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diff --git a/man5/slabinfo.5 b/man5/slabinfo.5 new file mode 100644 index 000000000..ec53777fc --- /dev/null +++ b/man5/slabinfo.5 @@ -0,0 +1,111 @@ +.\" Copyright (c) 2001 Andreas Dilger (adilger@turbolinux.com) +.\" +.\" Permission is granted to make and distribute verbatim copies of this +.\" manual provided the copyright notice and this permission notice are +.\" preserved on all copies. +.\" +.\" Permission is granted to copy and distribute modified versions of this +.\" manual under the conditions for verbatim copying, provided that the +.\" entire resulting derived work is distributed under the terms of a +.\" permission notice identical to this one. +.\" +.\" Since the Linux kernel and libraries are constantly changing, this +.\" manual page may be incorrect or out-of-date. The author(s) assume no +.\" responsibility for errors or omissions, or for damages resulting from +.\" the use of the information contained herein. The author(s) may not +.\" have taken the same level of care in the production of this manual, +.\" which is licensed free of charge, as they might when working +.\" professionally. +.\" +.\" Formatted or processed versions of this manual, if unaccompanied by +.\" the source, must acknowledge the copyright and authors of this work. +.\" +.TH SLABINFO 5 2001-06-19 "" "Linux manual" +.SH NAME +/proc/slabinfo \- Kernel slab allocator statistics +.SH SYNOPSIS +.B cat /proc/slabinfo +.SH DESCRIPTION +Frequently used objects in the Linux kernel +(buffer heads, inodes, dentries, etc.) +have their own cache. The file +.I /proc/slabinfo +gives statistics. For example: +.LP +.RS +.nf +% cat /proc/slabinfo +slabinfo - version: 1.1 +kmem_cache 60 78 100 2 2 1 +blkdev_requests 5120 5120 96 128 128 1 +mnt_cache 20 40 96 1 1 1 +inode_cache 7005 14792 480 1598 1849 1 +dentry_cache 5469 5880 128 183 196 1 +filp 726 760 96 19 19 1 +buffer_head 67131 71240 96 1776 1781 1 +vm_area_struct 1204 1652 64 23 28 1 +\&... +size-8192 1 17 8192 1 17 2 +size-4096 41 73 4096 41 73 1 +\&... +.fi +.RE +.LP +For each slab cache, the cache name, the number of currently +active objects, the total number of available objects, the +size of each object in bytes, the number of pages with at +least one active object, the total number of allocated pages, +and the number of pages per slab are given. + +Note that because of object alignment and slab cache overhead, +objects are not normally packed tightly into pages. Pages with +even one in-use object are considered in-use and cannot be +freed. + +Kernels compiled with slab cache statistics will also have +"(statistics)" in the first line of output, and will have 5 +additional columns, namely: the high water mark of active +objects; the number of times objects have been allocated; +the number of times the cache has grown (new pages added +to this cache); the number of times the cache has been +reaped (unused pages removed from this cache); and the +number of times there was an error allocating new pages +to this cache. If slab cache statistics are not enabled +for this kernel, these columns will not be shown. + +SMP systems will also have "(SMP)" in the first line of +output, and will have two additional columns for each slab, +reporting the slab allocation policy for the CPU-local +cache (to reduce the need for inter-CPU synchronization +when allocating objects from the cache). The first column +is the per-CPU limit: the maximum number of objects that +will be cached for each CPU. The second column is the +batchcount: the maximum number of free objects in the +global cache that will be transferred to the per-CPU cache +if it is empty, or the number of objects to be returned +to the global cache if the per-CPU cache is full. + +If both slab cache statistics and SMP are defined, there +will be four additional columns, reporting the per-CPU +cache statistics. The first two are the per-CPU cache +allocation hit and miss counts: the number of times an +object was or was not available in the per-CPU cache +for allocation. The next two are the per-CPU cache free +hit and miss counts: the number of times a freed object +could or could not fit within the per-CPU cache limit, +before flushing objects to the global cache. + +It is possible to tune the SMP per-CPU slab cache limit +and batchcount via: + +.nf +echo "\fIcache_name limit batchcount\fP" > /proc/slabinfo +.fi + +.SH AVAILABILITY +.I /proc/slabinfo +exists since Linux 2.1.23. +SMP per-CPU caches exist since Linux 2.4.0-test3. + +.SH FILES +.I <linux/slab.h> |