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SLABINFO(5)			    Linux Programmer's Manual			      SLABINFO(5)

NAME
       /proc/slabinfo - kernel slab allocator statistics

SYNOPSIS
       cat /proc/slabinfo

DESCRIPTION
       Frequently  used  objects in the Linux kernel (buffer heads, inodes, dentries, etc.)  have
       their own cache.  The file /proc/slabinfo gives statistics.  For example:

	   % 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
	   ...

       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 allo-
       cating 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 addi-
       tional 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 num-
       ber 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:

	   echo "cache_name limit batchcount" > /proc/slabinfo

FILES
       <linux/slab.h>

VERSIONS
       /proc/slabinfo  exists  since  Linux  2.1.23.   SMP  per-CPU  caches  exist  since   Linux
       2.4.0-test3.

NOTES
       Since  Linux 2.6.16 the file /proc/slabinfo is present only if the CONFIG_SLAB kernel con-
       figuration option is enabled.

COLOPHON
       This page is part of release 3.55 of the Linux man-pages project.  A  description  of  the
       project,     and    information	  about    reporting	bugs,	 can	be    found    at
       http://www.kernel.org/doc/man-pages/.

					    2007-09-30				      SLABINFO(5)
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