
|
.Pp
|
|
Each chunk that is managed by an arena tracks its contents as runs of
|
|
contiguous pages (unused, backing a set of small objects, or backing one large
|
|
object).
|
|
The combination of chunk alignment and chunk page maps makes it possible to
|
|
determine all metadata regarding small and large allocations in constant time.
|
|
.Pp
|
|
Small objects are managed in groups by page runs.
|
|
Each run maintains a bitmap that tracks which regions are in use.
|
|
@roff_tiny@Allocation requests that are no more than half the quantum (8 or 16,
|
|
@roff_tiny@depending on architecture) are rounded up to the nearest power of
|
|
@roff_tiny@two.
|
|
Allocation requests that are
|
|
@roff_tiny@more than half the quantum, but
|
|
no more than the minimum cacheline-multiple size class (see the
|
|
.Dq Q
|
|
option) are rounded up to the nearest multiple of the
|
|
@roff_tiny@quantum.
|
|
@roff_no_tiny@quantum (8 or 16, depending on architecture).
|
|
Allocation requests that are more than the minimum cacheline-multiple size
|
|
class, but no more than the minimum subpage-multiple size class (see the
|
|
.Dq C
|
|
option) are rounded up to the nearest multiple of the cacheline size (64).
|
|
Allocation requests that are more than the minimum subpage-multiple size class,
|
|
but no more than the maximum subpage-multiple size class are rounded up to the
|
|
nearest multiple of the subpage size (256).
|
|
Allocation requests that are more than the maximum subpage-multiple size class,
|
|
but small enough to fit in an arena-managed chunk (see the
|
|
.Dq K
|
|
option), are rounded up to the nearest run size.
|
|
Allocation requests that are too large to fit in an arena-managed chunk are
|
|
rounded up to the nearest multiple of the chunk size.
|
|
.Pp
|
|
Allocations are packed tightly together, which can be an issue for
|
|
multi-threaded applications.
|
|
If you need to assure that allocations do not suffer from cacheline sharing,
|
|
round your allocation requests up to the nearest multiple of the cacheline
|
|
size.
|
|
.Sh MALLCTL NAMESPACE
|
|
The following names are defined in the namespace accessible via the
|
|
.Fn mallctl*
|
|
functions.
|
|
Value types are specified in parentheses, and their readable/writable statuses
|
|
are encoded as rw, r-, -w, or --.
|
|
A name element encoded as <i> or <j> indicates an integer component, where the
|
|
integer varies from 0 to some upper value that must be determined via
|
|
introspection.
|
|
@roff_stats@In the case of
|
|
@roff_stats@.Dq stats.arenas.<i>.* ,
|
|
@roff_stats@<i> equal to
|
|
@roff_stats@.Dq arenas.narenas
|
|
@roff_stats@can be used to access the summation of statistics from all arenas.
|
|
.Bl -ohang
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "version (const char *) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Return the jemalloc version string.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "epoch (uint64_t) rw"
|
|
.Bd -ragged -offset indent -compact
|
|
If a value is passed in, refresh the data from which the
|
|
.Fn mallctl*
|
|
functions report values, and increment the epoch.
|
|
Return the current epoch.
|
|
This is useful for detecting whether another thread caused a refresh.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_tcache@.It Sy "tcache.flush (void) --"
|
|
@roff_tcache@.Bd -ragged -offset indent -compact
|
|
@roff_tcache@Flush calling thread's tcache.
|
|
@roff_tcache@This interface releases all cached objects and internal data
|
|
@roff_tcache@structures associated with the calling thread's thread-specific
|
|
@roff_tcache@cache.
|
|
@roff_tcache@Ordinarily, this interface need not be called, since automatic
|
|
@roff_tcache@periodic incremental garbage collection occurs, and the thread
|
|
@roff_tcache@cache is automatically discarded when a thread exits.
|
|
@roff_tcache@However, garbage collection is triggered by allocation activity,
|
|
@roff_tcache@so it is possible for a thread that stops allocating/deallocating
|
|
@roff_tcache@to retain its cache indefinitely, in which case the developer may
|
|
@roff_tcache@find manual flushing useful.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.debug (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-debug was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.dss (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-dss was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.dynamic_page_shift (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-dynamic-page-shift was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.fill (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-fill was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.lazy_lock (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-lazy-lock was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.prof (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-prof was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.prof_libgcc (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--disable-prof-libgcc was not specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.prof_libunwind (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-prof-libunwind was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.stats (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-stats was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.swap (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-swap was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.sysv (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-sysv was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.tcache (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--disable-tcache was not specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.tiny (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--disable-tiny was not specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.tls (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--disable-tls was not specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "config.xmalloc (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
--enable-xmalloc was specified during build configuration.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "opt.abort (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
See the
|
|
.Dq A
|
|
option.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_fill@.It Sy "opt.junk (bool) r-"
|
|
@roff_fill@.Bd -ragged -offset indent -compact
|
|
@roff_fill@See the
|
|
@roff_fill@.Dq J
|
|
@roff_fill@option.
|
|
@roff_fill@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_fill@.It Sy "opt.zero (bool) r-"
|
|
@roff_fill@.Bd -ragged -offset indent -compact
|
|
@roff_fill@See the
|
|
@roff_fill@.Dq Z
|
|
@roff_fill@option.
|
|
@roff_fill@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_xmalloc@.It Sy "opt.xmalloc (bool) r-"
|
|
@roff_xmalloc@.Bd -ragged -offset indent -compact
|
|
@roff_xmalloc@See the
|
|
@roff_xmalloc@.Dq X
|
|
@roff_xmalloc@option.
|
|
@roff_xmalloc@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_tcache@.It Sy "opt.tcache (bool) r-"
|
|
@roff_tcache@.Bd -ragged -offset indent -compact
|
|
@roff_tcache@See the
|
|
@roff_tcache@.Dq H
|
|
@roff_tcache@option.
|
|
@roff_tcache@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_tcache@.It Sy "opt.lg_tcache_gc_sweep (ssize_t) r-"
|
|
@roff_tcache@.Bd -ragged -offset indent -compact
|
|
@roff_tcache@See the
|
|
@roff_tcache@.Dq G
|
|
@roff_tcache@option.
|
|
@roff_tcache@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "opt.stats_print (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
See the
|
|
.Dq P
|
|
option.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_prof@.It Sy "opt.prof (bool) r-"
|
|
@roff_prof@.Bd -ragged -offset indent -compact
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq F
|
|
@roff_prof@option.
|
|
@roff_prof@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_prof@.It Sy "opt.lg_prof_bt_max (size_t) r-"
|
|
@roff_prof@.Bd -ragged -offset indent -compact
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq B
|
|
@roff_prof@option.
|
|
@roff_prof@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_prof@.It Sy "opt.lg_prof_interval (size_t) r-"
|
|
@roff_prof@.Bd -ragged -offset indent -compact
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq I
|
|
@roff_prof@option.
|
|
@roff_prof@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_prof@.It Sy "opt.prof_udump (bool) r-"
|
|
@roff_prof@.Bd -ragged -offset indent -compact
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq U
|
|
@roff_prof@option.
|
|
@roff_prof@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_prof@.It Sy "opt.prof_leak (bool) r-"
|
|
@roff_prof@.Bd -ragged -offset indent -compact
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq L
|
|
@roff_prof@option.
|
|
@roff_prof@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "opt.lg_qspace_max (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
See the
|
|
.Dq Q
|
|
option.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "opt.lg_cspace_max (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
See the
|
|
.Dq C
|
|
option.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "opt.lg_dirty_mult (ssize_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
See the
|
|
.Dq D
|
|
option.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "opt.lg_chunk (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
See the
|
|
.Dq K
|
|
option.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "opt.overcommit (bool) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
See the
|
|
.Dq O
|
|
option.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.narenas (unsigned) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Maximum number of arenas.
|
|
See the
|
|
.Dq N
|
|
option.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.initialized (bool *) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
An array of arenas.narenas booleans.
|
|
Each boolean indicates whether the corresponding arena is initialized.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.quantum (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Quantum size.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.cacheline (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Assumed cacheline size.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.subpage (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Subpage size class interval.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.pagesize (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Page size.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.chunksize (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Chunk size.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.tspace_min (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Minimum tiny size class.
|
|
Tiny size classes are powers of two.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.tspace_max (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Maximum tiny size class.
|
|
Tiny size classes are powers of two.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.qspace_min (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Minimum quantum-spaced size class.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.qspace_max (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Maximum quantum-spaced size class.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.cspace_min (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Minimum cacheline-spaced size class.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.cspace_max (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Maximum cacheline-spaced size class.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.sspace_min (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Minimum subpage-spaced size class.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.sspace_max (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Maximum subpage-spaced size class.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_tcache@.It Sy "arenas.tcache_max (size_t) r-"
|
|
@roff_tcache@.Bd -ragged -offset indent -compact
|
|
@roff_tcache@Maximum thread-cached size class.
|
|
@roff_tcache@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.ntbins (unsigned) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Number of tiny bin size classes.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.nqbins (unsigned) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Number of quantum-spaced bin size classes.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.ncbins (unsigned) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Number of cacheline-spaced bin size classes.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.nsbins (unsigned) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Number of subpage-spaced bin size classes.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.nbins (unsigned) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Total number of bin size classes.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_tcache@.It Sy "arenas.nhbins (unsigned) r-"
|
|
@roff_tcache@.Bd -ragged -offset indent -compact
|
|
@roff_tcache@Total number of thread cache bin size classes.
|
|
@roff_tcache@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.bin.<i>.size (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Maximum size supported by size class.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.bin.<i>.nregs (uint32_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Number of regions per page run.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.bin.<i>.run_size (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Number of bytes per page run.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.nlruns (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Total number of large size classes.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "arenas.lrun.<i>.size (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Maximum size supported by this large size class.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_prof@.It Sy "prof.dump (const char *) -w"
|
|
@roff_prof@.Bd -ragged -offset indent -compact
|
|
@roff_prof@Dump a memory profile to the specified file, or if NULL is specified,
|
|
@roff_prof@to a file according to the pattern
|
|
@roff_prof@.Pa <prefix>.<pid>.<seq>.m<mseq>.heap ,
|
|
@roff_prof@where
|
|
@roff_prof@.Pa <prefix>
|
|
@roff_prof@is controlled by the
|
|
@roff_prof@JEMALLOC_PROF_PREFIX
|
|
@roff_prof@environment variable.
|
|
@roff_prof@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_prof@.It Sy "prof.interval (uint64_t) r-"
|
|
@roff_prof@.Bd -ragged -offset indent -compact
|
|
@roff_prof@Average number of bytes allocated between inverval-based profile
|
|
@roff_prof@dumps.
|
|
@roff_prof@See the
|
|
@roff_prof@.Dq I
|
|
@roff_prof@option for additional information.
|
|
@roff_prof@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.allocated (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Total number of bytes allocated by the application.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.active (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Total number of bytes in active pages allocated by the application.
|
|
@roff_stats@This is a multiple of the page size, and greater than or equal to
|
|
@roff_stats@.Dq stats.allocated .
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.mapped (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Total number of bytes in chunks mapped on behalf of the application.
|
|
@roff_stats@This is a multiple of the chunk size, and is at least as large as
|
|
@roff_stats@.Dq stats.active .
|
|
@roff_stats@@roff_swap@This does not include inactive chunks backed by swap
|
|
@roff_stats@@roff_swap@files.
|
|
@roff_stats@@roff_dss@This does not include inactive chunks embedded in the DSS.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.chunks.current (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Total number of chunks actively mapped on behalf of the application.
|
|
@roff_stats@@roff_swap@This does not include inactive chunks backed by swap
|
|
@roff_stats@@roff_swap@files.
|
|
@roff_stats@@roff_dss@This does not include inactive chunks embedded in the DSS.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.chunks.total (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of chunks allocated.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.chunks.high (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Maximum number of active chunks at any time thus far.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.huge.allocated (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Number of bytes currently allocated by huge objects.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.huge.nmalloc (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of huge allocation requests.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.huge.ndalloc (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of huge deallocation requests.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "stats.arenas.<i>.pactive (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Number of pages in active runs.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.It Sy "stats.arenas.<i>.pdirty (size_t) r-"
|
|
.Bd -ragged -offset indent -compact
|
|
Number of pages within unused runs that are potentially dirty, and for which
|
|
.Fn madvise "..." "MADV_DONTNEED"
|
|
has not been called.
|
|
.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.mapped (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Number of mapped bytes.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.npurge (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Number of dirty page purge sweeps performed.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.nmadvise (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Number of
|
|
@roff_stats@.Fn madvise "..." "MADV_DONTNEED"
|
|
@roff_stats@calls made to purge dirty pages.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.npurged (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Number of pages purged.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.small.allocated (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Number of bytes currently allocated by small objects.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.small.nmalloc (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of allocation requests served by small bins.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.small.ndalloc (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of small objects returned to bins.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.small.nrequests (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of small allocation requests.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.large.allocated (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Number of bytes currently allocated by large objects.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.large.nmalloc (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of large allocation requests served directly by
|
|
@roff_stats@the arena.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.large.ndalloc (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of large deallocation requests served directly by
|
|
@roff_stats@the arena.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.large.nrequests (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of large allocation requests.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.bins.<j>.allocated (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Current number of bytes allocated by bin.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.bins.<j>.nmalloc (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of allocations served by bin.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.bins.<j>.ndalloc (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of allocations returned to bin.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.bins.<j>.nrequests (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of allocation requests.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@@roff_tcache@.It Sy "stats.arenas.<i>.bins.<j>.nfills (uint64_t) r-"
|
|
@roff_stats@@roff_tcache@.Bd -ragged -offset indent -compact
|
|
@roff_stats@@roff_tcache@Cumulative number of tcache fills.
|
|
@roff_stats@@roff_tcache@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@@roff_tcache@.It Sy "stats.arenas.<i>.bins.<j>.nflushes (uint64_t) r-"
|
|
@roff_stats@@roff_tcache@.Bd -ragged -offset indent -compact
|
|
@roff_stats@@roff_tcache@Cumulative number of tcache flushes.
|
|
@roff_stats@@roff_tcache@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.bins.<j>.nruns (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of runs created.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.bins.<j>.nreruns (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of times the current run from which to allocate
|
|
@roff_stats@changed.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.bins.<j>.highruns (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Maximum number of runs at any time thus far.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.bins.<j>.curruns (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Current number of runs.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.lruns.<j>.nmalloc (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of allocation requests for this size class served
|
|
@roff_stats@directly by the arena.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.lruns.<j>.ndalloc (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of deallocation requests for this size class
|
|
@roff_stats@served directly by the arena.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.lruns.<j>.nrequests (uint64_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Cumulative number of allocation requests for this size class.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.lruns.<j>.highruns (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Maximum number of runs at any time thus far for this size class.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@.It Sy "stats.arenas.<i>.lruns.<j>.curruns (size_t) r-"
|
|
@roff_stats@.Bd -ragged -offset indent -compact
|
|
@roff_stats@Current number of runs for this size class.
|
|
@roff_stats@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_stats@@roff_swap@.It Sy "swap.avail (size_t) r-"
|
|
@roff_stats@@roff_swap@.Bd -ragged -offset indent -compact
|
|
@roff_stats@@roff_swap@Number of swap file bytes that are currently not
|
|
@roff_stats@@roff_swap@associated with any chunk (i.e. mapped, but otherwise
|
|
@roff_stats@@roff_swap@completely unmanaged).
|
|
@roff_stats@@roff_swap@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_swap@.It Sy "swap.prezeroed (bool) rw"
|
|
@roff_swap@.Bd -ragged -offset indent -compact
|
|
@roff_swap@If true, the allocator assumes that the swap file(s) contain nothing
|
|
@roff_swap@but nil bytes.
|
|
@roff_swap@If this assumption is violated, allocator behavior is undefined.
|
|
@roff_swap@This value becomes read-only after
|
|
@roff_swap@.Dq swap.fds
|
|
@roff_swap@is successfully written to.
|
|
@roff_swap@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_swap@.It Sy "swap.nfds (size_t) r-"
|
|
@roff_swap@.Bd -ragged -offset indent -compact
|
|
@roff_swap@Number of file descriptors in use for swap.
|
|
@roff_swap@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
@roff_swap@.It Sy "swap.fds (int *) r-"
|
|
@roff_swap@.Bd -ragged -offset indent -compact
|
|
@roff_swap@When written to, the files associated with the specified file
|
|
@roff_swap@descriptors are contiguously mapped via
|
|
@roff_swap@.Xr mmap 2 .
|
|
@roff_swap@The resulting virtual memory region is preferred over anonymous
|
|
@roff_swap@.Xr mmap 2
|
|
@roff_swap@@roff_dss@and
|
|
@roff_swap@@roff_dss@.Xr sbrk 2
|
|
@roff_swap@memory.
|
|
@roff_swap@Note that if a file's size is not a multiple of the page size, it is
|
|
@roff_swap@automatically truncated to the nearest page size multiple.
|
|
@roff_swap@See the
|
|
@roff_swap@.Dq swap.prezeroed
|
|
@roff_swap@interface for specifying that the files are pre-zeroed.
|
|
@roff_swap@.Ed
|
|
.\"-----------------------------------------------------------------------------
|
|
.El
|
|
.Sh DEBUGGING MALLOC PROBLEMS
|
|
The first thing to do is to set the
|
|
.Dq A
|
|
option.
|
|
This option forces a coredump (if possible) at the first sign of trouble,
|
|
rather than the normal policy of trying to continue if at all possible.
|
|
.Pp
|
|
It is probably also a good idea to recompile the program with suitable
|
|
options and symbols for debugger support.
|
|
.Pp
|
|
@roff_fill@If the program starts to give unusual results, coredump or generally
|
|
@roff_fill@behave differently without emitting any of the messages mentioned in
|
|
@roff_fill@the next section, it is likely because it depends on the storage
|
|
@roff_fill@being filled with zero bytes.
|
|
@roff_fill@Try running it with the
|
|
@roff_fill@.Dq Z
|
|
@roff_fill@option set;
|
|
@roff_fill@if that improves the situation, this diagnosis has been confirmed.
|
|
@roff_fill@If the program still misbehaves,
|
|
@roff_fill@the likely problem is accessing memory outside the allocated area.
|
|
@roff_fill@.Pp
|
|
@roff_fill@Alternatively, if the symptoms are not easy to reproduce, setting the
|
|
@roff_fill@.Dq J
|
|
@roff_fill@option may help provoke the problem.
|
|
@roff_fill@.Pp
|
|
Unfortunately this implementation does not provide much detail about
|
|
the problems it detects; the performance impact for storing such information
|
|
would be prohibitive.
|
|
There are a number of allocator implementations available on the Internet
|
|
which focus on detecting and pinpointing problems by trading performance for
|
|
extra sanity checks and detailed diagnostics.
|
|
.Sh DIAGNOSTIC MESSAGES
|
|
If any of the memory allocation/deallocation functions detect an error or
|
|
warning condition, a message will be printed to file descriptor
|
|
.Dv STDERR_FILENO .
|
|
Errors will result in the process dumping core.
|
|
If the
|
|
.Dq A
|
|
option is set, all warnings are treated as errors.
|
|
.Pp
|
|
The
|
|
.Va @jemalloc_prefix@malloc_message
|
|
variable allows the programmer to override the function which emits the text
|
|
strings forming the errors and warnings if for some reason the
|
|
.Dv STDERR_FILENO
|
|
file descriptor is not suitable for this.
|
|
.Va @jemalloc_prefix@malloc_message
|
|
takes the
|
|
.Fa cbopaque
|
|
pointer argument that is
|
|
.Dv NULL
|
|
unless overridden by the arguments in a call to
|
|
.Fn @jemalloc_prefix@malloc_stats_print ,
|
|
followed by a string pointer.
|
|
Please note that doing anything which tries to allocate memory in this function
|
|
is likely to result in a crash or deadlock.
|
|
.Pp
|
|
All messages are prefixed by
|
|
.Dq <jemalloc>: .
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn @jemalloc_prefix@malloc
|
|
and
|
|
.Fn @jemalloc_prefix@calloc
|
|
functions return a pointer to the allocated memory if successful; otherwise
|
|
a
|
|
.Dv NULL
|
|
pointer is returned and
|
|
.Va errno
|
|
is set to
|
|
.Er ENOMEM .
|
|
.Pp
|
|
The
|
|
.Fn @jemalloc_prefix@posix_memalign
|
|
function returns the value 0 if successful; otherwise it returns an error value.
|
|
The
|
|
.Fn @jemalloc_prefix@posix_memalign
|
|
function will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fa alignment
|
|
parameter is not a power of 2 at least as large as
|
|
.Fn sizeof "void *" .
|
|
.It Bq Er ENOMEM
|
|
Memory allocation error.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Fn @jemalloc_prefix@realloc
|
|
function returns a pointer, possibly identical to
|
|
.Fa ptr ,
|
|
to the allocated memory
|
|
if successful; otherwise a
|
|
.Dv NULL
|
|
pointer is returned, and
|
|
.Va errno
|
|
is set to
|
|
.Er ENOMEM
|
|
if the error was the result of an allocation failure.
|
|
The
|
|
.Fn @jemalloc_prefix@realloc
|
|
function always leaves the original buffer intact
|
|
when an error occurs.
|
|
.Pp
|
|
The
|
|
.Fn @jemalloc_prefix@free
|
|
function returns no value.
|
|
.Pp
|
|
The
|
|
.Fn @jemalloc_prefix@malloc_usable_size
|
|
function returns the usable size of the allocation pointed to by
|
|
.Fa ptr .
|
|
.Pp
|
|
The
|
|
.Fn @jemalloc_prefix@mallctl ,
|
|
.Fn @jemalloc_prefix@mallctlnametomib ,
|
|
and
|
|
.Fn @jemalloc_prefix@mallctlbymib
|
|
functions return 0 on success; otherwise they return an error value.
|
|
The functions will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINVAL
|
|
.Fa newp
|
|
is
|
|
.Dv non-NULL ,
|
|
and
|
|
.Fa newlen
|
|
is too large or too small.
|
|
Alternatively,
|
|
.Fa *oldlenp
|
|
is too large or too small; in this case as much data as possible are read
|
|
despite the error.
|
|
.It Bq Er ENOMEM
|
|
.Fa *oldlenp
|
|
is too short to hold the requested value.
|
|
.It Bq Er ENOENT
|
|
.Fa name
|
|
or
|
|
.Fa mib
|
|
specifies an unknown/invalid value.
|
|
.It Bq Er EPERM
|
|
Attempt to read or write void value, or attempt to write read-only value.
|
|
.It Bq Er EAGAIN
|
|
A memory allocation failure occurred.
|
|
.It Bq Er EFAULT
|
|
An interface with side effects failed in some way not directly related to
|
|
.Fn mallctl*
|
|
read/write processing.
|
|
.El
|
|
.Sh ENVIRONMENT
|
|
The following environment variables affect the execution of the allocation
|
|
functions:
|
|
@roff_prof@.Bl -tag -width ".Ev JEMALLOC_PROF_PREFIX"
|
|
@roff_no_prof@.Bl -tag -width ".Ev JEMALLOC_OPTIONS"
|
|
.It Ev JEMALLOC_OPTIONS
|
|
If the environment variable
|
|
.Ev JEMALLOC_OPTIONS
|
|
is set, the characters it contains will be interpreted as flags to the
|
|
allocation functions.
|
|
@roff_prof@.It Ev JEMALLOC_PROF_PREFIX
|
|
@roff_prof@If the environment variable
|
|
@roff_prof@.Ev JEMALLOC_PROF_PREFIX
|
|
@roff_prof@is set, use it as the filename prefix for profile dumps; otherwise
|
|
@roff_prof@use
|
|
@roff_prof@.Pa jeprof
|
|
@roff_prof@as the prefix.
|
|
.El
|
|
.Sh EXAMPLES
|
|
To dump core whenever a problem occurs:
|
|
.Pp
|
|
.Bd -literal -offset indent
|
|
ln -s 'A' /etc/jemalloc.conf
|
|
.Ed
|
|
.Pp
|
|
To specify in the source a chunk size that is twice the default:
|
|
.Bd -literal -offset indent
|
|
@jemalloc_prefix@malloc_options = "K";
|
|
.Ed
|
|
.Sh SEE ALSO
|
|
.Xr madvise 2 ,
|
|
.Xr mmap 2 ,
|
|
@roff_dss@.Xr sbrk 2 ,
|
|
.Xr alloca 3 ,
|
|
.Xr atexit 3 ,
|
|
.Xr getpagesize 3
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn @jemalloc_prefix@malloc ,
|
|
.Fn @jemalloc_prefix@calloc ,
|
|
.Fn @jemalloc_prefix@realloc
|
|
and
|
|
.Fn @jemalloc_prefix@free
|
|
functions conform to
|
|
.St -isoC .
|
|
.Pp
|
|
The
|
|
.Fn @jemalloc_prefix@posix_memalign
|
|
function conforms to
|
|
.St -p1003.1-2001 .
|