2004-11-03 13:51:07 +00:00
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.\" Copyright (c) 2001 Andreas Dilger (adilger@turbolinux.com)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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2012-08-16 08:48:24 +00:00
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.\" FIXME Over time, the slabinfo format has gone through
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.\" version changes. These should be documented:
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.\"
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.\" slabinfo 1.0 - Linux 2.2 (precisely: 2.1.23)
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.\" slabinfo 1.1 - Linux 2.4 (precisely: 2.4.0-test3)
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.\" slabinfo 1.2 - Linux 2.5.45
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.\" slabinfo 2.0 - Linux 2.6 (precisely: 2.5.71)
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.\" slabinfo 2.1 - Linux 2.6.10
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2012-10-15 09:13:31 +00:00
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.\"
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2007-09-27 18:27:13 +00:00
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.TH SLABINFO 5 2007-09-30 "" "Linux Programmer's Manual"
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2004-11-03 13:51:07 +00:00
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.SH NAME
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intro.1, add_key.2, get_mempolicy.2, get_thread_area.2, intro.2, keyctl.2, mbind.2, request_key.2, set_thread_area.2, clock.3, cmsg.3, getcwd.3, getpw.3, intro.3, malloc.3, posix_memalign.3, shm_open.3, sleep.3, sysconf.3, intro.4, sd.4, intro.5, locale.5, slabinfo.5, intro.6, boot.7, bootparam.7, futex.7, glob.7, hier.7, intro.7, libc.7, locale.7, mq_overview.7, netlink.7, sem_overview.7, shm_overview.7, unix.7, intro.8: Global fix: Use consistent capitalization in NAME section
The line(s) in the NAME section should only use capitals
where English usage dictates that. Otherwise, use
lowercase throughout.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-10-21 06:29:13 +00:00
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/proc/slabinfo \- kernel slab allocator statistics
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2004-11-03 13:51:07 +00:00
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.SH SYNOPSIS
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.B cat /proc/slabinfo
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.SH DESCRIPTION
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Frequently used objects in the Linux kernel
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(buffer heads, inodes, dentries, etc.)
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2007-04-12 22:42:49 +00:00
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have their own cache.
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The file
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2004-11-03 13:51:07 +00:00
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.I /proc/slabinfo
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2007-04-12 22:42:49 +00:00
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gives statistics.
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For example:
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2004-11-03 13:51:07 +00:00
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.LP
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2007-12-19 07:19:23 +00:00
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.in +4n
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2004-11-03 13:51:07 +00:00
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.nf
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% cat /proc/slabinfo
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2005-07-06 12:57:38 +00:00
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slabinfo \- version: 1.1
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2004-11-03 13:51:07 +00:00
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kmem_cache 60 78 100 2 2 1
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blkdev_requests 5120 5120 96 128 128 1
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mnt_cache 20 40 96 1 1 1
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inode_cache 7005 14792 480 1598 1849 1
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dentry_cache 5469 5880 128 183 196 1
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filp 726 760 96 19 19 1
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buffer_head 67131 71240 96 1776 1781 1
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vm_area_struct 1204 1652 64 23 28 1
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\&...
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size-8192 1 17 8192 1 17 2
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size-4096 41 73 4096 41 73 1
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\&...
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.fi
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2007-12-19 07:19:23 +00:00
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.in
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2004-11-03 13:51:07 +00:00
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.LP
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For each slab cache, the cache name, the number of currently
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active objects, the total number of available objects, the
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size of each object in bytes, the number of pages with at
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least one active object, the total number of allocated pages,
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and the number of pages per slab are given.
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Note that because of object alignment and slab cache overhead,
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2007-04-12 22:42:49 +00:00
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objects are not normally packed tightly into pages.
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2007-09-27 18:27:13 +00:00
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Pages with even one in-use object are considered in-use and cannot be
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2004-11-03 13:51:07 +00:00
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freed.
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Kernels compiled with slab cache statistics will also have
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"(statistics)" in the first line of output, and will have 5
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additional columns, namely: the high water mark of active
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objects; the number of times objects have been allocated;
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the number of times the cache has grown (new pages added
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to this cache); the number of times the cache has been
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reaped (unused pages removed from this cache); and the
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number of times there was an error allocating new pages
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to this cache.
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If slab cache statistics are not enabled
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2004-11-03 13:51:07 +00:00
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for this kernel, these columns will not be shown.
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SMP systems will also have "(SMP)" in the first line of
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output, and will have two additional columns for each slab,
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reporting the slab allocation policy for the CPU-local
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cache (to reduce the need for inter-CPU synchronization
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when allocating objects from the cache).
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The first column is the per-CPU limit: the maximum number of objects that
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will be cached for each CPU.
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The second column is the
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2004-11-03 13:51:07 +00:00
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batchcount: the maximum number of free objects in the
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global cache that will be transferred to the per-CPU cache
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if it is empty, or the number of objects to be returned
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to the global cache if the per-CPU cache is full.
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If both slab cache statistics and SMP are defined, there
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will be four additional columns, reporting the per-CPU
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cache statistics.
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The first two are the per-CPU cache
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allocation hit and miss counts: the number of times an
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object was or was not available in the per-CPU cache
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2007-04-12 22:42:49 +00:00
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for allocation.
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The next two are the per-CPU cache free
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2004-11-03 13:51:07 +00:00
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hit and miss counts: the number of times a freed object
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could or could not fit within the per-CPU cache limit,
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before flushing objects to the global cache.
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It is possible to tune the SMP per-CPU slab cache limit
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and batchcount via:
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2007-12-19 07:19:23 +00:00
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.in +4n
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2004-11-03 13:51:07 +00:00
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.nf
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echo "\fIcache_name limit batchcount\fP" > /proc/slabinfo
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.fi
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2007-12-19 07:19:23 +00:00
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.in
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2007-05-19 04:30:20 +00:00
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.SH FILES
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.I <linux/slab.h>
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2007-05-16 04:53:05 +00:00
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.SH VERSIONS
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2004-11-03 13:51:07 +00:00
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.I /proc/slabinfo
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exists since Linux 2.1.23.
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SMP per-CPU caches exist since Linux 2.4.0-test3.
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2007-09-27 18:27:13 +00:00
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.SH NOTES
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2007-11-15 03:28:33 +00:00
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Since Linux 2.6.16 the file
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.I /proc/slabinfo
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2007-12-22 22:18:14 +00:00
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is only present if the
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.B CONFIG_SLAB
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kernel configuration option is enabled.
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