What: /sys/kernel/slab
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The /sys/kernel/slab directory contains a snapshot of the
internal state of the SLUB allocator for each cache. Certain
files may be modified to change the behavior of the cache (and
any cache it aliases, if any).
Users: kernel memory tuning tools
What: /sys/kernel/slab/cache/aliases
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The aliases file is read-only and specifies how many caches
have merged into this cache.
What: /sys/kernel/slab/cache/align
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The align file is read-only and specifies the cache's object
alignment in bytes.
What: /sys/kernel/slab/cache/alloc_calls
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The alloc_calls file is read-only and lists the kernel code
locations from which allocations for this cache were performed.
The alloc_calls file only contains information if debugging is
enabled for that cache (see Documentation/vm/slub.txt).
What: /sys/kernel/slab/cache/alloc_fastpath
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The alloc_fastpath file is read-only and specifies how many
objects have been allocated using the fast path.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/alloc_from_partial
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The alloc_from_partial file is read-only and specifies how
many times a cpu slab has been full and it has been refilled
by using a slab from the list of partially used slabs.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/alloc_refill
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The alloc_refill file is read-only and specifies how many
times the per-cpu freelist was empty but there were objects
available as the result of remote cpu frees.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/alloc_slab
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The alloc_slab file is read-only and specifies how many times
a new slab had to be allocated from the page allocator.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/alloc_slowpath
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The alloc_slowpath file is read-only and specifies how many
objects have been allocated using the slow path because of a
refill or allocation from a partial or new slab.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/cache_dma
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The cache_dma file is read-only and specifies whether objects
are from ZONE_DMA.
Available when CONFIG_ZONE_DMA is enabled.
What: /sys/kernel/slab/cache/cpu_slabs
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The cpu_slabs file is read-only and displays how many cpu slabs
are active and their NUMA locality.
What: /sys/kernel/slab/cache/cpuslab_flush
Date: April 2009
KernelVersion: 2.6.31
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file cpuslab_flush is read-only and specifies how many
times a cache's cpu slabs have been flushed as the result of
destroying or shrinking a cache, a cpu going offline, or as
the result of forcing an allocation from a certain node.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/ctor
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The ctor file is read-only and specifies the cache's object
constructor function, which is invoked for each object when a
new slab is allocated.
What: /sys/kernel/slab/cache/deactivate_empty
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file deactivate_empty is read-only and specifies how many
times an empty cpu slab was deactivated.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/deactivate_full
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file deactivate_full is read-only and specifies how many
times a full cpu slab was deactivated.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/deactivate_remote_frees
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file deactivate_remote_frees is read-only and specifies how
many times a cpu slab has been deactivated and contained free
objects that were freed remotely.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/deactivate_to_head
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file deactivate_to_head is read-only and specifies how
many times a partial cpu slab was deactivated and added to the
head of its node's partial list.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/deactivate_to_tail
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file deactivate_to_tail is read-only and specifies how
many times a partial cpu slab was deactivated and added to the
tail of its node's partial list.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/destroy_by_rcu
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The destroy_by_rcu file is read-only and specifies whether
slabs (not objects) are freed by rcu.
What: /sys/kernel/slab/cache/free_add_partial
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file free_add_partial is read-only and specifies how many
times an object has been freed in a full slab so that it had to
added to its node's partial list.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/free_calls
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The free_calls file is read-only and lists the locations of
object frees if slab debugging is enabled (see
Documentation/vm/slub.txt).
What: /sys/kernel/slab/cache/free_fastpath
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The free_fastpath file is read-only and specifies how many
objects have been freed using the fast path because it was an
object from the cpu slab.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/free_frozen
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The free_frozen file is read-only and specifies how many
objects have been freed to a frozen slab (i.e. a remote cpu
slab).
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/free_remove_partial
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file free_remove_partial is read-only and specifies how
many times an object has been freed to a now-empty slab so
that it had to be removed from its node's partial list.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/free_slab
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The free_slab file is read-only and specifies how many times an
empty slab has been freed back to the page allocator.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/free_slowpath
Date: February 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The free_slowpath file is read-only and specifies how many
objects have been freed using the slow path (i.e. to a full or
partial slab).
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/hwcache_align
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The hwcache_align file is read-only and specifies whether
objects are aligned on cachelines.
What: /sys/kernel/slab/cache/min_partial
Date: February 2009
KernelVersion: 2.6.30
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
David Rientjes <rientjes@google.com>
Description:
The min_partial file specifies how many empty slabs shall
remain on a node's partial list to avoid the overhead of
allocating new slabs. Such slabs may be reclaimed by utilizing
the shrink file.
What: /sys/kernel/slab/cache/object_size
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The object_size file is read-only and specifies the cache's
object size.
What: /sys/kernel/slab/cache/objects
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The objects file is read-only and displays how many objects are
active and from which nodes they are from.
What: /sys/kernel/slab/cache/objects_partial
Date: April 2008
KernelVersion: 2.6.26
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The objects_partial file is read-only and displays how many
objects are on partial slabs and from which nodes they are
from.
What: /sys/kernel/slab/cache/objs_per_slab
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file objs_per_slab is read-only and specifies how many
objects may be allocated from a single slab of the order
specified in /sys/kernel/slab/cache/order.
What: /sys/kernel/slab/cache/order
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The order file specifies the page order at which new slabs are
allocated. It is writable and can be changed to increase the
number of objects per slab. If a slab cannot be allocated
because of fragmentation, SLUB will retry with the minimum order
possible depending on its characteristics.
What: /sys/kernel/slab/cache/order_fallback
Date: April 2008
KernelVersion: 2.6.26
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file order_fallback is read-only and specifies how many
times an allocation of a new slab has not been possible at the
cache's order and instead fallen back to its minimum possible
order.
Available when CONFIG_SLUB_STATS is enabled.
What: /sys/kernel/slab/cache/partial
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The partial file is read-only and displays how long many
partial slabs there are and how long each node's list is.
What: /sys/kernel/slab/cache/poison
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The poison file specifies whether objects should be poisoned
when a new slab is allocated.
What: /sys/kernel/slab/cache/reclaim_account
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The reclaim_account file specifies whether the cache's objects
are reclaimable (and grouped by their mobility).
What: /sys/kernel/slab/cache/red_zone
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The red_zone file specifies whether the cache's objects are red
zoned.
What: /sys/kernel/slab/cache/remote_node_defrag_ratio
Date: January 2008
KernelVersion: 2.6.25
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The file remote_node_defrag_ratio specifies the percentage of
times SLUB will attempt to refill the cpu slab with a partial
slab from a remote node as opposed to allocating a new slab on
the local node. This reduces the amount of wasted memory over
the entire system but can be expensive.
Available when CONFIG_NUMA is enabled.
What: /sys/kernel/slab/cache/sanity_checks
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The sanity_checks file specifies whether expensive checks
should be performed on free and, at minimum, enables double free
checks. Caches that enable sanity_checks cannot be merged with
caches that do not.
What: /sys/kernel/slab/cache/shrink
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The shrink file is written when memory should be reclaimed from
a cache. Empty partial slabs are freed and the partial list is
sorted so the slabs with the fewest available objects are used
first.
What: /sys/kernel/slab/cache/slab_size
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The slab_size file is read-only and specifies the object size
with metadata (debugging information and alignment) in bytes.
What: /sys/kernel/slab/cache/slabs
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The slabs file is read-only and displays how long many slabs
there are (both cpu and partial) and from which nodes they are
from.
What: /sys/kernel/slab/cache/store_user
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The store_user file specifies whether the location of
allocation or free should be tracked for a cache.
What: /sys/kernel/slab/cache/total_objects
Date: April 2008
KernelVersion: 2.6.26
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The total_objects file is read-only and displays how many total
objects a cache has and from which nodes they are from.
What: /sys/kernel/slab/cache/trace
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
The trace file specifies whether object allocations and frees
should be traced.
What: /sys/kernel/slab/cache/validate
Date: May 2007
KernelVersion: 2.6.22
Contact: Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>
Description:
Writing to the validate file causes SLUB to traverse all of its
cache's objects and check the validity of metadata.
