2 * Copyright (c) 2005 Jeffrey M. Hsu. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of The DragonFly Project nor the names of its
16 * contributors may be used to endorse or promote products derived
17 * from this software without specific, prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
22 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
23 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
24 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
25 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
26 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
27 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
28 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
29 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * $DragonFly: src/sys/kern/kern_objcache.c,v 1.13 2006/12/02 22:17:22 dillon Exp $
35 #include <sys/param.h>
36 #include <sys/kernel.h>
37 #include <sys/systm.h>
38 #include <sys/callout.h>
39 #include <sys/globaldata.h>
40 #include <sys/malloc.h>
41 #include <sys/queue.h>
42 #include <sys/objcache.h>
43 #include <sys/spinlock.h>
44 #include <sys/thread.h>
45 #include <sys/thread2.h>
46 #include <sys/spinlock2.h>
48 static MALLOC_DEFINE(M_OBJCACHE, "objcache", "Object Cache");
49 static MALLOC_DEFINE(M_OBJMAG, "objcache magazine", "Object Cache Magazine");
51 #define INITIAL_MAG_CAPACITY 256
57 SLIST_ENTRY(magazine) nextmagazine;
61 SLIST_HEAD(magazinelist, magazine);
64 * per-cluster cache of magazines
66 * All fields in this structure are protected by the spinlock.
68 struct magazinedepot {
70 * The per-cpu object caches only exchanges completely full or
71 * completely empty magazines with the depot layer, so only have
72 * to cache these two types of magazines.
74 struct magazinelist fullmagazines;
75 struct magazinelist emptymagazines;
78 /* protect this structure */
81 /* magazines not yet allocated towards limit */
82 int unallocated_objects;
84 /* infrequently used fields */
85 int waiting; /* waiting for another cpu to
86 * return a full magazine to
88 int contested; /* depot contention count */
92 * per-cpu object cache
93 * All fields in this structure are protected by crit_enter().
95 struct percpu_objcache {
96 struct magazine *loaded_magazine; /* active magazine */
97 struct magazine *previous_magazine; /* backup magazine */
100 int gets_cumulative; /* total calls to get */
101 int gets_null; /* objcache_get returned NULL */
102 int puts_cumulative; /* total calls to put */
103 int puts_othercluster; /* returned to other cluster */
105 /* infrequently used fields */
106 int waiting; /* waiting for a thread on this cpu to
107 * return an obj to the per-cpu cache */
110 /* only until we have NUMA cluster topology information XXX */
111 #define MAXCLUSTERS 1
112 #define myclusterid 0
113 #define CLUSTER_OF(obj) 0
116 * Two-level object cache consisting of NUMA cluster-level depots of
117 * fully loaded or completely empty magazines and cpu-level caches of
118 * individual objects.
123 /* object constructor and destructor from blank storage */
124 objcache_ctor_fn *ctor;
125 objcache_dtor_fn *dtor;
128 /* interface to underlying allocator */
129 objcache_alloc_fn *alloc;
130 objcache_free_fn *free;
131 void *allocator_args;
132 size_t simple_objsize;
134 SLIST_ENTRY(objcache) oc_next;
136 /* NUMA-cluster level caches */
137 struct magazinedepot depot[MAXCLUSTERS];
139 struct percpu_objcache cache_percpu[]; /* per-cpu caches */
142 static struct spinlock objcachelist_spin;
143 static SLIST_HEAD(objcachelist, objcache) allobjcaches;
145 static struct magazine *
146 mag_alloc(int capacity)
148 struct magazine *mag;
150 mag = kmalloc(__offsetof(struct magazine, objects[capacity]),
151 M_OBJMAG, M_INTWAIT | M_ZERO);
152 mag->capacity = capacity;
159 * Create an object cache.
162 objcache_create(const char *name, int cluster_limit, int mag_capacity,
163 objcache_ctor_fn *ctor, objcache_dtor_fn *dtor, void *private,
164 objcache_alloc_fn *alloc, objcache_free_fn *free,
165 void *allocator_args)
168 struct magazinedepot *depot;
171 /* allocate object cache structure */
172 oc = kmalloc(__offsetof(struct objcache, cache_percpu[ncpus]),
173 M_OBJCACHE, M_WAITOK | M_ZERO);
174 oc->name = kstrdup(name, M_TEMP);
177 oc->private = private;
179 oc->allocator_args = allocator_args;
181 /* initialize depots */
182 depot = &oc->depot[0];
184 spin_init(&depot->spin);
185 SLIST_INIT(&depot->fullmagazines);
186 SLIST_INIT(&depot->emptymagazines);
188 if (mag_capacity == 0)
189 mag_capacity = INITIAL_MAG_CAPACITY;
190 depot->magcapacity = mag_capacity;
193 * The cluster_limit must be sufficient to have three magazines per
196 if (cluster_limit == 0) {
197 depot->unallocated_objects = -1;
199 if (cluster_limit < mag_capacity * ncpus * 3)
200 cluster_limit = mag_capacity * ncpus * 3;
201 depot->unallocated_objects = cluster_limit;
205 /* initialize per-cpu caches */
206 for (cpuid = 0; cpuid < ncpus; cpuid++) {
207 struct percpu_objcache *cache_percpu = &oc->cache_percpu[cpuid];
209 cache_percpu->loaded_magazine = mag_alloc(mag_capacity);
210 cache_percpu->previous_magazine = mag_alloc(mag_capacity);
212 spin_lock_wr(&objcachelist_spin);
213 SLIST_INSERT_HEAD(&allobjcaches, oc, oc_next);
214 spin_unlock_wr(&objcachelist_spin);
220 objcache_create_simple(malloc_type_t mtype, size_t objsize)
222 struct objcache_malloc_args *margs;
225 margs = kmalloc(sizeof(*margs), M_OBJCACHE, M_WAITOK|M_ZERO);
226 margs->objsize = objsize;
227 margs->mtype = mtype;
228 oc = objcache_create(mtype->ks_shortdesc, 0, 0,
229 null_ctor, null_dtor, NULL,
230 objcache_malloc_alloc, objcache_malloc_free,
234 * This indicates that we are a simple objcache and allows
235 * objcache_get() calls with M_ZERO.
237 oc->simple_objsize = objsize;
241 #define MAGAZINE_EMPTY(mag) (mag->rounds == 0)
242 #define MAGAZINE_NOTEMPTY(mag) (mag->rounds != 0)
243 #define MAGAZINE_FULL(mag) (mag->rounds == mag->capacity)
245 #define swap(x, y) ({ struct magazine *t = x; x = y; y = t; })
248 * Get an object from the object cache.
250 * WARNING! ocflags are only used when we have to go to the underlying
251 * allocator, so we cannot depend on flags such as M_ZERO.
254 objcache_get(struct objcache *oc, int ocflags)
256 struct percpu_objcache *cpucache = &oc->cache_percpu[mycpuid];
257 struct magazine *loadedmag;
258 struct magazine *emptymag;
260 struct magazinedepot *depot;
263 ++cpucache->gets_cumulative;
267 * Loaded magazine has an object. This is the hot path.
268 * It is lock-free and uses a critical section to block
269 * out interrupt handlers on the same processor.
271 loadedmag = cpucache->loaded_magazine;
272 if (MAGAZINE_NOTEMPTY(loadedmag)) {
273 obj = loadedmag->objects[--loadedmag->rounds];
276 if (ocflags & M_ZERO) {
277 if (oc->simple_objsize)
278 bzero(obj, oc->simple_objsize);
280 panic("objcache_get(): M_ZERO illegal here");
285 /* Previous magazine has an object. */
286 if (MAGAZINE_NOTEMPTY(cpucache->previous_magazine)) {
287 KKASSERT(cpucache->previous_magazine->cleaning +
288 cpucache->loaded_magazine->cleaning == 0);
289 swap(cpucache->loaded_magazine, cpucache->previous_magazine);
290 loadedmag = cpucache->loaded_magazine;
291 obj = loadedmag->objects[--loadedmag->rounds];
296 * Both magazines empty. Get a full magazine from the depot and
297 * move one of the empty ones to the depot.
299 * Obtain the depot spinlock.
301 * NOTE: Beyond this point, M_ZERO is handled via oc->alloc()
303 depot = &oc->depot[myclusterid];
304 spin_lock_wr(&depot->spin);
307 * Recheck the cpucache after obtaining the depot spinlock. This
308 * shouldn't be necessary now but don't take any chances.
310 if (MAGAZINE_NOTEMPTY(cpucache->loaded_magazine) ||
311 MAGAZINE_NOTEMPTY(cpucache->previous_magazine)
313 spin_unlock_wr(&depot->spin);
317 /* Check if depot has a full magazine. */
318 if (!SLIST_EMPTY(&depot->fullmagazines)) {
319 emptymag = cpucache->previous_magazine;
320 cpucache->previous_magazine = cpucache->loaded_magazine;
321 cpucache->loaded_magazine = SLIST_FIRST(&depot->fullmagazines);
322 SLIST_REMOVE_HEAD(&depot->fullmagazines, nextmagazine);
325 * Return emptymag to the depot.
327 KKASSERT(MAGAZINE_EMPTY(emptymag));
328 SLIST_INSERT_HEAD(&depot->emptymagazines,
329 emptymag, nextmagazine);
330 spin_unlock_wr(&depot->spin);
335 * The depot does not have any non-empty magazines. If we have
336 * not hit our object limit we can allocate a new object using
337 * the back-end allocator.
339 * note: unallocated_objects can be initialized to -1, which has
340 * the effect of removing any allocation limits.
342 if (depot->unallocated_objects) {
343 --depot->unallocated_objects;
344 spin_unlock_wr(&depot->spin);
347 obj = oc->alloc(oc->allocator_args, ocflags);
349 if (oc->ctor(obj, oc->private, ocflags))
351 oc->free(obj, oc->allocator_args);
352 spin_lock_wr(&depot->spin);
353 ++depot->unallocated_objects;
354 spin_unlock_wr(&depot->spin);
362 * makes debugging easier when gets_cumulative does
363 * not include gets_null.
365 ++cpucache->gets_null;
366 --cpucache->gets_cumulative;
373 * Otherwise block if allowed to.
375 if ((ocflags & (M_WAITOK|M_NULLOK)) == M_WAITOK) {
378 msleep(depot, &depot->spin, 0, "objcache_get", 0);
381 spin_unlock_wr(&depot->spin);
388 ++cpucache->gets_null;
389 --cpucache->gets_cumulative;
391 spin_unlock_wr(&depot->spin);
396 * Wrapper for malloc allocation routines.
399 objcache_malloc_alloc(void *allocator_args, int ocflags)
401 struct objcache_malloc_args *alloc_args = allocator_args;
403 return (kmalloc(alloc_args->objsize, alloc_args->mtype,
404 ocflags & OC_MFLAGS));
408 objcache_malloc_free(void *obj, void *allocator_args)
410 struct objcache_malloc_args *alloc_args = allocator_args;
412 kfree(obj, alloc_args->mtype);
416 * Wrapper for allocation policies that pre-allocate at initialization time
417 * and don't do run-time allocation.
420 objcache_nop_alloc(void *allocator_args, int ocflags)
426 objcache_nop_free(void *obj, void *allocator_args)
431 * Return an object to the object cache.
434 objcache_put(struct objcache *oc, void *obj)
436 struct percpu_objcache *cpucache = &oc->cache_percpu[mycpuid];
437 struct magazine *loadedmag;
438 struct magazinedepot *depot;
441 ++cpucache->puts_cumulative;
443 if (CLUSTER_OF(obj) != myclusterid) {
445 /* use lazy IPI to send object to owning cluster XXX todo */
446 ++cpucache->puts_othercluster;
454 * Free slot available in loaded magazine. This is the hot path.
455 * It is lock-free and uses a critical section to block out interrupt
456 * handlers on the same processor.
458 loadedmag = cpucache->loaded_magazine;
459 if (!MAGAZINE_FULL(loadedmag)) {
460 loadedmag->objects[loadedmag->rounds++] = obj;
461 if (cpucache->waiting)
462 wakeup_mycpu(&oc->depot[myclusterid]);
468 * Current magazine full, but previous magazine has room. XXX
470 if (!MAGAZINE_FULL(cpucache->previous_magazine)) {
471 KKASSERT(cpucache->previous_magazine->cleaning +
472 cpucache->loaded_magazine->cleaning == 0);
473 swap(cpucache->loaded_magazine, cpucache->previous_magazine);
474 loadedmag = cpucache->loaded_magazine;
475 loadedmag->objects[loadedmag->rounds++] = obj;
476 if (cpucache->waiting)
477 wakeup_mycpu(&oc->depot[myclusterid]);
483 * Both magazines full. Get an empty magazine from the depot and
484 * move a full loaded magazine to the depot. Even though the
485 * magazine may wind up with space available after we block on
486 * the spinlock, we still cycle it through to avoid the non-optimal
489 * Obtain the depot spinlock.
491 depot = &oc->depot[myclusterid];
492 spin_lock_wr(&depot->spin);
495 * If an empty magazine is available in the depot, cycle it
498 if (!SLIST_EMPTY(&depot->emptymagazines)) {
499 KKASSERT(cpucache->previous_magazine->cleaning +
500 cpucache->loaded_magazine->cleaning == 0);
501 loadedmag = cpucache->previous_magazine;
502 cpucache->previous_magazine = cpucache->loaded_magazine;
503 cpucache->loaded_magazine = SLIST_FIRST(&depot->emptymagazines);
504 SLIST_REMOVE_HEAD(&depot->emptymagazines, nextmagazine);
507 * Return loadedmag to the depot. Due to blocking it may
508 * not be entirely full and could even be empty.
510 if (MAGAZINE_EMPTY(loadedmag)) {
511 SLIST_INSERT_HEAD(&depot->emptymagazines,
512 loadedmag, nextmagazine);
513 spin_unlock_wr(&depot->spin);
515 SLIST_INSERT_HEAD(&depot->fullmagazines,
516 loadedmag, nextmagazine);
517 spin_unlock_wr(&depot->spin);
525 * An empty mag is not available. This is a corner case which can
526 * occur due to cpus holding partially full magazines. Do not try
527 * to allocate a mag, just free the object.
529 ++depot->unallocated_objects;
530 spin_unlock_wr(&depot->spin);
534 oc->dtor(obj, oc->private);
535 oc->free(obj, oc->allocator_args);
539 * The object is being put back into the cache, but the caller has
540 * indicated that the object is not in any shape to be reused and should
541 * be dtor'd immediately.
544 objcache_dtor(struct objcache *oc, void *obj)
546 struct magazinedepot *depot;
548 depot = &oc->depot[myclusterid];
549 spin_lock_wr(&depot->spin);
550 ++depot->unallocated_objects;
551 spin_unlock_wr(&depot->spin);
554 oc->dtor(obj, oc->private);
555 oc->free(obj, oc->allocator_args);
559 * Utility routine for objects that don't require any de-construction.
562 null_dtor(void *obj, void *private)
568 null_ctor(void *obj, void *private, int ocflags)
574 * Deallocate all objects in a magazine and free the magazine if requested.
575 * The magazine must already be disassociated from the depot.
577 * Must be called with a critical section held when called with a per-cpu
578 * magazine. The magazine may be indirectly modified during the loop.
580 * The number of objects freed is returned.
583 mag_purge(struct objcache *oc, struct magazine *mag, int freeit)
590 while (mag->rounds) {
591 obj = mag->objects[--mag->rounds];
592 oc->dtor(obj, oc->private); /* MAY BLOCK */
593 oc->free(obj, oc->allocator_args); /* MAY BLOCK */
597 * Cycle for interrupts
599 if ((count & 15) == 0) {
606 kfree(mag, M_OBJMAG);
611 * Disassociate zero or more magazines from a magazine list associated with
612 * the depot, update the depot, and move the magazines to a temporary
615 * The caller must check the depot for waiters and wake it up, typically
616 * after disposing of the magazines this function loads onto the temporary
620 maglist_disassociate(struct magazinedepot *depot, struct magazinelist *maglist,
621 struct magazinelist *tmplist, boolean_t purgeall)
623 struct magazine *mag;
625 while ((mag = SLIST_FIRST(maglist)) != NULL) {
626 SLIST_REMOVE_HEAD(maglist, nextmagazine);
627 SLIST_INSERT_HEAD(tmplist, mag, nextmagazine);
628 depot->unallocated_objects += mag->rounds;
633 * Deallocate all magazines and their contents from the passed temporary
634 * list. The magazines have already been accounted for by their depots.
636 * The total number of rounds freed is returned. This number is typically
637 * only used to determine whether a wakeup on the depot is needed or not.
640 maglist_purge(struct objcache *oc, struct magazinelist *maglist)
642 struct magazine *mag;
646 * can't use SLIST_FOREACH because blocking releases the depot
649 while ((mag = SLIST_FIRST(maglist)) != NULL) {
650 SLIST_REMOVE_HEAD(maglist, nextmagazine);
651 count += mag_purge(oc, mag, TRUE);
657 * De-allocates all magazines on the full and empty magazine lists.
659 * Because this routine is called with a spinlock held, the magazines
660 * can only be disassociated and moved to a temporary list, not freed.
662 * The caller is responsible for freeing the magazines.
665 depot_disassociate(struct magazinedepot *depot, struct magazinelist *tmplist)
667 maglist_disassociate(depot, &depot->fullmagazines, tmplist, TRUE);
668 maglist_disassociate(depot, &depot->emptymagazines, tmplist, TRUE);
673 objcache_reclaim(struct objcache *oc)
675 struct percpu_objcache *cache_percpu = &oc->cache_percpu[myclusterid];
676 struct magazinedepot *depot = &oc->depot[myclusterid];
677 struct magazinelist tmplist;
680 SLIST_INIT(&tmplist);
682 count = mag_purge(oc, cache_percpu->loaded_magazine, FALSE);
683 count += mag_purge(oc, cache_percpu->previous_magazine, FALSE);
686 spin_lock_wr(&depot->spin);
687 depot->unallocated_objects += count;
688 depot_disassociate(depot, &tmplist);
689 spin_unlock_wr(&depot->spin);
690 count += maglist_purge(oc, &tmplist);
691 if (count && depot->waiting)
697 * Try to free up some memory. Return as soon as some free memory is found.
698 * For each object cache on the reclaim list, first try the current per-cpu
699 * cache, then the full magazine depot.
702 objcache_reclaimlist(struct objcache *oclist[], int nlist, int ocflags)
705 struct percpu_objcache *cpucache;
706 struct magazinedepot *depot;
707 struct magazinelist tmplist;
710 SLIST_INIT(&tmplist);
712 for (i = 0; i < nlist; i++) {
714 cpucache = &oc->cache_percpu[mycpuid];
715 depot = &oc->depot[myclusterid];
718 count = mag_purge(oc, cpucache->loaded_magazine, FALSE);
720 count += mag_purge(oc, cpucache->previous_magazine, FALSE);
723 spin_lock_wr(&depot->spin);
724 depot->unallocated_objects += count;
725 spin_unlock_wr(&depot->spin);
731 spin_lock_wr(&depot->spin);
732 maglist_disassociate(depot, &depot->fullmagazines,
734 spin_unlock_wr(&depot->spin);
735 count = maglist_purge(oc, &tmplist);
746 * Destroy an object cache. Must have no existing references.
749 objcache_destroy(struct objcache *oc)
751 struct percpu_objcache *cache_percpu;
752 struct magazinedepot *depot;
753 int clusterid, cpuid;
754 struct magazinelist tmplist;
756 SLIST_INIT(&tmplist);
757 for (clusterid = 0; clusterid < MAXCLUSTERS; clusterid++) {
758 depot = &oc->depot[clusterid];
759 spin_lock_wr(&depot->spin);
760 depot_disassociate(depot, &tmplist);
761 spin_unlock_wr(&depot->spin);
763 maglist_purge(oc, &tmplist);
765 for (cpuid = 0; cpuid < ncpus; cpuid++) {
766 cache_percpu = &oc->cache_percpu[cpuid];
768 mag_purge(oc, cache_percpu->loaded_magazine, TRUE);
769 mag_purge(oc, cache_percpu->previous_magazine, TRUE);
770 cache_percpu->loaded_magazine = NULL;
771 cache_percpu->previous_magazine = NULL;
772 /* don't bother adjusting depot->unallocated_objects */
775 kfree(oc->name, M_TEMP);
776 kfree(oc, M_OBJCACHE);
781 * Populate the per-cluster depot with elements from a linear block
782 * of memory. Must be called for individually for each cluster.
783 * Populated depots should not be destroyed.
786 objcache_populate_linear(struct objcache *oc, void *base, int nelts, int size)
789 char *end = (char *)base + (nelts * size);
790 struct magazinedepot *depot = &oc->depot[myclusterid];
791 struct magazine *emptymag = mag_alloc(depot->magcapcity);
794 emptymag->objects[emptymag->rounds++] = p;
795 if (MAGAZINE_FULL(emptymag)) {
796 spin_lock_wr(&depot->spin);
797 SLIST_INSERT_HEAD(&depot->fullmagazines, emptymag,
799 depot->unallocated_objects += emptymag->rounds;
800 spin_unlock_wr(&depot->spin);
803 emptymag = mag_alloc(depot->magcapacity);
807 if (MAGAZINE_EMPTY(emptymag)) {
808 mag_purge(oc, emptymag, TRUE);
810 spin_lock_wr(&depot->spin);
811 SLIST_INSERT_HEAD(&depot->fullmagazines, emptymag,
813 depot->unallocated_objects += emptymag->rounds;
814 spin_unlock_wr(&depot->spin);
817 emptymag = mag_alloc(depot->magcapacity);
824 * Check depot contention once a minute.
825 * 2 contested locks per second allowed.
827 static int objcache_rebalance_period;
828 static const int objcache_contention_rate = 120;
829 static struct callout objcache_callout;
831 #define MAXMAGSIZE 512
834 * Check depot contention and increase magazine size if necessary.
837 objcache_timer(void *dummy)
840 struct magazinedepot *depot;
841 struct magazinelist tmplist;
843 XXX we need to detect when an objcache is destroyed out from under
846 SLIST_INIT(&tmplist);
848 spin_lock_wr(&objcachelist_spin);
849 SLIST_FOREACH(oc, &allobjcaches, oc_next) {
850 depot = &oc->depot[myclusterid];
851 if (depot->magcapacity < MAXMAGSIZE) {
852 if (depot->contested > objcache_contention_rate) {
853 spin_lock_wr(&depot->spin);
854 depot_disassociate(depot, &tmplist);
855 depot->magcapacity *= 2;
856 spin_unlock_wr(&depot->spin);
857 printf("objcache_timer: increasing cache %s"
858 " magsize to %d, contested %d times\n",
859 oc->name, depot->magcapacity,
862 depot->contested = 0;
864 spin_unlock_wr(&objcachelist_spin);
865 if (maglist_purge(oc, &tmplist) > 0 && depot->waiting)
867 spin_lock_wr(&objcachelist_spin);
869 spin_unlock_wr(&objcachelist_spin);
871 callout_reset(&objcache_callout, objcache_rebalance_period,
872 objcache_timer, NULL);
880 spin_init(&objcachelist_spin);
882 callout_init(&objcache_callout);
883 objcache_rebalance_period = 60 * hz;
884 callout_reset(&objcache_callout, objcache_rebalance_period,
885 objcache_timer, NULL);
888 SYSINIT(objcache, SI_SUB_CPU, SI_ORDER_ANY, objcache_init, 0);