2 * Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
3 * Copyright (C) 2007 The Regents of the University of California.
4 * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
5 * Written by Brian Behlendorf <behlendorf1@llnl.gov>.
8 * This file is part of the SPL, Solaris Porting Layer.
9 * For details, see <http://zfsonlinux.org/>.
11 * The SPL is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by the
13 * Free Software Foundation; either version 2 of the License, or (at your
14 * option) any later version.
16 * The SPL is distributed in the hope that it will be useful, but WITHOUT
17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
21 * You should have received a copy of the GNU General Public License along
22 * with the SPL. If not, see <http://www.gnu.org/licenses/>.
26 #include <sys/kmem_cache.h>
27 #include <sys/taskq.h>
28 #include <sys/timer.h>
30 #include <linux/slab.h>
31 #include <linux/swap.h>
32 #include <linux/mm_compat.h>
33 #include <linux/wait_compat.h>
34 #include <linux/prefetch.h>
37 * Within the scope of spl-kmem.c file the kmem_cache_* definitions
38 * are removed to allow access to the real Linux slab allocator.
40 #undef kmem_cache_destroy
41 #undef kmem_cache_create
42 #undef kmem_cache_alloc
43 #undef kmem_cache_free
47 * Linux 3.16 replaced smp_mb__{before,after}_{atomic,clear}_{dec,inc,bit}()
48 * with smp_mb__{before,after}_atomic() because they were redundant. This is
49 * only used inside our SLAB allocator, so we implement an internal wrapper
50 * here to give us smp_mb__{before,after}_atomic() on older kernels.
52 #ifndef smp_mb__before_atomic
53 #define smp_mb__before_atomic(x) smp_mb__before_clear_bit(x)
56 #ifndef smp_mb__after_atomic
57 #define smp_mb__after_atomic(x) smp_mb__after_clear_bit(x)
61 * Cache expiration was implemented because it was part of the default Solaris
62 * kmem_cache behavior. The idea is that per-cpu objects which haven't been
63 * accessed in several seconds should be returned to the cache. On the other
64 * hand Linux slabs never move objects back to the slabs unless there is
65 * memory pressure on the system. By default the Linux method is enabled
66 * because it has been shown to improve responsiveness on low memory systems.
67 * This policy may be changed by setting KMC_EXPIRE_AGE or KMC_EXPIRE_MEM.
69 unsigned int spl_kmem_cache_expire
= KMC_EXPIRE_MEM
;
70 EXPORT_SYMBOL(spl_kmem_cache_expire
);
71 module_param(spl_kmem_cache_expire
, uint
, 0644);
72 MODULE_PARM_DESC(spl_kmem_cache_expire
, "By age (0x1) or low memory (0x2)");
75 * Cache magazines are an optimization designed to minimize the cost of
76 * allocating memory. They do this by keeping a per-cpu cache of recently
77 * freed objects, which can then be reallocated without taking a lock. This
78 * can improve performance on highly contended caches. However, because
79 * objects in magazines will prevent otherwise empty slabs from being
80 * immediately released this may not be ideal for low memory machines.
82 * For this reason spl_kmem_cache_magazine_size can be used to set a maximum
83 * magazine size. When this value is set to 0 the magazine size will be
84 * automatically determined based on the object size. Otherwise magazines
85 * will be limited to 2-256 objects per magazine (i.e per cpu). Magazines
86 * may never be entirely disabled in this implementation.
88 unsigned int spl_kmem_cache_magazine_size
= 0;
89 module_param(spl_kmem_cache_magazine_size
, uint
, 0444);
90 MODULE_PARM_DESC(spl_kmem_cache_magazine_size
,
91 "Default magazine size (2-256), set automatically (0)\n");
94 * The default behavior is to report the number of objects remaining in the
95 * cache. This allows the Linux VM to repeatedly reclaim objects from the
96 * cache when memory is low satisfy other memory allocations. Alternately,
97 * setting this value to KMC_RECLAIM_ONCE limits how aggressively the cache
98 * is reclaimed. This may increase the likelihood of out of memory events.
100 unsigned int spl_kmem_cache_reclaim
= 0 /* KMC_RECLAIM_ONCE */;
101 module_param(spl_kmem_cache_reclaim
, uint
, 0644);
102 MODULE_PARM_DESC(spl_kmem_cache_reclaim
, "Single reclaim pass (0x1)");
104 unsigned int spl_kmem_cache_obj_per_slab
= SPL_KMEM_CACHE_OBJ_PER_SLAB
;
105 module_param(spl_kmem_cache_obj_per_slab
, uint
, 0644);
106 MODULE_PARM_DESC(spl_kmem_cache_obj_per_slab
, "Number of objects per slab");
108 unsigned int spl_kmem_cache_obj_per_slab_min
= SPL_KMEM_CACHE_OBJ_PER_SLAB_MIN
;
109 module_param(spl_kmem_cache_obj_per_slab_min
, uint
, 0644);
110 MODULE_PARM_DESC(spl_kmem_cache_obj_per_slab_min
,
111 "Minimal number of objects per slab");
113 unsigned int spl_kmem_cache_max_size
= SPL_KMEM_CACHE_MAX_SIZE
;
114 module_param(spl_kmem_cache_max_size
, uint
, 0644);
115 MODULE_PARM_DESC(spl_kmem_cache_max_size
, "Maximum size of slab in MB");
118 * For small objects the Linux slab allocator should be used to make the most
119 * efficient use of the memory. However, large objects are not supported by
120 * the Linux slab and therefore the SPL implementation is preferred. A cutoff
121 * of 16K was determined to be optimal for architectures using 4K pages.
123 #if PAGE_SIZE == 4096
124 unsigned int spl_kmem_cache_slab_limit
= 16384;
126 unsigned int spl_kmem_cache_slab_limit
= 0;
128 module_param(spl_kmem_cache_slab_limit
, uint
, 0644);
129 MODULE_PARM_DESC(spl_kmem_cache_slab_limit
,
130 "Objects less than N bytes use the Linux slab");
133 * This value defaults to a threshold designed to avoid allocations which
134 * have been deemed costly by the kernel.
136 unsigned int spl_kmem_cache_kmem_limit
=
137 ((1 << (PAGE_ALLOC_COSTLY_ORDER
- 1)) * PAGE_SIZE
) /
138 SPL_KMEM_CACHE_OBJ_PER_SLAB
;
139 module_param(spl_kmem_cache_kmem_limit
, uint
, 0644);
140 MODULE_PARM_DESC(spl_kmem_cache_kmem_limit
,
141 "Objects less than N bytes use the kmalloc");
144 * The number of threads available to allocate new slabs for caches. This
145 * should not need to be tuned but it is available for performance analysis.
147 unsigned int spl_kmem_cache_kmem_threads
= 4;
148 module_param(spl_kmem_cache_kmem_threads
, uint
, 0444);
149 MODULE_PARM_DESC(spl_kmem_cache_kmem_threads
,
150 "Number of spl_kmem_cache threads");
153 * Slab allocation interfaces
155 * While the Linux slab implementation was inspired by the Solaris
156 * implementation I cannot use it to emulate the Solaris APIs. I
157 * require two features which are not provided by the Linux slab.
159 * 1) Constructors AND destructors. Recent versions of the Linux
160 * kernel have removed support for destructors. This is a deal
161 * breaker for the SPL which contains particularly expensive
162 * initializers for mutex's, condition variables, etc. We also
163 * require a minimal level of cleanup for these data types unlike
164 * many Linux data types which do need to be explicitly destroyed.
166 * 2) Virtual address space backed slab. Callers of the Solaris slab
167 * expect it to work well for both small are very large allocations.
168 * Because of memory fragmentation the Linux slab which is backed
169 * by kmalloc'ed memory performs very badly when confronted with
170 * large numbers of large allocations. Basing the slab on the
171 * virtual address space removes the need for contiguous pages
172 * and greatly improve performance for large allocations.
174 * For these reasons, the SPL has its own slab implementation with
175 * the needed features. It is not as highly optimized as either the
176 * Solaris or Linux slabs, but it should get me most of what is
177 * needed until it can be optimized or obsoleted by another approach.
179 * One serious concern I do have about this method is the relatively
180 * small virtual address space on 32bit arches. This will seriously
181 * constrain the size of the slab caches and their performance.
184 struct list_head spl_kmem_cache_list
; /* List of caches */
185 struct rw_semaphore spl_kmem_cache_sem
; /* Cache list lock */
186 taskq_t
*spl_kmem_cache_taskq
; /* Task queue for ageing / reclaim */
188 static void spl_cache_shrink(spl_kmem_cache_t
*skc
, void *obj
);
190 SPL_SHRINKER_CALLBACK_FWD_DECLARE(spl_kmem_cache_generic_shrinker
);
191 SPL_SHRINKER_DECLARE(spl_kmem_cache_shrinker
,
192 spl_kmem_cache_generic_shrinker
, KMC_DEFAULT_SEEKS
);
195 kv_alloc(spl_kmem_cache_t
*skc
, int size
, int flags
)
197 gfp_t lflags
= kmem_flags_convert(flags
);
200 if (skc
->skc_flags
& KMC_KMEM
) {
202 ptr
= (void *)__get_free_pages(lflags
, get_order(size
));
204 ptr
= __vmalloc(size
, lflags
| __GFP_HIGHMEM
, PAGE_KERNEL
);
207 /* Resulting allocated memory will be page aligned */
208 ASSERT(IS_P2ALIGNED(ptr
, PAGE_SIZE
));
214 kv_free(spl_kmem_cache_t
*skc
, void *ptr
, int size
)
216 ASSERT(IS_P2ALIGNED(ptr
, PAGE_SIZE
));
219 * The Linux direct reclaim path uses this out of band value to
220 * determine if forward progress is being made. Normally this is
221 * incremented by kmem_freepages() which is part of the various
222 * Linux slab implementations. However, since we are using none
223 * of that infrastructure we are responsible for incrementing it.
225 if (current
->reclaim_state
)
226 current
->reclaim_state
->reclaimed_slab
+= size
>> PAGE_SHIFT
;
228 if (skc
->skc_flags
& KMC_KMEM
) {
230 free_pages((unsigned long)ptr
, get_order(size
));
237 * Required space for each aligned sks.
239 static inline uint32_t
240 spl_sks_size(spl_kmem_cache_t
*skc
)
242 return (P2ROUNDUP_TYPED(sizeof (spl_kmem_slab_t
),
243 skc
->skc_obj_align
, uint32_t));
247 * Required space for each aligned object.
249 static inline uint32_t
250 spl_obj_size(spl_kmem_cache_t
*skc
)
252 uint32_t align
= skc
->skc_obj_align
;
254 return (P2ROUNDUP_TYPED(skc
->skc_obj_size
, align
, uint32_t) +
255 P2ROUNDUP_TYPED(sizeof (spl_kmem_obj_t
), align
, uint32_t));
259 * Lookup the spl_kmem_object_t for an object given that object.
261 static inline spl_kmem_obj_t
*
262 spl_sko_from_obj(spl_kmem_cache_t
*skc
, void *obj
)
264 return (obj
+ P2ROUNDUP_TYPED(skc
->skc_obj_size
,
265 skc
->skc_obj_align
, uint32_t));
269 * Required space for each offslab object taking in to account alignment
270 * restrictions and the power-of-two requirement of kv_alloc().
272 static inline uint32_t
273 spl_offslab_size(spl_kmem_cache_t
*skc
)
275 return (1UL << (fls64(spl_obj_size(skc
)) + 1));
279 * It's important that we pack the spl_kmem_obj_t structure and the
280 * actual objects in to one large address space to minimize the number
281 * of calls to the allocator. It is far better to do a few large
282 * allocations and then subdivide it ourselves. Now which allocator
283 * we use requires balancing a few trade offs.
285 * For small objects we use kmem_alloc() because as long as you are
286 * only requesting a small number of pages (ideally just one) its cheap.
287 * However, when you start requesting multiple pages with kmem_alloc()
288 * it gets increasingly expensive since it requires contiguous pages.
289 * For this reason we shift to vmem_alloc() for slabs of large objects
290 * which removes the need for contiguous pages. We do not use
291 * vmem_alloc() in all cases because there is significant locking
292 * overhead in __get_vm_area_node(). This function takes a single
293 * global lock when acquiring an available virtual address range which
294 * serializes all vmem_alloc()'s for all slab caches. Using slightly
295 * different allocation functions for small and large objects should
296 * give us the best of both worlds.
298 * KMC_ONSLAB KMC_OFFSLAB
300 * +------------------------+ +-----------------+
301 * | spl_kmem_slab_t --+-+ | | spl_kmem_slab_t |---+-+
302 * | skc_obj_size <-+ | | +-----------------+ | |
303 * | spl_kmem_obj_t | | | |
304 * | skc_obj_size <---+ | +-----------------+ | |
305 * | spl_kmem_obj_t | | | skc_obj_size | <-+ |
306 * | ... v | | spl_kmem_obj_t | |
307 * +------------------------+ +-----------------+ v
309 static spl_kmem_slab_t
*
310 spl_slab_alloc(spl_kmem_cache_t
*skc
, int flags
)
312 spl_kmem_slab_t
*sks
;
313 spl_kmem_obj_t
*sko
, *n
;
315 uint32_t obj_size
, offslab_size
= 0;
318 base
= kv_alloc(skc
, skc
->skc_slab_size
, flags
);
322 sks
= (spl_kmem_slab_t
*)base
;
323 sks
->sks_magic
= SKS_MAGIC
;
324 sks
->sks_objs
= skc
->skc_slab_objs
;
325 sks
->sks_age
= jiffies
;
326 sks
->sks_cache
= skc
;
327 INIT_LIST_HEAD(&sks
->sks_list
);
328 INIT_LIST_HEAD(&sks
->sks_free_list
);
330 obj_size
= spl_obj_size(skc
);
332 if (skc
->skc_flags
& KMC_OFFSLAB
)
333 offslab_size
= spl_offslab_size(skc
);
335 for (i
= 0; i
< sks
->sks_objs
; i
++) {
336 if (skc
->skc_flags
& KMC_OFFSLAB
) {
337 obj
= kv_alloc(skc
, offslab_size
, flags
);
343 obj
= base
+ spl_sks_size(skc
) + (i
* obj_size
);
346 ASSERT(IS_P2ALIGNED(obj
, skc
->skc_obj_align
));
347 sko
= spl_sko_from_obj(skc
, obj
);
349 sko
->sko_magic
= SKO_MAGIC
;
351 INIT_LIST_HEAD(&sko
->sko_list
);
352 list_add_tail(&sko
->sko_list
, &sks
->sks_free_list
);
357 if (skc
->skc_flags
& KMC_OFFSLAB
)
358 list_for_each_entry_safe(sko
,
359 n
, &sks
->sks_free_list
, sko_list
)
360 kv_free(skc
, sko
->sko_addr
, offslab_size
);
362 kv_free(skc
, base
, skc
->skc_slab_size
);
370 * Remove a slab from complete or partial list, it must be called with
371 * the 'skc->skc_lock' held but the actual free must be performed
372 * outside the lock to prevent deadlocking on vmem addresses.
375 spl_slab_free(spl_kmem_slab_t
*sks
,
376 struct list_head
*sks_list
, struct list_head
*sko_list
)
378 spl_kmem_cache_t
*skc
;
380 ASSERT(sks
->sks_magic
== SKS_MAGIC
);
381 ASSERT(sks
->sks_ref
== 0);
383 skc
= sks
->sks_cache
;
384 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
385 ASSERT(spin_is_locked(&skc
->skc_lock
));
388 * Update slab/objects counters in the cache, then remove the
389 * slab from the skc->skc_partial_list. Finally add the slab
390 * and all its objects in to the private work lists where the
391 * destructors will be called and the memory freed to the system.
393 skc
->skc_obj_total
-= sks
->sks_objs
;
394 skc
->skc_slab_total
--;
395 list_del(&sks
->sks_list
);
396 list_add(&sks
->sks_list
, sks_list
);
397 list_splice_init(&sks
->sks_free_list
, sko_list
);
401 * Reclaim empty slabs at the end of the partial list.
404 spl_slab_reclaim(spl_kmem_cache_t
*skc
)
406 spl_kmem_slab_t
*sks
, *m
;
407 spl_kmem_obj_t
*sko
, *n
;
413 * Empty slabs and objects must be moved to a private list so they
414 * can be safely freed outside the spin lock. All empty slabs are
415 * at the end of skc->skc_partial_list, therefore once a non-empty
416 * slab is found we can stop scanning.
418 spin_lock(&skc
->skc_lock
);
419 list_for_each_entry_safe_reverse(sks
, m
,
420 &skc
->skc_partial_list
, sks_list
) {
422 if (sks
->sks_ref
> 0)
425 spl_slab_free(sks
, &sks_list
, &sko_list
);
427 spin_unlock(&skc
->skc_lock
);
430 * The following two loops ensure all the object destructors are
431 * run, any offslab objects are freed, and the slabs themselves
432 * are freed. This is all done outside the skc->skc_lock since
433 * this allows the destructor to sleep, and allows us to perform
434 * a conditional reschedule when a freeing a large number of
435 * objects and slabs back to the system.
437 if (skc
->skc_flags
& KMC_OFFSLAB
)
438 size
= spl_offslab_size(skc
);
440 list_for_each_entry_safe(sko
, n
, &sko_list
, sko_list
) {
441 ASSERT(sko
->sko_magic
== SKO_MAGIC
);
443 if (skc
->skc_flags
& KMC_OFFSLAB
)
444 kv_free(skc
, sko
->sko_addr
, size
);
447 list_for_each_entry_safe(sks
, m
, &sks_list
, sks_list
) {
448 ASSERT(sks
->sks_magic
== SKS_MAGIC
);
449 kv_free(skc
, sks
, skc
->skc_slab_size
);
453 static spl_kmem_emergency_t
*
454 spl_emergency_search(struct rb_root
*root
, void *obj
)
456 struct rb_node
*node
= root
->rb_node
;
457 spl_kmem_emergency_t
*ske
;
458 unsigned long address
= (unsigned long)obj
;
461 ske
= container_of(node
, spl_kmem_emergency_t
, ske_node
);
463 if (address
< ske
->ske_obj
)
464 node
= node
->rb_left
;
465 else if (address
> ske
->ske_obj
)
466 node
= node
->rb_right
;
475 spl_emergency_insert(struct rb_root
*root
, spl_kmem_emergency_t
*ske
)
477 struct rb_node
**new = &(root
->rb_node
), *parent
= NULL
;
478 spl_kmem_emergency_t
*ske_tmp
;
479 unsigned long address
= ske
->ske_obj
;
482 ske_tmp
= container_of(*new, spl_kmem_emergency_t
, ske_node
);
485 if (address
< ske_tmp
->ske_obj
)
486 new = &((*new)->rb_left
);
487 else if (address
> ske_tmp
->ske_obj
)
488 new = &((*new)->rb_right
);
493 rb_link_node(&ske
->ske_node
, parent
, new);
494 rb_insert_color(&ske
->ske_node
, root
);
500 * Allocate a single emergency object and track it in a red black tree.
503 spl_emergency_alloc(spl_kmem_cache_t
*skc
, int flags
, void **obj
)
505 gfp_t lflags
= kmem_flags_convert(flags
);
506 spl_kmem_emergency_t
*ske
;
507 int order
= get_order(skc
->skc_obj_size
);
510 /* Last chance use a partial slab if one now exists */
511 spin_lock(&skc
->skc_lock
);
512 empty
= list_empty(&skc
->skc_partial_list
);
513 spin_unlock(&skc
->skc_lock
);
517 ske
= kmalloc(sizeof (*ske
), lflags
);
521 ske
->ske_obj
= __get_free_pages(lflags
, order
);
522 if (ske
->ske_obj
== 0) {
527 spin_lock(&skc
->skc_lock
);
528 empty
= spl_emergency_insert(&skc
->skc_emergency_tree
, ske
);
530 skc
->skc_obj_total
++;
531 skc
->skc_obj_emergency
++;
532 if (skc
->skc_obj_emergency
> skc
->skc_obj_emergency_max
)
533 skc
->skc_obj_emergency_max
= skc
->skc_obj_emergency
;
535 spin_unlock(&skc
->skc_lock
);
537 if (unlikely(!empty
)) {
538 free_pages(ske
->ske_obj
, order
);
543 *obj
= (void *)ske
->ske_obj
;
549 * Locate the passed object in the red black tree and free it.
552 spl_emergency_free(spl_kmem_cache_t
*skc
, void *obj
)
554 spl_kmem_emergency_t
*ske
;
555 int order
= get_order(skc
->skc_obj_size
);
557 spin_lock(&skc
->skc_lock
);
558 ske
= spl_emergency_search(&skc
->skc_emergency_tree
, obj
);
560 rb_erase(&ske
->ske_node
, &skc
->skc_emergency_tree
);
561 skc
->skc_obj_emergency
--;
562 skc
->skc_obj_total
--;
564 spin_unlock(&skc
->skc_lock
);
569 free_pages(ske
->ske_obj
, order
);
576 * Release objects from the per-cpu magazine back to their slab. The flush
577 * argument contains the max number of entries to remove from the magazine.
580 __spl_cache_flush(spl_kmem_cache_t
*skc
, spl_kmem_magazine_t
*skm
, int flush
)
582 int i
, count
= MIN(flush
, skm
->skm_avail
);
584 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
585 ASSERT(skm
->skm_magic
== SKM_MAGIC
);
586 ASSERT(spin_is_locked(&skc
->skc_lock
));
588 for (i
= 0; i
< count
; i
++)
589 spl_cache_shrink(skc
, skm
->skm_objs
[i
]);
591 skm
->skm_avail
-= count
;
592 memmove(skm
->skm_objs
, &(skm
->skm_objs
[count
]),
593 sizeof (void *) * skm
->skm_avail
);
597 spl_cache_flush(spl_kmem_cache_t
*skc
, spl_kmem_magazine_t
*skm
, int flush
)
599 spin_lock(&skc
->skc_lock
);
600 __spl_cache_flush(skc
, skm
, flush
);
601 spin_unlock(&skc
->skc_lock
);
605 spl_magazine_age(void *data
)
607 spl_kmem_cache_t
*skc
= (spl_kmem_cache_t
*)data
;
608 spl_kmem_magazine_t
*skm
= skc
->skc_mag
[smp_processor_id()];
610 ASSERT(skm
->skm_magic
== SKM_MAGIC
);
611 ASSERT(skm
->skm_cpu
== smp_processor_id());
612 ASSERT(irqs_disabled());
614 /* There are no available objects or they are too young to age out */
615 if ((skm
->skm_avail
== 0) ||
616 time_before(jiffies
, skm
->skm_age
+ skc
->skc_delay
* HZ
))
620 * Because we're executing in interrupt context we may have
621 * interrupted the holder of this lock. To avoid a potential
622 * deadlock return if the lock is contended.
624 if (!spin_trylock(&skc
->skc_lock
))
627 __spl_cache_flush(skc
, skm
, skm
->skm_refill
);
628 spin_unlock(&skc
->skc_lock
);
632 * Called regularly to keep a downward pressure on the cache.
634 * Objects older than skc->skc_delay seconds in the per-cpu magazines will
635 * be returned to the caches. This is done to prevent idle magazines from
636 * holding memory which could be better used elsewhere. The delay is
637 * present to prevent thrashing the magazine.
639 * The newly released objects may result in empty partial slabs. Those
640 * slabs should be released to the system. Otherwise moving the objects
641 * out of the magazines is just wasted work.
644 spl_cache_age(void *data
)
646 spl_kmem_cache_t
*skc
= (spl_kmem_cache_t
*)data
;
649 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
651 /* Dynamically disabled at run time */
652 if (!(spl_kmem_cache_expire
& KMC_EXPIRE_AGE
))
655 atomic_inc(&skc
->skc_ref
);
657 if (!(skc
->skc_flags
& KMC_NOMAGAZINE
))
658 on_each_cpu(spl_magazine_age
, skc
, 1);
660 spl_slab_reclaim(skc
);
662 while (!test_bit(KMC_BIT_DESTROY
, &skc
->skc_flags
) && !id
) {
663 id
= taskq_dispatch_delay(
664 spl_kmem_cache_taskq
, spl_cache_age
, skc
, TQ_SLEEP
,
665 ddi_get_lbolt() + skc
->skc_delay
/ 3 * HZ
);
667 /* Destroy issued after dispatch immediately cancel it */
668 if (test_bit(KMC_BIT_DESTROY
, &skc
->skc_flags
) && id
)
669 taskq_cancel_id(spl_kmem_cache_taskq
, id
);
672 spin_lock(&skc
->skc_lock
);
673 skc
->skc_taskqid
= id
;
674 spin_unlock(&skc
->skc_lock
);
676 atomic_dec(&skc
->skc_ref
);
680 * Size a slab based on the size of each aligned object plus spl_kmem_obj_t.
681 * When on-slab we want to target spl_kmem_cache_obj_per_slab. However,
682 * for very small objects we may end up with more than this so as not
683 * to waste space in the minimal allocation of a single page. Also for
684 * very large objects we may use as few as spl_kmem_cache_obj_per_slab_min,
685 * lower than this and we will fail.
688 spl_slab_size(spl_kmem_cache_t
*skc
, uint32_t *objs
, uint32_t *size
)
690 uint32_t sks_size
, obj_size
, max_size
, tgt_size
, tgt_objs
;
692 if (skc
->skc_flags
& KMC_OFFSLAB
) {
693 tgt_objs
= spl_kmem_cache_obj_per_slab
;
694 tgt_size
= P2ROUNDUP(sizeof (spl_kmem_slab_t
), PAGE_SIZE
);
696 if ((skc
->skc_flags
& KMC_KMEM
) &&
697 (spl_obj_size(skc
) > (SPL_MAX_ORDER_NR_PAGES
* PAGE_SIZE
)))
700 sks_size
= spl_sks_size(skc
);
701 obj_size
= spl_obj_size(skc
);
702 max_size
= (spl_kmem_cache_max_size
* 1024 * 1024);
703 tgt_size
= (spl_kmem_cache_obj_per_slab
* obj_size
+ sks_size
);
706 * KMC_KMEM slabs are allocated by __get_free_pages() which
707 * rounds up to the nearest order. Knowing this the size
708 * should be rounded up to the next power of two with a hard
709 * maximum defined by the maximum allowed allocation order.
711 if (skc
->skc_flags
& KMC_KMEM
) {
712 max_size
= SPL_MAX_ORDER_NR_PAGES
* PAGE_SIZE
;
713 tgt_size
= MIN(max_size
,
714 PAGE_SIZE
* (1 << MAX(get_order(tgt_size
) - 1, 1)));
717 if (tgt_size
<= max_size
) {
718 tgt_objs
= (tgt_size
- sks_size
) / obj_size
;
720 tgt_objs
= (max_size
- sks_size
) / obj_size
;
721 tgt_size
= (tgt_objs
* obj_size
) + sks_size
;
735 * Make a guess at reasonable per-cpu magazine size based on the size of
736 * each object and the cost of caching N of them in each magazine. Long
737 * term this should really adapt based on an observed usage heuristic.
740 spl_magazine_size(spl_kmem_cache_t
*skc
)
742 uint32_t obj_size
= spl_obj_size(skc
);
745 if (spl_kmem_cache_magazine_size
> 0)
746 return (MAX(MIN(spl_kmem_cache_magazine_size
, 256), 2));
748 /* Per-magazine sizes below assume a 4Kib page size */
749 if (obj_size
> (PAGE_SIZE
* 256))
750 size
= 4; /* Minimum 4Mib per-magazine */
751 else if (obj_size
> (PAGE_SIZE
* 32))
752 size
= 16; /* Minimum 2Mib per-magazine */
753 else if (obj_size
> (PAGE_SIZE
))
754 size
= 64; /* Minimum 256Kib per-magazine */
755 else if (obj_size
> (PAGE_SIZE
/ 4))
756 size
= 128; /* Minimum 128Kib per-magazine */
764 * Allocate a per-cpu magazine to associate with a specific core.
766 static spl_kmem_magazine_t
*
767 spl_magazine_alloc(spl_kmem_cache_t
*skc
, int cpu
)
769 spl_kmem_magazine_t
*skm
;
770 int size
= sizeof (spl_kmem_magazine_t
) +
771 sizeof (void *) * skc
->skc_mag_size
;
773 skm
= kmalloc_node(size
, GFP_KERNEL
, cpu_to_node(cpu
));
775 skm
->skm_magic
= SKM_MAGIC
;
777 skm
->skm_size
= skc
->skc_mag_size
;
778 skm
->skm_refill
= skc
->skc_mag_refill
;
779 skm
->skm_cache
= skc
;
780 skm
->skm_age
= jiffies
;
788 * Free a per-cpu magazine associated with a specific core.
791 spl_magazine_free(spl_kmem_magazine_t
*skm
)
793 ASSERT(skm
->skm_magic
== SKM_MAGIC
);
794 ASSERT(skm
->skm_avail
== 0);
799 * Create all pre-cpu magazines of reasonable sizes.
802 spl_magazine_create(spl_kmem_cache_t
*skc
)
806 if (skc
->skc_flags
& KMC_NOMAGAZINE
)
809 skc
->skc_mag
= kzalloc(sizeof (spl_kmem_magazine_t
*) *
810 num_possible_cpus(), kmem_flags_convert(KM_SLEEP
));
811 skc
->skc_mag_size
= spl_magazine_size(skc
);
812 skc
->skc_mag_refill
= (skc
->skc_mag_size
+ 1) / 2;
814 for_each_possible_cpu(i
) {
815 skc
->skc_mag
[i
] = spl_magazine_alloc(skc
, i
);
816 if (!skc
->skc_mag
[i
]) {
817 for (i
--; i
>= 0; i
--)
818 spl_magazine_free(skc
->skc_mag
[i
]);
829 * Destroy all pre-cpu magazines.
832 spl_magazine_destroy(spl_kmem_cache_t
*skc
)
834 spl_kmem_magazine_t
*skm
;
837 if (skc
->skc_flags
& KMC_NOMAGAZINE
)
840 for_each_possible_cpu(i
) {
841 skm
= skc
->skc_mag
[i
];
842 spl_cache_flush(skc
, skm
, skm
->skm_avail
);
843 spl_magazine_free(skm
);
850 * Create a object cache based on the following arguments:
852 * size cache object size
853 * align cache object alignment
854 * ctor cache object constructor
855 * dtor cache object destructor
856 * reclaim cache object reclaim
857 * priv cache private data for ctor/dtor/reclaim
858 * vmp unused must be NULL
860 * KMC_NOTOUCH Disable cache object aging (unsupported)
861 * KMC_NODEBUG Disable debugging (unsupported)
862 * KMC_NOHASH Disable hashing (unsupported)
863 * KMC_QCACHE Disable qcache (unsupported)
864 * KMC_NOMAGAZINE Enabled for kmem/vmem, Disabled for Linux slab
865 * KMC_KMEM Force kmem backed cache
866 * KMC_VMEM Force vmem backed cache
867 * KMC_SLAB Force Linux slab backed cache
868 * KMC_OFFSLAB Locate objects off the slab
871 spl_kmem_cache_create(char *name
, size_t size
, size_t align
,
872 spl_kmem_ctor_t ctor
, spl_kmem_dtor_t dtor
, spl_kmem_reclaim_t reclaim
,
873 void *priv
, void *vmp
, int flags
)
875 gfp_t lflags
= kmem_flags_convert(KM_SLEEP
);
876 spl_kmem_cache_t
*skc
;
882 ASSERT0(flags
& KMC_NOMAGAZINE
);
883 ASSERT0(flags
& KMC_NOHASH
);
884 ASSERT0(flags
& KMC_QCACHE
);
889 skc
= kzalloc(sizeof (*skc
), lflags
);
893 skc
->skc_magic
= SKC_MAGIC
;
894 skc
->skc_name_size
= strlen(name
) + 1;
895 skc
->skc_name
= (char *)kmalloc(skc
->skc_name_size
, lflags
);
896 if (skc
->skc_name
== NULL
) {
900 strncpy(skc
->skc_name
, name
, skc
->skc_name_size
);
902 skc
->skc_ctor
= ctor
;
903 skc
->skc_dtor
= dtor
;
904 skc
->skc_reclaim
= reclaim
;
905 skc
->skc_private
= priv
;
907 skc
->skc_linux_cache
= NULL
;
908 skc
->skc_flags
= flags
;
909 skc
->skc_obj_size
= size
;
910 skc
->skc_obj_align
= SPL_KMEM_CACHE_ALIGN
;
911 skc
->skc_delay
= SPL_KMEM_CACHE_DELAY
;
912 skc
->skc_reap
= SPL_KMEM_CACHE_REAP
;
913 atomic_set(&skc
->skc_ref
, 0);
915 INIT_LIST_HEAD(&skc
->skc_list
);
916 INIT_LIST_HEAD(&skc
->skc_complete_list
);
917 INIT_LIST_HEAD(&skc
->skc_partial_list
);
918 skc
->skc_emergency_tree
= RB_ROOT
;
919 spin_lock_init(&skc
->skc_lock
);
920 init_waitqueue_head(&skc
->skc_waitq
);
921 skc
->skc_slab_fail
= 0;
922 skc
->skc_slab_create
= 0;
923 skc
->skc_slab_destroy
= 0;
924 skc
->skc_slab_total
= 0;
925 skc
->skc_slab_alloc
= 0;
926 skc
->skc_slab_max
= 0;
927 skc
->skc_obj_total
= 0;
928 skc
->skc_obj_alloc
= 0;
929 skc
->skc_obj_max
= 0;
930 skc
->skc_obj_deadlock
= 0;
931 skc
->skc_obj_emergency
= 0;
932 skc
->skc_obj_emergency_max
= 0;
935 * Verify the requested alignment restriction is sane.
939 VERIFY3U(align
, >=, SPL_KMEM_CACHE_ALIGN
);
940 VERIFY3U(align
, <=, PAGE_SIZE
);
941 skc
->skc_obj_align
= align
;
945 * When no specific type of slab is requested (kmem, vmem, or
946 * linuxslab) then select a cache type based on the object size
947 * and default tunables.
949 if (!(skc
->skc_flags
& (KMC_KMEM
| KMC_VMEM
| KMC_SLAB
))) {
952 * Objects smaller than spl_kmem_cache_slab_limit can
953 * use the Linux slab for better space-efficiency. By
954 * default this functionality is disabled until its
955 * performance characteristics are fully understood.
957 if (spl_kmem_cache_slab_limit
&&
958 size
<= (size_t)spl_kmem_cache_slab_limit
)
959 skc
->skc_flags
|= KMC_SLAB
;
962 * Small objects, less than spl_kmem_cache_kmem_limit per
963 * object should use kmem because their slabs are small.
965 else if (spl_obj_size(skc
) <= spl_kmem_cache_kmem_limit
)
966 skc
->skc_flags
|= KMC_KMEM
;
969 * All other objects are considered large and are placed
970 * on vmem backed slabs.
973 skc
->skc_flags
|= KMC_VMEM
;
977 * Given the type of slab allocate the required resources.
979 if (skc
->skc_flags
& (KMC_KMEM
| KMC_VMEM
)) {
980 rc
= spl_slab_size(skc
,
981 &skc
->skc_slab_objs
, &skc
->skc_slab_size
);
985 rc
= spl_magazine_create(skc
);
989 unsigned long slabflags
= 0;
991 if (size
> (SPL_MAX_KMEM_ORDER_NR_PAGES
* PAGE_SIZE
)) {
996 #if defined(SLAB_USERCOPY)
998 * Required for PAX-enabled kernels if the slab is to be
999 * used for coping between user and kernel space.
1001 slabflags
|= SLAB_USERCOPY
;
1004 skc
->skc_linux_cache
= kmem_cache_create(
1005 skc
->skc_name
, size
, align
, slabflags
, NULL
);
1006 if (skc
->skc_linux_cache
== NULL
) {
1011 #if defined(HAVE_KMEM_CACHE_ALLOCFLAGS)
1012 skc
->skc_linux_cache
->allocflags
|= __GFP_COMP
;
1013 #elif defined(HAVE_KMEM_CACHE_GFPFLAGS)
1014 skc
->skc_linux_cache
->gfpflags
|= __GFP_COMP
;
1016 skc
->skc_flags
|= KMC_NOMAGAZINE
;
1019 if (spl_kmem_cache_expire
& KMC_EXPIRE_AGE
)
1020 skc
->skc_taskqid
= taskq_dispatch_delay(spl_kmem_cache_taskq
,
1021 spl_cache_age
, skc
, TQ_SLEEP
,
1022 ddi_get_lbolt() + skc
->skc_delay
/ 3 * HZ
);
1024 down_write(&spl_kmem_cache_sem
);
1025 list_add_tail(&skc
->skc_list
, &spl_kmem_cache_list
);
1026 up_write(&spl_kmem_cache_sem
);
1030 kfree(skc
->skc_name
);
1034 EXPORT_SYMBOL(spl_kmem_cache_create
);
1037 * Register a move callback for cache defragmentation.
1038 * XXX: Unimplemented but harmless to stub out for now.
1041 spl_kmem_cache_set_move(spl_kmem_cache_t
*skc
,
1042 kmem_cbrc_t (move
)(void *, void *, size_t, void *))
1044 ASSERT(move
!= NULL
);
1046 EXPORT_SYMBOL(spl_kmem_cache_set_move
);
1049 * Destroy a cache and all objects associated with the cache.
1052 spl_kmem_cache_destroy(spl_kmem_cache_t
*skc
)
1054 DECLARE_WAIT_QUEUE_HEAD(wq
);
1057 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
1058 ASSERT(skc
->skc_flags
& (KMC_KMEM
| KMC_VMEM
| KMC_SLAB
));
1060 down_write(&spl_kmem_cache_sem
);
1061 list_del_init(&skc
->skc_list
);
1062 up_write(&spl_kmem_cache_sem
);
1064 /* Cancel any and wait for any pending delayed tasks */
1065 VERIFY(!test_and_set_bit(KMC_BIT_DESTROY
, &skc
->skc_flags
));
1067 spin_lock(&skc
->skc_lock
);
1068 id
= skc
->skc_taskqid
;
1069 spin_unlock(&skc
->skc_lock
);
1071 taskq_cancel_id(spl_kmem_cache_taskq
, id
);
1074 * Wait until all current callers complete, this is mainly
1075 * to catch the case where a low memory situation triggers a
1076 * cache reaping action which races with this destroy.
1078 wait_event(wq
, atomic_read(&skc
->skc_ref
) == 0);
1080 if (skc
->skc_flags
& (KMC_KMEM
| KMC_VMEM
)) {
1081 spl_magazine_destroy(skc
);
1082 spl_slab_reclaim(skc
);
1084 ASSERT(skc
->skc_flags
& KMC_SLAB
);
1085 kmem_cache_destroy(skc
->skc_linux_cache
);
1088 spin_lock(&skc
->skc_lock
);
1091 * Validate there are no objects in use and free all the
1092 * spl_kmem_slab_t, spl_kmem_obj_t, and object buffers.
1094 ASSERT3U(skc
->skc_slab_alloc
, ==, 0);
1095 ASSERT3U(skc
->skc_obj_alloc
, ==, 0);
1096 ASSERT3U(skc
->skc_slab_total
, ==, 0);
1097 ASSERT3U(skc
->skc_obj_total
, ==, 0);
1098 ASSERT3U(skc
->skc_obj_emergency
, ==, 0);
1099 ASSERT(list_empty(&skc
->skc_complete_list
));
1101 spin_unlock(&skc
->skc_lock
);
1103 kfree(skc
->skc_name
);
1106 EXPORT_SYMBOL(spl_kmem_cache_destroy
);
1109 * Allocate an object from a slab attached to the cache. This is used to
1110 * repopulate the per-cpu magazine caches in batches when they run low.
1113 spl_cache_obj(spl_kmem_cache_t
*skc
, spl_kmem_slab_t
*sks
)
1115 spl_kmem_obj_t
*sko
;
1117 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
1118 ASSERT(sks
->sks_magic
== SKS_MAGIC
);
1119 ASSERT(spin_is_locked(&skc
->skc_lock
));
1121 sko
= list_entry(sks
->sks_free_list
.next
, spl_kmem_obj_t
, sko_list
);
1122 ASSERT(sko
->sko_magic
== SKO_MAGIC
);
1123 ASSERT(sko
->sko_addr
!= NULL
);
1125 /* Remove from sks_free_list */
1126 list_del_init(&sko
->sko_list
);
1128 sks
->sks_age
= jiffies
;
1130 skc
->skc_obj_alloc
++;
1132 /* Track max obj usage statistics */
1133 if (skc
->skc_obj_alloc
> skc
->skc_obj_max
)
1134 skc
->skc_obj_max
= skc
->skc_obj_alloc
;
1136 /* Track max slab usage statistics */
1137 if (sks
->sks_ref
== 1) {
1138 skc
->skc_slab_alloc
++;
1140 if (skc
->skc_slab_alloc
> skc
->skc_slab_max
)
1141 skc
->skc_slab_max
= skc
->skc_slab_alloc
;
1144 return (sko
->sko_addr
);
1148 * Generic slab allocation function to run by the global work queues.
1149 * It is responsible for allocating a new slab, linking it in to the list
1150 * of partial slabs, and then waking any waiters.
1153 spl_cache_grow_work(void *data
)
1155 spl_kmem_alloc_t
*ska
= (spl_kmem_alloc_t
*)data
;
1156 spl_kmem_cache_t
*skc
= ska
->ska_cache
;
1157 spl_kmem_slab_t
*sks
;
1159 fstrans_cookie_t cookie
= spl_fstrans_mark();
1160 sks
= spl_slab_alloc(skc
, ska
->ska_flags
);
1161 spl_fstrans_unmark(cookie
);
1163 spin_lock(&skc
->skc_lock
);
1165 skc
->skc_slab_total
++;
1166 skc
->skc_obj_total
+= sks
->sks_objs
;
1167 list_add_tail(&sks
->sks_list
, &skc
->skc_partial_list
);
1170 atomic_dec(&skc
->skc_ref
);
1171 smp_mb__before_atomic();
1172 clear_bit(KMC_BIT_GROWING
, &skc
->skc_flags
);
1173 clear_bit(KMC_BIT_DEADLOCKED
, &skc
->skc_flags
);
1174 smp_mb__after_atomic();
1175 wake_up_all(&skc
->skc_waitq
);
1176 spin_unlock(&skc
->skc_lock
);
1182 * Returns non-zero when a new slab should be available.
1185 spl_cache_grow_wait(spl_kmem_cache_t
*skc
)
1187 return (!test_bit(KMC_BIT_GROWING
, &skc
->skc_flags
));
1191 * No available objects on any slabs, create a new slab. Note that this
1192 * functionality is disabled for KMC_SLAB caches which are backed by the
1196 spl_cache_grow(spl_kmem_cache_t
*skc
, int flags
, void **obj
)
1198 int remaining
, rc
= 0;
1200 ASSERT0(flags
& ~KM_PUBLIC_MASK
);
1201 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
1202 ASSERT((skc
->skc_flags
& KMC_SLAB
) == 0);
1207 * Before allocating a new slab wait for any reaping to complete and
1208 * then return so the local magazine can be rechecked for new objects.
1210 if (test_bit(KMC_BIT_REAPING
, &skc
->skc_flags
)) {
1211 rc
= spl_wait_on_bit(&skc
->skc_flags
, KMC_BIT_REAPING
,
1212 TASK_UNINTERRUPTIBLE
);
1213 return (rc
? rc
: -EAGAIN
);
1217 * This is handled by dispatching a work request to the global work
1218 * queue. This allows us to asynchronously allocate a new slab while
1219 * retaining the ability to safely fall back to a smaller synchronous
1220 * allocations to ensure forward progress is always maintained.
1222 if (test_and_set_bit(KMC_BIT_GROWING
, &skc
->skc_flags
) == 0) {
1223 spl_kmem_alloc_t
*ska
;
1225 ska
= kmalloc(sizeof (*ska
), kmem_flags_convert(flags
));
1227 clear_bit_unlock(KMC_BIT_GROWING
, &skc
->skc_flags
);
1228 smp_mb__after_atomic();
1229 wake_up_all(&skc
->skc_waitq
);
1233 atomic_inc(&skc
->skc_ref
);
1234 ska
->ska_cache
= skc
;
1235 ska
->ska_flags
= flags
;
1236 taskq_init_ent(&ska
->ska_tqe
);
1237 taskq_dispatch_ent(spl_kmem_cache_taskq
,
1238 spl_cache_grow_work
, ska
, 0, &ska
->ska_tqe
);
1242 * The goal here is to only detect the rare case where a virtual slab
1243 * allocation has deadlocked. We must be careful to minimize the use
1244 * of emergency objects which are more expensive to track. Therefore,
1245 * we set a very long timeout for the asynchronous allocation and if
1246 * the timeout is reached the cache is flagged as deadlocked. From
1247 * this point only new emergency objects will be allocated until the
1248 * asynchronous allocation completes and clears the deadlocked flag.
1250 if (test_bit(KMC_BIT_DEADLOCKED
, &skc
->skc_flags
)) {
1251 rc
= spl_emergency_alloc(skc
, flags
, obj
);
1253 remaining
= wait_event_timeout(skc
->skc_waitq
,
1254 spl_cache_grow_wait(skc
), HZ
/ 10);
1257 spin_lock(&skc
->skc_lock
);
1258 if (test_bit(KMC_BIT_GROWING
, &skc
->skc_flags
)) {
1259 set_bit(KMC_BIT_DEADLOCKED
, &skc
->skc_flags
);
1260 skc
->skc_obj_deadlock
++;
1262 spin_unlock(&skc
->skc_lock
);
1272 * Refill a per-cpu magazine with objects from the slabs for this cache.
1273 * Ideally the magazine can be repopulated using existing objects which have
1274 * been released, however if we are unable to locate enough free objects new
1275 * slabs of objects will be created. On success NULL is returned, otherwise
1276 * the address of a single emergency object is returned for use by the caller.
1279 spl_cache_refill(spl_kmem_cache_t
*skc
, spl_kmem_magazine_t
*skm
, int flags
)
1281 spl_kmem_slab_t
*sks
;
1282 int count
= 0, rc
, refill
;
1285 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
1286 ASSERT(skm
->skm_magic
== SKM_MAGIC
);
1288 refill
= MIN(skm
->skm_refill
, skm
->skm_size
- skm
->skm_avail
);
1289 spin_lock(&skc
->skc_lock
);
1291 while (refill
> 0) {
1292 /* No slabs available we may need to grow the cache */
1293 if (list_empty(&skc
->skc_partial_list
)) {
1294 spin_unlock(&skc
->skc_lock
);
1297 rc
= spl_cache_grow(skc
, flags
, &obj
);
1298 local_irq_disable();
1300 /* Emergency object for immediate use by caller */
1301 if (rc
== 0 && obj
!= NULL
)
1307 /* Rescheduled to different CPU skm is not local */
1308 if (skm
!= skc
->skc_mag
[smp_processor_id()])
1312 * Potentially rescheduled to the same CPU but
1313 * allocations may have occurred from this CPU while
1314 * we were sleeping so recalculate max refill.
1316 refill
= MIN(refill
, skm
->skm_size
- skm
->skm_avail
);
1318 spin_lock(&skc
->skc_lock
);
1322 /* Grab the next available slab */
1323 sks
= list_entry((&skc
->skc_partial_list
)->next
,
1324 spl_kmem_slab_t
, sks_list
);
1325 ASSERT(sks
->sks_magic
== SKS_MAGIC
);
1326 ASSERT(sks
->sks_ref
< sks
->sks_objs
);
1327 ASSERT(!list_empty(&sks
->sks_free_list
));
1330 * Consume as many objects as needed to refill the requested
1331 * cache. We must also be careful not to overfill it.
1333 while (sks
->sks_ref
< sks
->sks_objs
&& refill
-- > 0 &&
1335 ASSERT(skm
->skm_avail
< skm
->skm_size
);
1336 ASSERT(count
< skm
->skm_size
);
1337 skm
->skm_objs
[skm
->skm_avail
++] =
1338 spl_cache_obj(skc
, sks
);
1341 /* Move slab to skc_complete_list when full */
1342 if (sks
->sks_ref
== sks
->sks_objs
) {
1343 list_del(&sks
->sks_list
);
1344 list_add(&sks
->sks_list
, &skc
->skc_complete_list
);
1348 spin_unlock(&skc
->skc_lock
);
1354 * Release an object back to the slab from which it came.
1357 spl_cache_shrink(spl_kmem_cache_t
*skc
, void *obj
)
1359 spl_kmem_slab_t
*sks
= NULL
;
1360 spl_kmem_obj_t
*sko
= NULL
;
1362 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
1363 ASSERT(spin_is_locked(&skc
->skc_lock
));
1365 sko
= spl_sko_from_obj(skc
, obj
);
1366 ASSERT(sko
->sko_magic
== SKO_MAGIC
);
1367 sks
= sko
->sko_slab
;
1368 ASSERT(sks
->sks_magic
== SKS_MAGIC
);
1369 ASSERT(sks
->sks_cache
== skc
);
1370 list_add(&sko
->sko_list
, &sks
->sks_free_list
);
1372 sks
->sks_age
= jiffies
;
1374 skc
->skc_obj_alloc
--;
1377 * Move slab to skc_partial_list when no longer full. Slabs
1378 * are added to the head to keep the partial list is quasi-full
1379 * sorted order. Fuller at the head, emptier at the tail.
1381 if (sks
->sks_ref
== (sks
->sks_objs
- 1)) {
1382 list_del(&sks
->sks_list
);
1383 list_add(&sks
->sks_list
, &skc
->skc_partial_list
);
1387 * Move empty slabs to the end of the partial list so
1388 * they can be easily found and freed during reclamation.
1390 if (sks
->sks_ref
== 0) {
1391 list_del(&sks
->sks_list
);
1392 list_add_tail(&sks
->sks_list
, &skc
->skc_partial_list
);
1393 skc
->skc_slab_alloc
--;
1398 * Allocate an object from the per-cpu magazine, or if the magazine
1399 * is empty directly allocate from a slab and repopulate the magazine.
1402 spl_kmem_cache_alloc(spl_kmem_cache_t
*skc
, int flags
)
1404 spl_kmem_magazine_t
*skm
;
1407 ASSERT0(flags
& ~KM_PUBLIC_MASK
);
1408 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
1409 ASSERT(!test_bit(KMC_BIT_DESTROY
, &skc
->skc_flags
));
1412 * Allocate directly from a Linux slab. All optimizations are left
1413 * to the underlying cache we only need to guarantee that KM_SLEEP
1414 * callers will never fail.
1416 if (skc
->skc_flags
& KMC_SLAB
) {
1417 struct kmem_cache
*slc
= skc
->skc_linux_cache
;
1419 obj
= kmem_cache_alloc(slc
, kmem_flags_convert(flags
));
1420 } while ((obj
== NULL
) && !(flags
& KM_NOSLEEP
));
1425 local_irq_disable();
1429 * Safe to update per-cpu structure without lock, but
1430 * in the restart case we must be careful to reacquire
1431 * the local magazine since this may have changed
1432 * when we need to grow the cache.
1434 skm
= skc
->skc_mag
[smp_processor_id()];
1435 ASSERT(skm
->skm_magic
== SKM_MAGIC
);
1437 if (likely(skm
->skm_avail
)) {
1438 /* Object available in CPU cache, use it */
1439 obj
= skm
->skm_objs
[--skm
->skm_avail
];
1440 skm
->skm_age
= jiffies
;
1442 obj
= spl_cache_refill(skc
, skm
, flags
);
1443 if ((obj
== NULL
) && !(flags
& KM_NOSLEEP
))
1452 ASSERT(IS_P2ALIGNED(obj
, skc
->skc_obj_align
));
1455 /* Pre-emptively migrate object to CPU L1 cache */
1457 if (obj
&& skc
->skc_ctor
)
1458 skc
->skc_ctor(obj
, skc
->skc_private
, flags
);
1465 EXPORT_SYMBOL(spl_kmem_cache_alloc
);
1468 * Free an object back to the local per-cpu magazine, there is no
1469 * guarantee that this is the same magazine the object was originally
1470 * allocated from. We may need to flush entire from the magazine
1471 * back to the slabs to make space.
1474 spl_kmem_cache_free(spl_kmem_cache_t
*skc
, void *obj
)
1476 spl_kmem_magazine_t
*skm
;
1477 unsigned long flags
;
1479 int do_emergency
= 0;
1481 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
1482 ASSERT(!test_bit(KMC_BIT_DESTROY
, &skc
->skc_flags
));
1485 * Run the destructor
1488 skc
->skc_dtor(obj
, skc
->skc_private
);
1491 * Free the object from the Linux underlying Linux slab.
1493 if (skc
->skc_flags
& KMC_SLAB
) {
1494 kmem_cache_free(skc
->skc_linux_cache
, obj
);
1499 * While a cache has outstanding emergency objects all freed objects
1500 * must be checked. However, since emergency objects will never use
1501 * a virtual address these objects can be safely excluded as an
1504 if (!is_vmalloc_addr(obj
)) {
1505 spin_lock(&skc
->skc_lock
);
1506 do_emergency
= (skc
->skc_obj_emergency
> 0);
1507 spin_unlock(&skc
->skc_lock
);
1509 if (do_emergency
&& (spl_emergency_free(skc
, obj
) == 0))
1513 local_irq_save(flags
);
1516 * Safe to update per-cpu structure without lock, but
1517 * no remote memory allocation tracking is being performed
1518 * it is entirely possible to allocate an object from one
1519 * CPU cache and return it to another.
1521 skm
= skc
->skc_mag
[smp_processor_id()];
1522 ASSERT(skm
->skm_magic
== SKM_MAGIC
);
1525 * Per-CPU cache full, flush it to make space for this object,
1526 * this may result in an empty slab which can be reclaimed once
1527 * interrupts are re-enabled.
1529 if (unlikely(skm
->skm_avail
>= skm
->skm_size
)) {
1530 spl_cache_flush(skc
, skm
, skm
->skm_refill
);
1534 /* Available space in cache, use it */
1535 skm
->skm_objs
[skm
->skm_avail
++] = obj
;
1537 local_irq_restore(flags
);
1540 spl_slab_reclaim(skc
);
1542 EXPORT_SYMBOL(spl_kmem_cache_free
);
1545 * The generic shrinker function for all caches. Under Linux a shrinker
1546 * may not be tightly coupled with a slab cache. In fact Linux always
1547 * systematically tries calling all registered shrinker callbacks which
1548 * report that they contain unused objects. Because of this we only
1549 * register one shrinker function in the shim layer for all slab caches.
1550 * We always attempt to shrink all caches when this generic shrinker
1553 * If sc->nr_to_scan is zero, the caller is requesting a query of the
1554 * number of objects which can potentially be freed. If it is nonzero,
1555 * the request is to free that many objects.
1557 * Linux kernels >= 3.12 have the count_objects and scan_objects callbacks
1558 * in struct shrinker and also require the shrinker to return the number
1561 * Older kernels require the shrinker to return the number of freeable
1562 * objects following the freeing of nr_to_free.
1564 * Linux semantics differ from those under Solaris, which are to
1565 * free all available objects which may (and probably will) be more
1566 * objects than the requested nr_to_scan.
1568 static spl_shrinker_t
1569 __spl_kmem_cache_generic_shrinker(struct shrinker
*shrink
,
1570 struct shrink_control
*sc
)
1572 spl_kmem_cache_t
*skc
;
1576 * No shrinking in a transaction context. Can cause deadlocks.
1578 if (sc
->nr_to_scan
&& spl_fstrans_check())
1579 return (SHRINK_STOP
);
1581 down_read(&spl_kmem_cache_sem
);
1582 list_for_each_entry(skc
, &spl_kmem_cache_list
, skc_list
) {
1583 if (sc
->nr_to_scan
) {
1584 #ifdef HAVE_SPLIT_SHRINKER_CALLBACK
1585 uint64_t oldalloc
= skc
->skc_obj_alloc
;
1586 spl_kmem_cache_reap_now(skc
,
1587 MAX(sc
->nr_to_scan
>>fls64(skc
->skc_slab_objs
), 1));
1588 if (oldalloc
> skc
->skc_obj_alloc
)
1589 alloc
+= oldalloc
- skc
->skc_obj_alloc
;
1591 spl_kmem_cache_reap_now(skc
,
1592 MAX(sc
->nr_to_scan
>>fls64(skc
->skc_slab_objs
), 1));
1593 alloc
+= skc
->skc_obj_alloc
;
1594 #endif /* HAVE_SPLIT_SHRINKER_CALLBACK */
1596 /* Request to query number of freeable objects */
1597 alloc
+= skc
->skc_obj_alloc
;
1600 up_read(&spl_kmem_cache_sem
);
1603 * When KMC_RECLAIM_ONCE is set allow only a single reclaim pass.
1604 * This functionality only exists to work around a rare issue where
1605 * shrink_slabs() is repeatedly invoked by many cores causing the
1608 if ((spl_kmem_cache_reclaim
& KMC_RECLAIM_ONCE
) && sc
->nr_to_scan
)
1609 return (SHRINK_STOP
);
1611 return (MAX(alloc
, 0));
1614 SPL_SHRINKER_CALLBACK_WRAPPER(spl_kmem_cache_generic_shrinker
);
1617 * Call the registered reclaim function for a cache. Depending on how
1618 * many and which objects are released it may simply repopulate the
1619 * local magazine which will then need to age-out. Objects which cannot
1620 * fit in the magazine we will be released back to their slabs which will
1621 * also need to age out before being release. This is all just best
1622 * effort and we do not want to thrash creating and destroying slabs.
1625 spl_kmem_cache_reap_now(spl_kmem_cache_t
*skc
, int count
)
1627 ASSERT(skc
->skc_magic
== SKC_MAGIC
);
1628 ASSERT(!test_bit(KMC_BIT_DESTROY
, &skc
->skc_flags
));
1630 atomic_inc(&skc
->skc_ref
);
1633 * Execute the registered reclaim callback if it exists.
1635 if (skc
->skc_flags
& KMC_SLAB
) {
1636 if (skc
->skc_reclaim
)
1637 skc
->skc_reclaim(skc
->skc_private
);
1642 * Prevent concurrent cache reaping when contended.
1644 if (test_and_set_bit(KMC_BIT_REAPING
, &skc
->skc_flags
))
1648 * When a reclaim function is available it may be invoked repeatedly
1649 * until at least a single slab can be freed. This ensures that we
1650 * do free memory back to the system. This helps minimize the chance
1651 * of an OOM event when the bulk of memory is used by the slab.
1653 * When free slabs are already available the reclaim callback will be
1654 * skipped. Additionally, if no forward progress is detected despite
1655 * a reclaim function the cache will be skipped to avoid deadlock.
1657 * Longer term this would be the correct place to add the code which
1658 * repacks the slabs in order minimize fragmentation.
1660 if (skc
->skc_reclaim
) {
1661 uint64_t objects
= UINT64_MAX
;
1665 spin_lock(&skc
->skc_lock
);
1667 (skc
->skc_slab_total
> 0) &&
1668 ((skc
->skc_slab_total
-skc
->skc_slab_alloc
) == 0) &&
1669 (skc
->skc_obj_alloc
< objects
);
1671 objects
= skc
->skc_obj_alloc
;
1672 spin_unlock(&skc
->skc_lock
);
1675 skc
->skc_reclaim(skc
->skc_private
);
1677 } while (do_reclaim
);
1680 /* Reclaim from the magazine and free all now empty slabs. */
1681 if (spl_kmem_cache_expire
& KMC_EXPIRE_MEM
) {
1682 spl_kmem_magazine_t
*skm
;
1683 unsigned long irq_flags
;
1685 local_irq_save(irq_flags
);
1686 skm
= skc
->skc_mag
[smp_processor_id()];
1687 spl_cache_flush(skc
, skm
, skm
->skm_avail
);
1688 local_irq_restore(irq_flags
);
1691 spl_slab_reclaim(skc
);
1692 clear_bit_unlock(KMC_BIT_REAPING
, &skc
->skc_flags
);
1693 smp_mb__after_atomic();
1694 wake_up_bit(&skc
->skc_flags
, KMC_BIT_REAPING
);
1696 atomic_dec(&skc
->skc_ref
);
1698 EXPORT_SYMBOL(spl_kmem_cache_reap_now
);
1701 * Reap all free slabs from all registered caches.
1706 struct shrink_control sc
;
1708 sc
.nr_to_scan
= KMC_REAP_CHUNK
;
1709 sc
.gfp_mask
= GFP_KERNEL
;
1711 (void) __spl_kmem_cache_generic_shrinker(NULL
, &sc
);
1713 EXPORT_SYMBOL(spl_kmem_reap
);
1716 spl_kmem_cache_init(void)
1718 init_rwsem(&spl_kmem_cache_sem
);
1719 INIT_LIST_HEAD(&spl_kmem_cache_list
);
1720 spl_kmem_cache_taskq
= taskq_create("spl_kmem_cache",
1721 spl_kmem_cache_kmem_threads
, maxclsyspri
,
1722 spl_kmem_cache_kmem_threads
* 8, INT_MAX
,
1723 TASKQ_PREPOPULATE
| TASKQ_DYNAMIC
);
1724 spl_register_shrinker(&spl_kmem_cache_shrinker
);
1730 spl_kmem_cache_fini(void)
1732 spl_unregister_shrinker(&spl_kmem_cache_shrinker
);
1733 taskq_destroy(spl_kmem_cache_taskq
);