Documentation/ABI/testing/sysfs-kernel-slab

   1 What:           /sys/kernel/slab
   2 Date:           May 2007
   3 KernelVersion:  2.6.22
   4 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
   5                 Christoph Lameter <cl@linux-foundation.org>
   6 Description:
   7                 The /sys/kernel/slab directory contains a snapshot of the
   8                 internal state of the SLUB allocator for each cache.  Certain
   9                 files may be modified to change the behavior of the cache (and
  10                 any cache it aliases, if any).
  11 Users:          kernel memory tuning tools
  12
  13 What:           /sys/kernel/slab/cache/aliases
  14 Date:           May 2007
  15 KernelVersion:  2.6.22
  16 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
  17                 Christoph Lameter <cl@linux-foundation.org>
  18 Description:
  19                 The aliases file is read-only and specifies how many caches
  20                 have merged into this cache.
  21
  22 What:           /sys/kernel/slab/cache/align
  23 Date:           May 2007
  24 KernelVersion:  2.6.22
  25 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
  26                 Christoph Lameter <cl@linux-foundation.org>
  27 Description:
  28                 The align file is read-only and specifies the cache's object
  29                 alignment in bytes.
  30
  31 What:           /sys/kernel/slab/cache/alloc_calls
  32 Date:           May 2007
  33 KernelVersion:  2.6.22
  34 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
  35                 Christoph Lameter <cl@linux-foundation.org>
  36 Description:
  37                 The alloc_calls file is read-only and lists the kernel code
  38                 locations from which allocations for this cache were performed.
  39                 The alloc_calls file only contains information if debugging is
  40                 enabled for that cache (see Documentation/vm/slub.txt).
  41
  42 What:           /sys/kernel/slab/cache/alloc_fastpath
  43 Date:           February 2008
  44 KernelVersion:  2.6.25
  45 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
  46                 Christoph Lameter <cl@linux-foundation.org>
  47 Description:
  48                 The alloc_fastpath file shows how many objects have been
  49                 allocated using the fast path.  It can be written to clear the
  50                 current count.
  51                 Available when CONFIG_SLUB_STATS is enabled.
  52
  53 What:           /sys/kernel/slab/cache/alloc_from_partial
  54 Date:           February 2008
  55 KernelVersion:  2.6.25
  56 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
  57                 Christoph Lameter <cl@linux-foundation.org>
  58 Description:
  59                 The alloc_from_partial file shows how many times a cpu slab has
  60                 been full and it has been refilled by using a slab from the list
  61                 of partially used slabs.  It can be written to clear the current
  62                 count.
  63                 Available when CONFIG_SLUB_STATS is enabled.
  64
  65 What:           /sys/kernel/slab/cache/alloc_refill
  66 Date:           February 2008
  67 KernelVersion:  2.6.25
  68 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
  69                 Christoph Lameter <cl@linux-foundation.org>
  70 Description:
  71                 The alloc_refill file shows how many times the per-cpu freelist
  72                 was empty but there were objects available as the result of
  73                 remote cpu frees.  It can be written to clear the current count.
  74                 Available when CONFIG_SLUB_STATS is enabled.
  75
  76 What:           /sys/kernel/slab/cache/alloc_slab
  77 Date:           February 2008
  78 KernelVersion:  2.6.25
  79 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
  80                 Christoph Lameter <cl@linux-foundation.org>
  81 Description:
  82                 The alloc_slab file is shows how many times a new slab had to
  83                 be allocated from the page allocator.  It can be written to
  84                 clear the current count.
  85                 Available when CONFIG_SLUB_STATS is enabled.
  86
  87 What:           /sys/kernel/slab/cache/alloc_slowpath
  88 Date:           February 2008
  89 KernelVersion:  2.6.25
  90 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
  91                 Christoph Lameter <cl@linux-foundation.org>
  92 Description:
  93                 The alloc_slowpath file shows how many objects have been
  94                 allocated using the slow path because of a refill or
  95                 allocation from a partial or new slab.  It can be written to
  96                 clear the current count.
  97                 Available when CONFIG_SLUB_STATS is enabled.
  98
  99 What:           /sys/kernel/slab/cache/cache_dma
 100 Date:           May 2007
 101 KernelVersion:  2.6.22
 102 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 103                 Christoph Lameter <cl@linux-foundation.org>
 104 Description:
 105                 The cache_dma file is read-only and specifies whether objects
 106                 are from ZONE_DMA.
 107                 Available when CONFIG_ZONE_DMA is enabled.
 108
 109 What:           /sys/kernel/slab/cache/cpu_slabs
 110 Date:           May 2007
 111 KernelVersion:  2.6.22
 112 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 113                 Christoph Lameter <cl@linux-foundation.org>
 114 Description:
 115                 The cpu_slabs file is read-only and displays how many cpu slabs
 116                 are active and their NUMA locality.
 117
 118 What:           /sys/kernel/slab/cache/cpuslab_flush
 119 Date:           April 2009
 120 KernelVersion:  2.6.31
 121 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 122                 Christoph Lameter <cl@linux-foundation.org>
 123 Description:
 124                 The file cpuslab_flush shows how many times a cache's cpu slabs
 125                 have been flushed as the result of destroying or shrinking a
 126                 cache, a cpu going offline, or as the result of forcing an
 127                 allocation from a certain node.  It can be written to clear the
 128                 current count.
 129                 Available when CONFIG_SLUB_STATS is enabled.
 130
 131 What:           /sys/kernel/slab/cache/ctor
 132 Date:           May 2007
 133 KernelVersion:  2.6.22
 134 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 135                 Christoph Lameter <cl@linux-foundation.org>
 136 Description:
 137                 The ctor file is read-only and specifies the cache's object
 138                 constructor function, which is invoked for each object when a
 139                 new slab is allocated.
 140
 141 What:           /sys/kernel/slab/cache/deactivate_empty
 142 Date:           February 2008
 143 KernelVersion:  2.6.25
 144 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 145                 Christoph Lameter <cl@linux-foundation.org>
 146 Description:
 147                 The deactivate_empty file shows how many times an empty cpu slab
 148                 was deactivated.  It can be written to clear the current count.
 149                 Available when CONFIG_SLUB_STATS is enabled.
 150
 151 What:           /sys/kernel/slab/cache/deactivate_full
 152 Date:           February 2008
 153 KernelVersion:  2.6.25
 154 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 155                 Christoph Lameter <cl@linux-foundation.org>
 156 Description:
 157                 The deactivate_full file shows how many times a full cpu slab
 158                 was deactivated.  It can be written to clear the current count.
 159                 Available when CONFIG_SLUB_STATS is enabled.
 160
 161 What:           /sys/kernel/slab/cache/deactivate_remote_frees
 162 Date:           February 2008
 163 KernelVersion:  2.6.25
 164 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 165                 Christoph Lameter <cl@linux-foundation.org>
 166 Description:
 167                 The deactivate_remote_frees file shows how many times a cpu slab
 168                 has been deactivated and contained free objects that were freed
 169                 remotely.  It can be written to clear the current count.
 170                 Available when CONFIG_SLUB_STATS is enabled.
 171
 172 What:           /sys/kernel/slab/cache/deactivate_to_head
 173 Date:           February 2008
 174 KernelVersion:  2.6.25
 175 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 176                 Christoph Lameter <cl@linux-foundation.org>
 177 Description:
 178                 The deactivate_to_head file shows how many times a partial cpu
 179                 slab was deactivated and added to the head of its node's partial
 180                 list.  It can be written to clear the current count.
 181                 Available when CONFIG_SLUB_STATS is enabled.
 182
 183 What:           /sys/kernel/slab/cache/deactivate_to_tail
 184 Date:           February 2008
 185 KernelVersion:  2.6.25
 186 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 187                 Christoph Lameter <cl@linux-foundation.org>
 188 Description:
 189                 The deactivate_to_tail file shows how many times a partial cpu
 190                 slab was deactivated and added to the tail of its node's partial
 191                 list.  It can be written to clear the current count.
 192                 Available when CONFIG_SLUB_STATS is enabled.
 193
 194 What:           /sys/kernel/slab/cache/destroy_by_rcu
 195 Date:           May 2007
 196 KernelVersion:  2.6.22
 197 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 198                 Christoph Lameter <cl@linux-foundation.org>
 199 Description:
 200                 The destroy_by_rcu file is read-only and specifies whether
 201                 slabs (not objects) are freed by rcu.
 202
 203 What:           /sys/kernel/slab/cache/free_add_partial
 204 Date:           February 2008
 205 KernelVersion:  2.6.25
 206 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 207                 Christoph Lameter <cl@linux-foundation.org>
 208 Description:
 209                 The free_add_partial file shows how many times an object has
 210                 been freed in a full slab so that it had to added to its node's
 211                 partial list.  It can be written to clear the current count.
 212                 Available when CONFIG_SLUB_STATS is enabled.
 213
 214 What:           /sys/kernel/slab/cache/free_calls
 215 Date:           May 2007
 216 KernelVersion:  2.6.22
 217 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 218                 Christoph Lameter <cl@linux-foundation.org>
 219 Description:
 220                 The free_calls file is read-only and lists the locations of
 221                 object frees if slab debugging is enabled (see
 222                 Documentation/vm/slub.txt).
 223
 224 What:           /sys/kernel/slab/cache/free_fastpath
 225 Date:           February 2008
 226 KernelVersion:  2.6.25
 227 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 228                 Christoph Lameter <cl@linux-foundation.org>
 229 Description:
 230                 The free_fastpath file shows how many objects have been freed
 231                 using the fast path because it was an object from the cpu slab.
 232                 It can be written to clear the current count.
 233                 Available when CONFIG_SLUB_STATS is enabled.
 234
 235 What:           /sys/kernel/slab/cache/free_frozen
 236 Date:           February 2008
 237 KernelVersion:  2.6.25
 238 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 239                 Christoph Lameter <cl@linux-foundation.org>
 240 Description:
 241                 The free_frozen file shows how many objects have been freed to
 242                 a frozen slab (i.e. a remote cpu slab).  It can be written to
 243                 clear the current count.
 244                 Available when CONFIG_SLUB_STATS is enabled.
 245
 246 What:           /sys/kernel/slab/cache/free_remove_partial
 247 Date:           February 2008
 248 KernelVersion:  2.6.25
 249 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 250                 Christoph Lameter <cl@linux-foundation.org>
 251 Description:
 252                 The free_remove_partial file shows how many times an object has
 253                 been freed to a now-empty slab so that it had to be removed from
 254                 its node's partial list.  It can be written to clear the current
 255                 count.
 256                 Available when CONFIG_SLUB_STATS is enabled.
 257
 258 What:           /sys/kernel/slab/cache/free_slab
 259 Date:           February 2008
 260 KernelVersion:  2.6.25
 261 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 262                 Christoph Lameter <cl@linux-foundation.org>
 263 Description:
 264                 The free_slab file shows how many times an empty slab has been
 265                 freed back to the page allocator.  It can be written to clear
 266                 the current count.
 267                 Available when CONFIG_SLUB_STATS is enabled.
 268
 269 What:           /sys/kernel/slab/cache/free_slowpath
 270 Date:           February 2008
 271 KernelVersion:  2.6.25
 272 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 273                 Christoph Lameter <cl@linux-foundation.org>
 274 Description:
 275                 The free_slowpath file shows how many objects have been freed
 276                 using the slow path (i.e. to a full or partial slab).  It can
 277                 be written to clear the current count.
 278                 Available when CONFIG_SLUB_STATS is enabled.
 279
 280 What:           /sys/kernel/slab/cache/hwcache_align
 281 Date:           May 2007
 282 KernelVersion:  2.6.22
 283 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 284                 Christoph Lameter <cl@linux-foundation.org>
 285 Description:
 286                 The hwcache_align file is read-only and specifies whether
 287                 objects are aligned on cachelines.
 288
 289 What:           /sys/kernel/slab/cache/min_partial
 290 Date:           February 2009
 291 KernelVersion:  2.6.30
 292 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 293                 David Rientjes <rientjes@google.com>
 294 Description:
 295                 The min_partial file specifies how many empty slabs shall
 296                 remain on a node's partial list to avoid the overhead of
 297                 allocating new slabs.  Such slabs may be reclaimed by utilizing
 298                 the shrink file.
 299
 300 What:           /sys/kernel/slab/cache/object_size
 301 Date:           May 2007
 302 KernelVersion:  2.6.22
 303 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 304                 Christoph Lameter <cl@linux-foundation.org>
 305 Description:
 306                 The object_size file is read-only and specifies the cache's
 307                 object size.
 308
 309 What:           /sys/kernel/slab/cache/objects
 310 Date:           May 2007
 311 KernelVersion:  2.6.22
 312 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 313                 Christoph Lameter <cl@linux-foundation.org>
 314 Description:
 315                 The objects file is read-only and displays how many objects are
 316                 active and from which nodes they are from.
 317
 318 What:           /sys/kernel/slab/cache/objects_partial
 319 Date:           April 2008
 320 KernelVersion:  2.6.26
 321 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 322                 Christoph Lameter <cl@linux-foundation.org>
 323 Description:
 324                 The objects_partial file is read-only and displays how many
 325                 objects are on partial slabs and from which nodes they are
 326                 from.
 327
 328 What:           /sys/kernel/slab/cache/objs_per_slab
 329 Date:           May 2007
 330 KernelVersion:  2.6.22
 331 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 332                 Christoph Lameter <cl@linux-foundation.org>
 333 Description:
 334                 The file objs_per_slab is read-only and specifies how many
 335                 objects may be allocated from a single slab of the order
 336                 specified in /sys/kernel/slab/cache/order.
 337
 338 What:           /sys/kernel/slab/cache/order
 339 Date:           May 2007
 340 KernelVersion:  2.6.22
 341 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 342                 Christoph Lameter <cl@linux-foundation.org>
 343 Description:
 344                 The order file specifies the page order at which new slabs are
 345                 allocated.  It is writable and can be changed to increase the
 346                 number of objects per slab.  If a slab cannot be allocated
 347                 because of fragmentation, SLUB will retry with the minimum order
 348                 possible depending on its characteristics.
 349                 When debug_guardpage_minorder=N (N > 0) parameter is specified
 350                 (see Documentation/admin-guide/kernel-parameters.rst), the minimum possible
 351                 order is used and this sysfs entry can not be used to change
 352                 the order at run time.
 353
 354 What:           /sys/kernel/slab/cache/order_fallback
 355 Date:           April 2008
 356 KernelVersion:  2.6.26
 357 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 358                 Christoph Lameter <cl@linux-foundation.org>
 359 Description:
 360                 The order_fallback file shows how many times an allocation of a
 361                 new slab has not been possible at the cache's order and instead
 362                 fallen back to its minimum possible order.  It can be written to
 363                 clear the current count.
 364                 Available when CONFIG_SLUB_STATS is enabled.
 365
 366 What:           /sys/kernel/slab/cache/partial
 367 Date:           May 2007
 368 KernelVersion:  2.6.22
 369 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 370                 Christoph Lameter <cl@linux-foundation.org>
 371 Description:
 372                 The partial file is read-only and displays how long many
 373                 partial slabs there are and how long each node's list is.
 374
 375 What:           /sys/kernel/slab/cache/poison
 376 Date:           May 2007
 377 KernelVersion:  2.6.22
 378 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 379                 Christoph Lameter <cl@linux-foundation.org>
 380 Description:
 381                 The poison file specifies whether objects should be poisoned
 382                 when a new slab is allocated.
 383
 384 What:           /sys/kernel/slab/cache/reclaim_account
 385 Date:           May 2007
 386 KernelVersion:  2.6.22
 387 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 388                 Christoph Lameter <cl@linux-foundation.org>
 389 Description:
 390                 The reclaim_account file specifies whether the cache's objects
 391                 are reclaimable (and grouped by their mobility).
 392
 393 What:           /sys/kernel/slab/cache/red_zone
 394 Date:           May 2007
 395 KernelVersion:  2.6.22
 396 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 397                 Christoph Lameter <cl@linux-foundation.org>
 398 Description:
 399                 The red_zone file specifies whether the cache's objects are red
 400                 zoned.
 401
 402 What:           /sys/kernel/slab/cache/remote_node_defrag_ratio
 403 Date:           January 2008
 404 KernelVersion:  2.6.25
 405 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 406                 Christoph Lameter <cl@linux-foundation.org>
 407 Description:
 408                 The file remote_node_defrag_ratio specifies the percentage of
 409                 times SLUB will attempt to refill the cpu slab with a partial
 410                 slab from a remote node as opposed to allocating a new slab on
 411                 the local node.  This reduces the amount of wasted memory over
 412                 the entire system but can be expensive.
 413                 Available when CONFIG_NUMA is enabled.
 414
 415 What:           /sys/kernel/slab/cache/sanity_checks
 416 Date:           May 2007
 417 KernelVersion:  2.6.22
 418 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 419                 Christoph Lameter <cl@linux-foundation.org>
 420 Description:
 421                 The sanity_checks file specifies whether expensive checks
 422                 should be performed on free and, at minimum, enables double free
 423                 checks.  Caches that enable sanity_checks cannot be merged with
 424                 caches that do not.
 425
 426 What:           /sys/kernel/slab/cache/shrink
 427 Date:           May 2007
 428 KernelVersion:  2.6.22
 429 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 430                 Christoph Lameter <cl@linux-foundation.org>
 431 Description:
 432                 The shrink file is written when memory should be reclaimed from
 433                 a cache.  Empty partial slabs are freed and the partial list is
 434                 sorted so the slabs with the fewest available objects are used
 435                 first.
 436
 437 What:           /sys/kernel/slab/cache/slab_size
 438 Date:           May 2007
 439 KernelVersion:  2.6.22
 440 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 441                 Christoph Lameter <cl@linux-foundation.org>
 442 Description:
 443                 The slab_size file is read-only and specifies the object size
 444                 with metadata (debugging information and alignment) in bytes.
 445
 446 What:           /sys/kernel/slab/cache/slabs
 447 Date:           May 2007
 448 KernelVersion:  2.6.22
 449 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 450                 Christoph Lameter <cl@linux-foundation.org>
 451 Description:
 452                 The slabs file is read-only and displays how long many slabs
 453                 there are (both cpu and partial) and from which nodes they are
 454                 from.
 455
 456 What:           /sys/kernel/slab/cache/store_user
 457 Date:           May 2007
 458 KernelVersion:  2.6.22
 459 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 460                 Christoph Lameter <cl@linux-foundation.org>
 461 Description:
 462                 The store_user file specifies whether the location of
 463                 allocation or free should be tracked for a cache.
 464
 465 What:           /sys/kernel/slab/cache/total_objects
 466 Date:           April 2008
 467 KernelVersion:  2.6.26
 468 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 469                 Christoph Lameter <cl@linux-foundation.org>
 470 Description:
 471                 The total_objects file is read-only and displays how many total
 472                 objects a cache has and from which nodes they are from.
 473
 474 What:           /sys/kernel/slab/cache/trace
 475 Date:           May 2007
 476 KernelVersion:  2.6.22
 477 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 478                 Christoph Lameter <cl@linux-foundation.org>
 479 Description:
 480                 The trace file specifies whether object allocations and frees
 481                 should be traced.
 482
 483 What:           /sys/kernel/slab/cache/validate
 484 Date:           May 2007
 485 KernelVersion:  2.6.22
 486 Contact:        Pekka Enberg <penberg@cs.helsinki.fi>,
 487                 Christoph Lameter <cl@linux-foundation.org>
 488 Description:
 489                 Writing to the validate file causes SLUB to traverse all of its
 490                 cache's objects and check the validity of metadata.