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zfs/module/spl/spl-kmem.c

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/*
* This file is part of the SPL: Solaris Porting Layer.
*
* Copyright (c) 2008 Lawrence Livermore National Security, LLC.
* Produced at Lawrence Livermore National Laboratory
* Written by:
* Brian Behlendorf <behlendorf1@llnl.gov>,
* Herb Wartens <wartens2@llnl.gov>,
* Jim Garlick <garlick@llnl.gov>
* UCRL-CODE-235197
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <sys/kmem.h>
#ifdef DEBUG_SUBSYSTEM
# undef DEBUG_SUBSYSTEM
#endif
#define DEBUG_SUBSYSTEM S_KMEM
/*
* Memory allocation interfaces and debugging for basic kmem_*
* and vmem_* style memory allocation. When DEBUG_KMEM is enable
* all allocations will be tracked when they are allocated and
* freed. When the SPL module is unload a list of all leaked
* addresses and where they were allocated will be dumped to the
* console. Enabling this feature has a significant impant on
* performance but it makes finding memory leaks staight forward.
*/
#ifdef DEBUG_KMEM
/* Shim layer memory accounting */
atomic64_t kmem_alloc_used = ATOMIC64_INIT(0);
unsigned long long kmem_alloc_max = 0;
atomic64_t vmem_alloc_used = ATOMIC64_INIT(0);
unsigned long long vmem_alloc_max = 0;
int kmem_warning_flag = 1;
EXPORT_SYMBOL(kmem_alloc_used);
EXPORT_SYMBOL(kmem_alloc_max);
EXPORT_SYMBOL(vmem_alloc_used);
EXPORT_SYMBOL(vmem_alloc_max);
EXPORT_SYMBOL(kmem_warning_flag);
# ifdef DEBUG_KMEM_TRACKING
/* XXX - Not to surprisingly with debugging enabled the xmem_locks are very
* highly contended particularly on xfree(). If we want to run with this
* detailed debugging enabled for anything other than debugging we need to
* minimize the contention by moving to a lock per xmem_table entry model.
*/
# define KMEM_HASH_BITS 10
# define KMEM_TABLE_SIZE (1 << KMEM_HASH_BITS)
# define VMEM_HASH_BITS 10
# define VMEM_TABLE_SIZE (1 << VMEM_HASH_BITS)
typedef struct kmem_debug {
struct hlist_node kd_hlist; /* Hash node linkage */
struct list_head kd_list; /* List of all allocations */
void *kd_addr; /* Allocation pointer */
size_t kd_size; /* Allocation size */
const char *kd_func; /* Allocation function */
int kd_line; /* Allocation line */
} kmem_debug_t;
spinlock_t kmem_lock;
struct hlist_head kmem_table[KMEM_TABLE_SIZE];
struct list_head kmem_list;
spinlock_t vmem_lock;
struct hlist_head vmem_table[VMEM_TABLE_SIZE];
struct list_head vmem_list;
EXPORT_SYMBOL(kmem_lock);
EXPORT_SYMBOL(kmem_table);
EXPORT_SYMBOL(kmem_list);
EXPORT_SYMBOL(vmem_lock);
EXPORT_SYMBOL(vmem_table);
EXPORT_SYMBOL(vmem_list);
# endif
int kmem_set_warning(int flag) { return (kmem_warning_flag = !!flag); }
#else
int kmem_set_warning(int flag) { return 0; }
#endif
EXPORT_SYMBOL(kmem_set_warning);
/*
* Slab allocation interfaces
*
* While the Linux slab implementation was inspired by the Solaris
* implemenation I cannot use it to emulate the Solaris APIs. I
* require two features which are not provided by the Linux slab.
*
* 1) Constructors AND destructors. Recent versions of the Linux
* kernel have removed support for destructors. This is a deal
* breaker for the SPL which contains particularly expensive
* initializers for mutex's, condition variables, etc. We also
* require a minimal level of cleanup for these data types unlike
* many Linux data type which do need to be explicitly destroyed.
*
* 2) Virtual address space backed slab. Callers of the Solaris slab
* expect it to work well for both small are very large allocations.
* Because of memory fragmentation the Linux slab which is backed
* by kmalloc'ed memory performs very badly when confronted with
* large numbers of large allocations. Basing the slab on the
* virtual address space removes the need for contigeous pages
* and greatly improve performance for large allocations.
*
* For these reasons, the SPL has its own slab implementation with
* the needed features. It is not as highly optimized as either the
* Solaris or Linux slabs, but it should get me most of what is
* needed until it can be optimized or obsoleted by another approach.
*
* One serious concern I do have about this method is the relatively
* small virtual address space on 32bit arches. This will seriously
* constrain the size of the slab caches and their performance.
*
* XXX: Improve the partial slab list by carefully maintaining a
* strict ordering of fullest to emptiest slabs based on
* the slab reference count. This gaurentees the when freeing
* slabs back to the system we need only linearly traverse the
* last N slabs in the list to discover all the freeable slabs.
*
* XXX: NUMA awareness for optionally allocating memory close to a
* particular core. This can be adventageous if you know the slab
* object will be short lived and primarily accessed from one core.
*
* XXX: Slab coloring may also yield performance improvements and would
* be desirable to implement.
*/
struct list_head spl_kmem_cache_list; /* List of caches */
struct rw_semaphore spl_kmem_cache_sem; /* Cache list lock */
static int spl_cache_flush(spl_kmem_cache_t *skc,
spl_kmem_magazine_t *skm, int flush);
#ifdef HAVE_SET_SHRINKER
static struct shrinker *spl_kmem_cache_shrinker;
#else
static int spl_kmem_cache_generic_shrinker(int nr_to_scan,
unsigned int gfp_mask);
static struct shrinker spl_kmem_cache_shrinker = {
.shrink = spl_kmem_cache_generic_shrinker,
.seeks = KMC_DEFAULT_SEEKS,
};
#endif
#ifdef DEBUG_KMEM
# ifdef DEBUG_KMEM_TRACKING
static kmem_debug_t *
kmem_del_init(spinlock_t *lock, struct hlist_head *table, int bits,
void *addr)
{
struct hlist_head *head;
struct hlist_node *node;
struct kmem_debug *p;
unsigned long flags;
ENTRY;
spin_lock_irqsave(lock, flags);
head = &table[hash_ptr(addr, bits)];
hlist_for_each_entry_rcu(p, node, head, kd_hlist) {
if (p->kd_addr == addr) {
hlist_del_init(&p->kd_hlist);
list_del_init(&p->kd_list);
spin_unlock_irqrestore(lock, flags);
return p;
}
}
spin_unlock_irqrestore(lock, flags);
RETURN(NULL);
}
void *
kmem_alloc_track(size_t size, int flags, const char *func, int line,
int node_alloc, int node)
{
void *ptr = NULL;
kmem_debug_t *dptr;
unsigned long irq_flags;
ENTRY;
dptr = (kmem_debug_t *) kmalloc(sizeof(kmem_debug_t),
flags & ~__GFP_ZERO);
if (dptr == NULL) {
CWARN("kmem_alloc(%ld, 0x%x) debug failed\n",
sizeof(kmem_debug_t), flags);
} else {
/* Marked unlikely because we should never be doing this,
* we tolerate to up 2 pages but a single page is best. */
if (unlikely((size) > (PAGE_SIZE * 2)) && kmem_warning_flag)
CWARN("Large kmem_alloc(%llu, 0x%x) (%lld/%llu)\n",
(unsigned long long) size, flags,
atomic64_read(&kmem_alloc_used), kmem_alloc_max);
/* We use kstrdup() below because the string pointed to by
* __FUNCTION__ might not be available by the time we want
* to print it since the module might have been unloaded. */
dptr->kd_func = kstrdup(func, flags & ~__GFP_ZERO);
if (unlikely(dptr->kd_func == NULL)) {
kfree(dptr);
CWARN("kstrdup() failed in kmem_alloc(%llu, 0x%x) "
"(%lld/%llu)\n", (unsigned long long) size, flags,
atomic64_read(&kmem_alloc_used), kmem_alloc_max);
goto out;
}
/* Use the correct allocator */
if (node_alloc) {
ASSERT(!(flags & __GFP_ZERO));
ptr = kmalloc_node(size, flags, node);
} else if (flags & __GFP_ZERO) {
ptr = kzalloc(size, flags & ~__GFP_ZERO);
} else {
ptr = kmalloc(size, flags);
}
if (unlikely(ptr == NULL)) {
kfree(dptr->kd_func);
kfree(dptr);
CWARN("kmem_alloc(%llu, 0x%x) failed (%lld/%llu)\n",
(unsigned long long) size, flags,
atomic64_read(&kmem_alloc_used), kmem_alloc_max);
goto out;
}
atomic64_add(size, &kmem_alloc_used);
if (unlikely(atomic64_read(&kmem_alloc_used) >
kmem_alloc_max))
kmem_alloc_max =
atomic64_read(&kmem_alloc_used);
INIT_HLIST_NODE(&dptr->kd_hlist);
INIT_LIST_HEAD(&dptr->kd_list);
dptr->kd_addr = ptr;
dptr->kd_size = size;
dptr->kd_line = line;
spin_lock_irqsave(&kmem_lock, irq_flags);
hlist_add_head_rcu(&dptr->kd_hlist,
&kmem_table[hash_ptr(ptr, KMEM_HASH_BITS)]);
list_add_tail(&dptr->kd_list, &kmem_list);
spin_unlock_irqrestore(&kmem_lock, irq_flags);
CDEBUG_LIMIT(D_INFO, "kmem_alloc(%llu, 0x%x) = %p "
"(%lld/%llu)\n", (unsigned long long) size, flags,
ptr, atomic64_read(&kmem_alloc_used),
kmem_alloc_max);
}
out:
RETURN(ptr);
}
EXPORT_SYMBOL(kmem_alloc_track);
void
kmem_free_track(void *ptr, size_t size)
{
kmem_debug_t *dptr;
ENTRY;
ASSERTF(ptr || size > 0, "ptr: %p, size: %llu", ptr,
(unsigned long long) size);
dptr = kmem_del_init(&kmem_lock, kmem_table, KMEM_HASH_BITS, ptr);
ASSERT(dptr); /* Must exist in hash due to kmem_alloc() */
/* Size must match */
ASSERTF(dptr->kd_size == size, "kd_size (%llu) != size (%llu), "
"kd_func = %s, kd_line = %d\n", (unsigned long long) dptr->kd_size,
(unsigned long long) size, dptr->kd_func, dptr->kd_line);
atomic64_sub(size, &kmem_alloc_used);
CDEBUG_LIMIT(D_INFO, "kmem_free(%p, %llu) (%lld/%llu)\n", ptr,
(unsigned long long) size, atomic64_read(&kmem_alloc_used),
kmem_alloc_max);
kfree(dptr->kd_func);
memset(dptr, 0x5a, sizeof(kmem_debug_t));
kfree(dptr);
memset(ptr, 0x5a, size);
kfree(ptr);
EXIT;
}
EXPORT_SYMBOL(kmem_free_track);
void *
vmem_alloc_track(size_t size, int flags, const char *func, int line)
{
void *ptr = NULL;
kmem_debug_t *dptr;
unsigned long irq_flags;
ENTRY;
ASSERT(flags & KM_SLEEP);
dptr = (kmem_debug_t *) kmalloc(sizeof(kmem_debug_t), flags);
if (dptr == NULL) {
CWARN("vmem_alloc(%ld, 0x%x) debug failed\n",
sizeof(kmem_debug_t), flags);
} else {
/* We use kstrdup() below because the string pointed to by
* __FUNCTION__ might not be available by the time we want
* to print it, since the module might have been unloaded. */
dptr->kd_func = kstrdup(func, flags & ~__GFP_ZERO);
if (unlikely(dptr->kd_func == NULL)) {
kfree(dptr);
CWARN("kstrdup() failed in vmem_alloc(%llu, 0x%x) "
"(%lld/%llu)\n", (unsigned long long) size, flags,
atomic64_read(&vmem_alloc_used), vmem_alloc_max);
goto out;
}
ptr = __vmalloc(size, (flags | __GFP_HIGHMEM) & ~__GFP_ZERO,
PAGE_KERNEL);
if (unlikely(ptr == NULL)) {
kfree(dptr->kd_func);
kfree(dptr);
CWARN("vmem_alloc(%llu, 0x%x) failed (%lld/%llu)\n",
(unsigned long long) size, flags,
atomic64_read(&vmem_alloc_used), vmem_alloc_max);
goto out;
}
if (flags & __GFP_ZERO)
memset(ptr, 0, size);
atomic64_add(size, &vmem_alloc_used);
if (unlikely(atomic64_read(&vmem_alloc_used) >
vmem_alloc_max))
vmem_alloc_max =
atomic64_read(&vmem_alloc_used);
INIT_HLIST_NODE(&dptr->kd_hlist);
INIT_LIST_HEAD(&dptr->kd_list);
dptr->kd_addr = ptr;
dptr->kd_size = size;
dptr->kd_line = line;
spin_lock_irqsave(&vmem_lock, irq_flags);
hlist_add_head_rcu(&dptr->kd_hlist,
&vmem_table[hash_ptr(ptr, VMEM_HASH_BITS)]);
list_add_tail(&dptr->kd_list, &vmem_list);
spin_unlock_irqrestore(&vmem_lock, irq_flags);
CDEBUG_LIMIT(D_INFO, "vmem_alloc(%llu, 0x%x) = %p "
"(%lld/%llu)\n", (unsigned long long) size, flags,
ptr, atomic64_read(&vmem_alloc_used),
vmem_alloc_max);
}
out:
RETURN(ptr);
}
EXPORT_SYMBOL(vmem_alloc_track);
void
vmem_free_track(void *ptr, size_t size)
{
kmem_debug_t *dptr;
ENTRY;
ASSERTF(ptr || size > 0, "ptr: %p, size: %llu", ptr,
(unsigned long long) size);
dptr = kmem_del_init(&vmem_lock, vmem_table, VMEM_HASH_BITS, ptr);
ASSERT(dptr); /* Must exist in hash due to vmem_alloc() */
/* Size must match */
ASSERTF(dptr->kd_size == size, "kd_size (%llu) != size (%llu), "
"kd_func = %s, kd_line = %d\n", (unsigned long long) dptr->kd_size,
(unsigned long long) size, dptr->kd_func, dptr->kd_line);
atomic64_sub(size, &vmem_alloc_used);
CDEBUG_LIMIT(D_INFO, "vmem_free(%p, %llu) (%lld/%llu)\n", ptr,
(unsigned long long) size, atomic64_read(&vmem_alloc_used),
vmem_alloc_max);
kfree(dptr->kd_func);
memset(dptr, 0x5a, sizeof(kmem_debug_t));
kfree(dptr);
memset(ptr, 0x5a, size);
vfree(ptr);
EXIT;
}
EXPORT_SYMBOL(vmem_free_track);
# else /* DEBUG_KMEM_TRACKING */
void *
kmem_alloc_debug(size_t size, int flags, const char *func, int line,
int node_alloc, int node)
{
void *ptr;
ENTRY;
/* Marked unlikely because we should never be doing this,
* we tolerate to up 2 pages but a single page is best. */
if (unlikely(size > (PAGE_SIZE * 2)) && kmem_warning_flag)
CWARN("Large kmem_alloc(%llu, 0x%x) (%lld/%llu)\n",
(unsigned long long) size, flags,
atomic64_read(&kmem_alloc_used), kmem_alloc_max);
/* Use the correct allocator */
if (node_alloc) {
ASSERT(!(flags & __GFP_ZERO));
ptr = kmalloc_node(size, flags, node);
} else if (flags & __GFP_ZERO) {
ptr = kzalloc(size, flags & (~__GFP_ZERO));
} else {
ptr = kmalloc(size, flags);
}
if (ptr == NULL) {
CWARN("kmem_alloc(%llu, 0x%x) failed (%lld/%llu)\n",
(unsigned long long) size, flags,
atomic64_read(&kmem_alloc_used), kmem_alloc_max);
} else {
atomic64_add(size, &kmem_alloc_used);
if (unlikely(atomic64_read(&kmem_alloc_used) > kmem_alloc_max))
kmem_alloc_max = atomic64_read(&kmem_alloc_used);
CDEBUG_LIMIT(D_INFO, "kmem_alloc(%llu, 0x%x) = %p "
"(%lld/%llu)\n", (unsigned long long) size, flags, ptr,
atomic64_read(&kmem_alloc_used), kmem_alloc_max);
}
RETURN(ptr);
}
EXPORT_SYMBOL(kmem_alloc_debug);
void
kmem_free_debug(void *ptr, size_t size)
{
ENTRY;
ASSERTF(ptr || size > 0, "ptr: %p, size: %llu", ptr,
(unsigned long long) size);
atomic64_sub(size, &kmem_alloc_used);
CDEBUG_LIMIT(D_INFO, "kmem_free(%p, %llu) (%lld/%llu)\n", ptr,
(unsigned long long) size, atomic64_read(&kmem_alloc_used),
kmem_alloc_max);
memset(ptr, 0x5a, size);
kfree(ptr);
EXIT;
}
EXPORT_SYMBOL(kmem_free_debug);
void *
vmem_alloc_debug(size_t size, int flags, const char *func, int line)
{
void *ptr;
ENTRY;
ASSERT(flags & KM_SLEEP);
ptr = __vmalloc(size, (flags | __GFP_HIGHMEM) & ~__GFP_ZERO,
PAGE_KERNEL);
if (ptr == NULL) {
CWARN("vmem_alloc(%llu, 0x%x) failed (%lld/%llu)\n",
(unsigned long long) size, flags,
atomic64_read(&vmem_alloc_used), vmem_alloc_max);
} else {
if (flags & __GFP_ZERO)
memset(ptr, 0, size);
atomic64_add(size, &vmem_alloc_used);
if (unlikely(atomic64_read(&vmem_alloc_used) > vmem_alloc_max))
vmem_alloc_max = atomic64_read(&vmem_alloc_used);
CDEBUG_LIMIT(D_INFO, "vmem_alloc(%llu, 0x%x) = %p "
"(%lld/%llu)\n", (unsigned long long) size, flags, ptr,
atomic64_read(&vmem_alloc_used), vmem_alloc_max);
}
RETURN(ptr);
}
EXPORT_SYMBOL(vmem_alloc_debug);
void
vmem_free_debug(void *ptr, size_t size)
{
ENTRY;
ASSERTF(ptr || size > 0, "ptr: %p, size: %llu", ptr,
(unsigned long long) size);
atomic64_sub(size, &vmem_alloc_used);
CDEBUG_LIMIT(D_INFO, "vmem_free(%p, %llu) (%lld/%llu)\n", ptr,
(unsigned long long) size, atomic64_read(&vmem_alloc_used),
vmem_alloc_max);
memset(ptr, 0x5a, size);
vfree(ptr);
EXIT;
}
EXPORT_SYMBOL(vmem_free_debug);
# endif /* DEBUG_KMEM_TRACKING */
#endif /* DEBUG_KMEM */
static void *
kv_alloc(spl_kmem_cache_t *skc, int size, int flags)
{
void *ptr;
if (skc->skc_flags & KMC_KMEM) {
if (size > (2 * PAGE_SIZE)) {
ptr = (void *)__get_free_pages(flags, get_order(size));
} else
ptr = kmem_alloc(size, flags);
} else {
ptr = vmem_alloc(size, flags);
}
return ptr;
}
static void
kv_free(spl_kmem_cache_t *skc, void *ptr, int size)
{
if (skc->skc_flags & KMC_KMEM) {
if (size > (2 * PAGE_SIZE))
free_pages((unsigned long)ptr, get_order(size));
else
kmem_free(ptr, size);
} else {
vmem_free(ptr, size);
}
}
/*
* It's important that we pack the spl_kmem_obj_t structure and the
* actual objects in to one large address space to minimize the number
* of calls to the allocator. It is far better to do a few large
* allocations and then subdivide it ourselves. Now which allocator
* we use requires balancing a few trade offs.
*
* For small objects we use kmem_alloc() because as long as you are
* only requesting a small number of pages (ideally just one) its cheap.
* However, when you start requesting multiple pages with kmem_alloc()
* it gets increasingly expensive since it requires contigeous pages.
* For this reason we shift to vmem_alloc() for slabs of large objects
* which removes the need for contigeous pages. We do not use
* vmem_alloc() in all cases because there is significant locking
* overhead in __get_vm_area_node(). This function takes a single
* global lock when aquiring an available virtual address range which
* serializes all vmem_alloc()'s for all slab caches. Using slightly
* different allocation functions for small and large objects should
* give us the best of both worlds.
*
* KMC_ONSLAB KMC_OFFSLAB
*
* +------------------------+ +-----------------+
* | spl_kmem_slab_t --+-+ | | spl_kmem_slab_t |---+-+
* | skc_obj_size <-+ | | +-----------------+ | |
* | spl_kmem_obj_t | | | |
* | skc_obj_size <---+ | +-----------------+ | |
* | spl_kmem_obj_t | | | skc_obj_size | <-+ |
* | ... v | | spl_kmem_obj_t | |
* +------------------------+ +-----------------+ v
*/
static spl_kmem_slab_t *
spl_slab_alloc(spl_kmem_cache_t *skc, int flags)
{
spl_kmem_slab_t *sks;
spl_kmem_obj_t *sko, *n;
void *base, *obj;
int i, align, size, rc = 0;
base = kv_alloc(skc, skc->skc_slab_size, flags);
if (base == NULL)
RETURN(NULL);
sks = (spl_kmem_slab_t *)base;
sks->sks_magic = SKS_MAGIC;
sks->sks_objs = skc->skc_slab_objs;
sks->sks_age = jiffies;
sks->sks_cache = skc;
INIT_LIST_HEAD(&sks->sks_list);
INIT_LIST_HEAD(&sks->sks_free_list);
sks->sks_ref = 0;
align = skc->skc_obj_align;
size = P2ROUNDUP(skc->skc_obj_size, align) +
P2ROUNDUP(sizeof(spl_kmem_obj_t), align);
for (i = 0; i < sks->sks_objs; i++) {
if (skc->skc_flags & KMC_OFFSLAB) {
obj = kv_alloc(skc, size, flags);
if (!obj)
GOTO(out, rc = -ENOMEM);
} else {
obj = base +
P2ROUNDUP(sizeof(spl_kmem_slab_t), align) +
(i * size);
}
sko = obj + P2ROUNDUP(skc->skc_obj_size, align);
sko->sko_addr = obj;
sko->sko_magic = SKO_MAGIC;
sko->sko_slab = sks;
INIT_LIST_HEAD(&sko->sko_list);
list_add_tail(&sko->sko_list, &sks->sks_free_list);
}
list_for_each_entry(sko, &sks->sks_free_list, sko_list)
if (skc->skc_ctor)
skc->skc_ctor(sko->sko_addr, skc->skc_private, flags);
out:
if (rc) {
if (skc->skc_flags & KMC_OFFSLAB)
list_for_each_entry_safe(sko, n, &sks->sks_free_list,
sko_list)
kv_free(skc, sko->sko_addr, size);
kv_free(skc, base, skc->skc_slab_size);
sks = NULL;
}
RETURN(sks);
}
/*
* Remove a slab from complete or partial list, it must be called with
* the 'skc->skc_lock' held but the actual free must be performed
* outside the lock to prevent deadlocking on vmem addresses.
*/
static void
spl_slab_free(spl_kmem_slab_t *sks,
struct list_head *sks_list, struct list_head *sko_list)
{
spl_kmem_cache_t *skc;
spl_kmem_obj_t *sko, *n;
ENTRY;
ASSERT(sks->sks_magic == SKS_MAGIC);
ASSERT(sks->sks_ref == 0);
skc = sks->sks_cache;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(spin_is_locked(&skc->skc_lock));
skc->skc_obj_total -= sks->sks_objs;
skc->skc_slab_total--;
list_del(&sks->sks_list);
/* Run destructors slab is being released */
list_for_each_entry_safe(sko, n, &sks->sks_free_list, sko_list) {
ASSERT(sko->sko_magic == SKO_MAGIC);
list_del(&sko->sko_list);
if (skc->skc_dtor)
skc->skc_dtor(sko->sko_addr, skc->skc_private);
if (skc->skc_flags & KMC_OFFSLAB)
list_add(&sko->sko_list, sko_list);
}
list_add(&sks->sks_list, sks_list);
EXIT;
}
/*
* Traverses all the partial slabs attached to a cache and free those
* which which are currently empty, and have not been touched for
* skc_delay seconds. This is to avoid thrashing.
*/
static void
spl_slab_reclaim(spl_kmem_cache_t *skc, int flag)
{
spl_kmem_slab_t *sks, *m;
spl_kmem_obj_t *sko, *n;
LIST_HEAD(sks_list);
LIST_HEAD(sko_list);
int size;
ENTRY;
/*
* Move empty slabs and objects which have not been touched in
* skc_delay seconds on to private lists to be freed outside
* the spin lock. This delay time is important to avoid
* thrashing however when flag is set the delay will not be
* used. Empty slabs will be at the end of the skc_partial_list.
*/
spin_lock(&skc->skc_lock);
list_for_each_entry_safe_reverse(sks, m, &skc->skc_partial_list,
sks_list) {
if (sks->sks_ref > 0)
break;
if (flag || time_after(jiffies,sks->sks_age+skc->skc_delay*HZ))
spl_slab_free(sks, &sks_list, &sko_list);
}
spin_unlock(&skc->skc_lock);
/*
* We only have list of spl_kmem_obj_t's if they are located off
* the slab, otherwise they get feed with the spl_kmem_slab_t.
*/
if (!list_empty(&sko_list)) {
ASSERT(skc->skc_flags & KMC_OFFSLAB);
size = P2ROUNDUP(skc->skc_obj_size, skc->skc_obj_align) +
P2ROUNDUP(sizeof(spl_kmem_obj_t), skc->skc_obj_align);
list_for_each_entry_safe(sko, n, &sko_list, sko_list)
kv_free(skc, sko->sko_addr, size);
}
list_for_each_entry_safe(sks, m, &sks_list, sks_list)
kv_free(skc, sks, skc->skc_slab_size);
EXIT;
}
/*
* Called regularly on all caches to age objects out of the magazines
* which have not been access in skc->skc_delay seconds. This prevents
* idle magazines from holding memory which might be better used by
* other caches or parts of the system. The delay is present to
* prevent thrashing the magazine.
*/
static void
spl_magazine_age(void *data)
{
spl_kmem_cache_t *skc = data;
spl_kmem_magazine_t *skm = skc->skc_mag[smp_processor_id()];
if (skm->skm_avail > 0 &&
time_after(jiffies, skm->skm_age + skc->skc_delay * HZ))
(void)spl_cache_flush(skc, skm, skm->skm_refill);
}
/*
* Called regularly to keep a downward pressure on the size of idle
* magazines and to release free slabs from the cache. This function
* never calls the registered reclaim function, that only occures
* under memory pressure or with a direct call to spl_kmem_reap().
*/
static void
spl_cache_age(void *data)
{
spl_kmem_cache_t *skc =
spl_get_work_data(data, spl_kmem_cache_t, skc_work.work);
ASSERT(skc->skc_magic == SKC_MAGIC);
spl_on_each_cpu(spl_magazine_age, skc, 1);
spl_slab_reclaim(skc, 0);
if (!test_bit(KMC_BIT_DESTROY, &skc->skc_flags))
schedule_delayed_work(&skc->skc_work, 2 * skc->skc_delay * HZ);
}
/*
* Size a slab based on the size of each aliged object plus spl_kmem_obj_t.
* When on-slab we want to target SPL_KMEM_CACHE_OBJ_PER_SLAB. However,
* for very small objects we may end up with more than this so as not
* to waste space in the minimal allocation of a single page. Also for
* very large objects we may use as few as SPL_KMEM_CACHE_OBJ_PER_SLAB_MIN,
* lower than this and we will fail.
*/
static int
spl_slab_size(spl_kmem_cache_t *skc, uint32_t *objs, uint32_t *size)
{
int sks_size, obj_size, max_size, align;
if (skc->skc_flags & KMC_OFFSLAB) {
*objs = SPL_KMEM_CACHE_OBJ_PER_SLAB;
*size = sizeof(spl_kmem_slab_t);
} else {
align = skc->skc_obj_align;
sks_size = P2ROUNDUP(sizeof(spl_kmem_slab_t), align);
obj_size = P2ROUNDUP(skc->skc_obj_size, align) +
P2ROUNDUP(sizeof(spl_kmem_obj_t), align);
if (skc->skc_flags & KMC_KMEM)
max_size = ((uint64_t)1 << (MAX_ORDER-1)) * PAGE_SIZE;
else
max_size = (32 * 1024 * 1024);
for (*size = PAGE_SIZE; *size <= max_size; *size += PAGE_SIZE) {
*objs = (*size - sks_size) / obj_size;
if (*objs >= SPL_KMEM_CACHE_OBJ_PER_SLAB)
RETURN(0);
}
/*
* Unable to satisfy target objets per slab, fallback to
* allocating a maximally sized slab and assuming it can
* contain the minimum objects count use it. If not fail.
*/
*size = max_size;
*objs = (*size - sks_size) / obj_size;
if (*objs >= SPL_KMEM_CACHE_OBJ_PER_SLAB_MIN)
RETURN(0);
}
RETURN(-ENOSPC);
}
/*
* Make a guess at reasonable per-cpu magazine size based on the size of
* each object and the cost of caching N of them in each magazine. Long
* term this should really adapt based on an observed usage heuristic.
*/
static int
spl_magazine_size(spl_kmem_cache_t *skc)
{
int size, align = skc->skc_obj_align;
ENTRY;
/* Per-magazine sizes below assume a 4Kib page size */
if (P2ROUNDUP(skc->skc_obj_size, align) > (PAGE_SIZE * 256))
size = 4; /* Minimum 4Mib per-magazine */
else if (P2ROUNDUP(skc->skc_obj_size, align) > (PAGE_SIZE * 32))
size = 16; /* Minimum 2Mib per-magazine */
else if (P2ROUNDUP(skc->skc_obj_size, align) > (PAGE_SIZE))
size = 64; /* Minimum 256Kib per-magazine */
else if (P2ROUNDUP(skc->skc_obj_size, align) > (PAGE_SIZE / 4))
size = 128; /* Minimum 128Kib per-magazine */
else
size = 256;
RETURN(size);
}
/*
* Allocate a per-cpu magazine to assoicate with a specific core.
*/
static spl_kmem_magazine_t *
spl_magazine_alloc(spl_kmem_cache_t *skc, int node)
{
spl_kmem_magazine_t *skm;
int size = sizeof(spl_kmem_magazine_t) +
sizeof(void *) * skc->skc_mag_size;
ENTRY;
skm = kmem_alloc_node(size, GFP_KERNEL | __GFP_NOFAIL, node);
if (skm) {
skm->skm_magic = SKM_MAGIC;
skm->skm_avail = 0;
skm->skm_size = skc->skc_mag_size;
skm->skm_refill = skc->skc_mag_refill;
skm->skm_age = jiffies;
}
RETURN(skm);
}
/*
* Free a per-cpu magazine assoicated with a specific core.
*/
static void
spl_magazine_free(spl_kmem_magazine_t *skm)
{
int size = sizeof(spl_kmem_magazine_t) +
sizeof(void *) * skm->skm_size;
ENTRY;
ASSERT(skm->skm_magic == SKM_MAGIC);
ASSERT(skm->skm_avail == 0);
kmem_free(skm, size);
EXIT;
}
static void
__spl_magazine_create(void *data)
{
spl_kmem_cache_t *skc = data;
int id = smp_processor_id();
skc->skc_mag[id] = spl_magazine_alloc(skc, cpu_to_node(id));
ASSERT(skc->skc_mag[id]);
}
/*
* Create all pre-cpu magazines of reasonable sizes.
*/
static int
spl_magazine_create(spl_kmem_cache_t *skc)
{
ENTRY;
skc->skc_mag_size = spl_magazine_size(skc);
skc->skc_mag_refill = (skc->skc_mag_size + 1) / 2;
spl_on_each_cpu(__spl_magazine_create, skc, 1);
RETURN(0);
}
static void
__spl_magazine_destroy(void *data)
{
spl_kmem_cache_t *skc = data;
spl_kmem_magazine_t *skm = skc->skc_mag[smp_processor_id()];
(void)spl_cache_flush(skc, skm, skm->skm_avail);
spl_magazine_free(skm);
}
/*
* Destroy all pre-cpu magazines.
*/
static void
spl_magazine_destroy(spl_kmem_cache_t *skc)
{
ENTRY;
spl_on_each_cpu(__spl_magazine_destroy, skc, 1);
EXIT;
}
/*
* Create a object cache based on the following arguments:
* name cache name
* size cache object size
* align cache object alignment
* ctor cache object constructor
* dtor cache object destructor
* reclaim cache object reclaim
* priv cache private data for ctor/dtor/reclaim
* vmp unused must be NULL
* flags
* KMC_NOTOUCH Disable cache object aging (unsupported)
* KMC_NODEBUG Disable debugging (unsupported)
* KMC_NOMAGAZINE Disable magazine (unsupported)
* KMC_NOHASH Disable hashing (unsupported)
* KMC_QCACHE Disable qcache (unsupported)
* KMC_KMEM Force kmem backed cache
* KMC_VMEM Force vmem backed cache
* KMC_OFFSLAB Locate objects off the slab
*/
spl_kmem_cache_t *
spl_kmem_cache_create(char *name, size_t size, size_t align,
spl_kmem_ctor_t ctor,
spl_kmem_dtor_t dtor,
spl_kmem_reclaim_t reclaim,
void *priv, void *vmp, int flags)
{
spl_kmem_cache_t *skc;
int rc, kmem_flags = KM_SLEEP;
ENTRY;
ASSERTF(!(flags & KMC_NOMAGAZINE), "Bad KMC_NOMAGAZINE (%x)\n", flags);
ASSERTF(!(flags & KMC_NOHASH), "Bad KMC_NOHASH (%x)\n", flags);
ASSERTF(!(flags & KMC_QCACHE), "Bad KMC_QCACHE (%x)\n", flags);
ASSERT(vmp == NULL);
/* We may be called when there is a non-zero preempt_count or
* interrupts are disabled is which case we must not sleep.
*/
if (current_thread_info()->preempt_count || irqs_disabled())
kmem_flags = KM_NOSLEEP;
/* Allocate new cache memory and initialize. */
skc = (spl_kmem_cache_t *)kmem_zalloc(sizeof(*skc), kmem_flags);
if (skc == NULL)
RETURN(NULL);
skc->skc_magic = SKC_MAGIC;
skc->skc_name_size = strlen(name) + 1;
skc->skc_name = (char *)kmem_alloc(skc->skc_name_size, kmem_flags);
if (skc->skc_name == NULL) {
kmem_free(skc, sizeof(*skc));
RETURN(NULL);
}
strncpy(skc->skc_name, name, skc->skc_name_size);
skc->skc_ctor = ctor;
skc->skc_dtor = dtor;
skc->skc_reclaim = reclaim;
skc->skc_private = priv;
skc->skc_vmp = vmp;
skc->skc_flags = flags;
skc->skc_obj_size = size;
skc->skc_obj_align = SPL_KMEM_CACHE_ALIGN;
skc->skc_delay = SPL_KMEM_CACHE_DELAY;
atomic_set(&skc->skc_ref, 0);
INIT_LIST_HEAD(&skc->skc_list);
INIT_LIST_HEAD(&skc->skc_complete_list);
INIT_LIST_HEAD(&skc->skc_partial_list);
spin_lock_init(&skc->skc_lock);
skc->skc_slab_fail = 0;
skc->skc_slab_create = 0;
skc->skc_slab_destroy = 0;
skc->skc_slab_total = 0;
skc->skc_slab_alloc = 0;
skc->skc_slab_max = 0;
skc->skc_obj_total = 0;
skc->skc_obj_alloc = 0;
skc->skc_obj_max = 0;
if (align) {
ASSERT((align & (align - 1)) == 0); /* Power of two */
ASSERT(align >= SPL_KMEM_CACHE_ALIGN); /* Minimum size */
skc->skc_obj_align = align;
}
/* If none passed select a cache type based on object size */
if (!(skc->skc_flags & (KMC_KMEM | KMC_VMEM))) {
if (P2ROUNDUP(skc->skc_obj_size, skc->skc_obj_align) <
(PAGE_SIZE / 8)) {
skc->skc_flags |= KMC_KMEM;
} else {
skc->skc_flags |= KMC_VMEM;
}
}
rc = spl_slab_size(skc, &skc->skc_slab_objs, &skc->skc_slab_size);
if (rc)
GOTO(out, rc);
rc = spl_magazine_create(skc);
if (rc)
GOTO(out, rc);
spl_init_delayed_work(&skc->skc_work, spl_cache_age, skc);
schedule_delayed_work(&skc->skc_work, 2 * skc->skc_delay * HZ);
down_write(&spl_kmem_cache_sem);
list_add_tail(&skc->skc_list, &spl_kmem_cache_list);
up_write(&spl_kmem_cache_sem);
RETURN(skc);
out:
kmem_free(skc->skc_name, skc->skc_name_size);
kmem_free(skc, sizeof(*skc));
RETURN(NULL);
}
EXPORT_SYMBOL(spl_kmem_cache_create);
/*
* Destroy a cache and all objects assoicated with the cache.
*/
void
spl_kmem_cache_destroy(spl_kmem_cache_t *skc)
{
DECLARE_WAIT_QUEUE_HEAD(wq);
ENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
down_write(&spl_kmem_cache_sem);
list_del_init(&skc->skc_list);
up_write(&spl_kmem_cache_sem);
/* Cancel any and wait for any pending delayed work */
ASSERT(!test_and_set_bit(KMC_BIT_DESTROY, &skc->skc_flags));
cancel_delayed_work(&skc->skc_work);
flush_scheduled_work();
/* Wait until all current callers complete, this is mainly
* to catch the case where a low memory situation triggers a
* cache reaping action which races with this destroy. */
wait_event(wq, atomic_read(&skc->skc_ref) == 0);
spl_magazine_destroy(skc);
spl_slab_reclaim(skc, 1);
spin_lock(&skc->skc_lock);
/* Validate there are no objects in use and free all the
* spl_kmem_slab_t, spl_kmem_obj_t, and object buffers. */
ASSERT3U(skc->skc_slab_alloc, ==, 0);
ASSERT3U(skc->skc_obj_alloc, ==, 0);
ASSERT3U(skc->skc_slab_total, ==, 0);
ASSERT3U(skc->skc_obj_total, ==, 0);
ASSERT(list_empty(&skc->skc_complete_list));
kmem_free(skc->skc_name, skc->skc_name_size);
spin_unlock(&skc->skc_lock);
kmem_free(skc, sizeof(*skc));
EXIT;
}
EXPORT_SYMBOL(spl_kmem_cache_destroy);
/*
* Allocate an object from a slab attached to the cache. This is used to
* repopulate the per-cpu magazine caches in batches when they run low.
*/
static void *
spl_cache_obj(spl_kmem_cache_t *skc, spl_kmem_slab_t *sks)
{
spl_kmem_obj_t *sko;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(sks->sks_magic == SKS_MAGIC);
ASSERT(spin_is_locked(&skc->skc_lock));
sko = list_entry(sks->sks_free_list.next, spl_kmem_obj_t, sko_list);
ASSERT(sko->sko_magic == SKO_MAGIC);
ASSERT(sko->sko_addr != NULL);
/* Remove from sks_free_list */
list_del_init(&sko->sko_list);
sks->sks_age = jiffies;
sks->sks_ref++;
skc->skc_obj_alloc++;
/* Track max obj usage statistics */
if (skc->skc_obj_alloc > skc->skc_obj_max)
skc->skc_obj_max = skc->skc_obj_alloc;
/* Track max slab usage statistics */
if (sks->sks_ref == 1) {
skc->skc_slab_alloc++;
if (skc->skc_slab_alloc > skc->skc_slab_max)
skc->skc_slab_max = skc->skc_slab_alloc;
}
return sko->sko_addr;
}
/*
* No available objects on any slabsi, create a new slab. Since this
* is an expensive operation we do it without holding the spinlock and
* only briefly aquire it when we link in the fully allocated and
* constructed slab.
*/
static spl_kmem_slab_t *
spl_cache_grow(spl_kmem_cache_t *skc, int flags)
{
spl_kmem_slab_t *sks;
ENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
local_irq_enable();
might_sleep();
/*
* Before allocating a new slab check if the slab is being reaped.
* If it is there is a good chance we can wait until it finishes
* and then use one of the newly freed but not aged-out slabs.
*/
if (test_bit(KMC_BIT_REAPING, &skc->skc_flags)) {
schedule();
GOTO(out, sks= NULL);
}
/* Allocate a new slab for the cache */
sks = spl_slab_alloc(skc, flags | __GFP_NORETRY | __GFP_NOWARN);
if (sks == NULL)
GOTO(out, sks = NULL);
/* Link the new empty slab in to the end of skc_partial_list. */
spin_lock(&skc->skc_lock);
skc->skc_slab_total++;
skc->skc_obj_total += sks->sks_objs;
list_add_tail(&sks->sks_list, &skc->skc_partial_list);
spin_unlock(&skc->skc_lock);
out:
local_irq_disable();
RETURN(sks);
}
/*
* Refill a per-cpu magazine with objects from the slabs for this
* cache. Ideally the magazine can be repopulated using existing
* objects which have been released, however if we are unable to
* locate enough free objects new slabs of objects will be created.
*/
static int
spl_cache_refill(spl_kmem_cache_t *skc, spl_kmem_magazine_t *skm, int flags)
{
spl_kmem_slab_t *sks;
int rc = 0, refill;
ENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(skm->skm_magic == SKM_MAGIC);
refill = MIN(skm->skm_refill, skm->skm_size - skm->skm_avail);
spin_lock(&skc->skc_lock);
while (refill > 0) {
/* No slabs available we may need to grow the cache */
if (list_empty(&skc->skc_partial_list)) {
spin_unlock(&skc->skc_lock);
sks = spl_cache_grow(skc, flags);
if (!sks)
GOTO(out, rc);
/* Rescheduled to different CPU skm is not local */
if (skm != skc->skc_mag[smp_processor_id()])
GOTO(out, rc);
/* Potentially rescheduled to the same CPU but
* allocations may have occured from this CPU while
* we were sleeping so recalculate max refill. */
refill = MIN(refill, skm->skm_size - skm->skm_avail);
spin_lock(&skc->skc_lock);
continue;
}
/* Grab the next available slab */
sks = list_entry((&skc->skc_partial_list)->next,
spl_kmem_slab_t, sks_list);
ASSERT(sks->sks_magic == SKS_MAGIC);
ASSERT(sks->sks_ref < sks->sks_objs);
ASSERT(!list_empty(&sks->sks_free_list));
/* Consume as many objects as needed to refill the requested
* cache. We must also be careful not to overfill it. */
while (sks->sks_ref < sks->sks_objs && refill-- > 0 && ++rc) {
ASSERT(skm->skm_avail < skm->skm_size);
ASSERT(rc < skm->skm_size);
skm->skm_objs[skm->skm_avail++]=spl_cache_obj(skc,sks);
}
/* Move slab to skc_complete_list when full */
if (sks->sks_ref == sks->sks_objs) {
list_del(&sks->sks_list);
list_add(&sks->sks_list, &skc->skc_complete_list);
}
}
spin_unlock(&skc->skc_lock);
out:
/* Returns the number of entries added to cache */
RETURN(rc);
}
/*
* Release an object back to the slab from which it came.
*/
static void
spl_cache_shrink(spl_kmem_cache_t *skc, void *obj)
{
spl_kmem_slab_t *sks = NULL;
spl_kmem_obj_t *sko = NULL;
ENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(spin_is_locked(&skc->skc_lock));
sko = obj + P2ROUNDUP(skc->skc_obj_size, skc->skc_obj_align);
ASSERT(sko->sko_magic == SKO_MAGIC);
sks = sko->sko_slab;
ASSERT(sks->sks_magic == SKS_MAGIC);
ASSERT(sks->sks_cache == skc);
list_add(&sko->sko_list, &sks->sks_free_list);
sks->sks_age = jiffies;
sks->sks_ref--;
skc->skc_obj_alloc--;
/* Move slab to skc_partial_list when no longer full. Slabs
* are added to the head to keep the partial list is quasi-full
* sorted order. Fuller at the head, emptier at the tail. */
if (sks->sks_ref == (sks->sks_objs - 1)) {
list_del(&sks->sks_list);
list_add(&sks->sks_list, &skc->skc_partial_list);
}
/* Move emply slabs to the end of the partial list so
* they can be easily found and freed during reclamation. */
if (sks->sks_ref == 0) {
list_del(&sks->sks_list);
list_add_tail(&sks->sks_list, &skc->skc_partial_list);
skc->skc_slab_alloc--;
}
EXIT;
}
/*
* Release a batch of objects from a per-cpu magazine back to their
* respective slabs. This occurs when we exceed the magazine size,
* are under memory pressure, when the cache is idle, or during
* cache cleanup. The flush argument contains the number of entries
* to remove from the magazine.
*/
static int
spl_cache_flush(spl_kmem_cache_t *skc, spl_kmem_magazine_t *skm, int flush)
{
int i, count = MIN(flush, skm->skm_avail);
ENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(skm->skm_magic == SKM_MAGIC);
/*
* XXX: Currently we simply return objects from the magazine to
* the slabs in fifo order. The ideal thing to do from a memory
* fragmentation standpoint is to cheaply determine the set of
* objects in the magazine which will result in the largest
* number of free slabs if released from the magazine.
*/
spin_lock(&skc->skc_lock);
for (i = 0; i < count; i++)
spl_cache_shrink(skc, skm->skm_objs[i]);
skm->skm_avail -= count;
memmove(skm->skm_objs, &(skm->skm_objs[count]),
sizeof(void *) * skm->skm_avail);
spin_unlock(&skc->skc_lock);
RETURN(count);
}
/*
* Allocate an object from the per-cpu magazine, or if the magazine
* is empty directly allocate from a slab and repopulate the magazine.
*/
void *
spl_kmem_cache_alloc(spl_kmem_cache_t *skc, int flags)
{
spl_kmem_magazine_t *skm;
unsigned long irq_flags;
void *obj = NULL;
ENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
ASSERT(flags & KM_SLEEP);
atomic_inc(&skc->skc_ref);
local_irq_save(irq_flags);
restart:
/* Safe to update per-cpu structure without lock, but
* in the restart case we must be careful to reaquire
* the local magazine since this may have changed
* when we need to grow the cache. */
skm = skc->skc_mag[smp_processor_id()];
ASSERTF(skm->skm_magic == SKM_MAGIC, "%x != %x: %s/%p/%p %x/%x/%x\n",
skm->skm_magic, SKM_MAGIC, skc->skc_name, skc, skm,
skm->skm_size, skm->skm_refill, skm->skm_avail);
if (likely(skm->skm_avail)) {
/* Object available in CPU cache, use it */
obj = skm->skm_objs[--skm->skm_avail];
skm->skm_age = jiffies;
} else {
/* Per-CPU cache empty, directly allocate from
* the slab and refill the per-CPU cache. */
(void)spl_cache_refill(skc, skm, flags);
GOTO(restart, obj = NULL);
}
local_irq_restore(irq_flags);
ASSERT(obj);
ASSERT(((unsigned long)(obj) % skc->skc_obj_align) == 0);
/* Pre-emptively migrate object to CPU L1 cache */
prefetchw(obj);
atomic_dec(&skc->skc_ref);
RETURN(obj);
}
EXPORT_SYMBOL(spl_kmem_cache_alloc);
/*
* Free an object back to the local per-cpu magazine, there is no
* guarantee that this is the same magazine the object was originally
* allocated from. We may need to flush entire from the magazine
* back to the slabs to make space.
*/
void
spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj)
{
spl_kmem_magazine_t *skm;
unsigned long flags;
ENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
atomic_inc(&skc->skc_ref);
local_irq_save(flags);
/* Safe to update per-cpu structure without lock, but
* no remote memory allocation tracking is being performed
* it is entirely possible to allocate an object from one
* CPU cache and return it to another. */
skm = skc->skc_mag[smp_processor_id()];
ASSERT(skm->skm_magic == SKM_MAGIC);
/* Per-CPU cache full, flush it to make space */
if (unlikely(skm->skm_avail >= skm->skm_size))
(void)spl_cache_flush(skc, skm, skm->skm_refill);
/* Available space in cache, use it */
skm->skm_objs[skm->skm_avail++] = obj;
local_irq_restore(flags);
atomic_dec(&skc->skc_ref);
EXIT;
}
EXPORT_SYMBOL(spl_kmem_cache_free);
/*
* The generic shrinker function for all caches. Under linux a shrinker
* may not be tightly coupled with a slab cache. In fact linux always
* systematically trys calling all registered shrinker callbacks which
* report that they contain unused objects. Because of this we only
* register one shrinker function in the shim layer for all slab caches.
* We always attempt to shrink all caches when this generic shrinker
* is called. The shrinker should return the number of free objects
* in the cache when called with nr_to_scan == 0 but not attempt to
* free any objects. When nr_to_scan > 0 it is a request that nr_to_scan
* objects should be freed, because Solaris semantics are to free
* all available objects we may free more objects than requested.
*/
static int
spl_kmem_cache_generic_shrinker(int nr_to_scan, unsigned int gfp_mask)
{
spl_kmem_cache_t *skc;
int unused = 0;
down_read(&spl_kmem_cache_sem);
list_for_each_entry(skc, &spl_kmem_cache_list, skc_list) {
if (nr_to_scan)
spl_kmem_cache_reap_now(skc);
/*
* Presume everything alloc'ed in reclaimable, this ensures
* we are called again with nr_to_scan > 0 so can try and
* reclaim. The exact number is not important either so
* we forgo taking this already highly contented lock.
*/
unused += skc->skc_obj_alloc;
}
up_read(&spl_kmem_cache_sem);
return (unused * sysctl_vfs_cache_pressure) / 100;
}
/*
* Call the registered reclaim function for a cache. Depending on how
* many and which objects are released it may simply repopulate the
* local magazine which will then need to age-out. Objects which cannot
* fit in the magazine we will be released back to their slabs which will
* also need to age out before being release. This is all just best
* effort and we do not want to thrash creating and destroying slabs.
*/
void
spl_kmem_cache_reap_now(spl_kmem_cache_t *skc)
{
ENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
/* Prevent concurrent cache reaping when contended */
if (test_and_set_bit(KMC_BIT_REAPING, &skc->skc_flags)) {
EXIT;
return;
}
atomic_inc(&skc->skc_ref);
if (skc->skc_reclaim)
skc->skc_reclaim(skc->skc_private);
spl_slab_reclaim(skc, 0);
clear_bit(KMC_BIT_REAPING, &skc->skc_flags);
atomic_dec(&skc->skc_ref);
EXIT;
}
EXPORT_SYMBOL(spl_kmem_cache_reap_now);
/*
* Reap all free slabs from all registered caches.
*/
void
spl_kmem_reap(void)
{
spl_kmem_cache_generic_shrinker(KMC_REAP_CHUNK, GFP_KERNEL);
}
EXPORT_SYMBOL(spl_kmem_reap);
#if defined(DEBUG_KMEM) && defined(DEBUG_KMEM_TRACKING)
static char *
spl_sprintf_addr(kmem_debug_t *kd, char *str, int len, int min)
{
int size = ((len - 1) < kd->kd_size) ? (len - 1) : kd->kd_size;
int i, flag = 1;
ASSERT(str != NULL && len >= 17);
memset(str, 0, len);
/* Check for a fully printable string, and while we are at
* it place the printable characters in the passed buffer. */
for (i = 0; i < size; i++) {
str[i] = ((char *)(kd->kd_addr))[i];
if (isprint(str[i])) {
continue;
} else {
/* Minimum number of printable characters found
* to make it worthwhile to print this as ascii. */
if (i > min)
break;
flag = 0;
break;
}
}
if (!flag) {
sprintf(str, "%02x%02x%02x%02x%02x%02x%02x%02x",
*((uint8_t *)kd->kd_addr),
*((uint8_t *)kd->kd_addr + 2),
*((uint8_t *)kd->kd_addr + 4),
*((uint8_t *)kd->kd_addr + 6),
*((uint8_t *)kd->kd_addr + 8),
*((uint8_t *)kd->kd_addr + 10),
*((uint8_t *)kd->kd_addr + 12),
*((uint8_t *)kd->kd_addr + 14));
}
return str;
}
static int
spl_kmem_init_tracking(struct list_head *list, spinlock_t *lock, int size)
{
int i;
ENTRY;
spin_lock_init(lock);
INIT_LIST_HEAD(list);
for (i = 0; i < size; i++)
INIT_HLIST_HEAD(&kmem_table[i]);
RETURN(0);
}
static void
spl_kmem_fini_tracking(struct list_head *list, spinlock_t *lock)
{
unsigned long flags;
kmem_debug_t *kd;
char str[17];
ENTRY;
spin_lock_irqsave(lock, flags);
if (!list_empty(list))
printk(KERN_WARNING "%-16s %-5s %-16s %s:%s\n", "address",
"size", "data", "func", "line");
list_for_each_entry(kd, list, kd_list)
printk(KERN_WARNING "%p %-5d %-16s %s:%d\n", kd->kd_addr,
(int)kd->kd_size, spl_sprintf_addr(kd, str, 17, 8),
kd->kd_func, kd->kd_line);
spin_unlock_irqrestore(lock, flags);
EXIT;
}
#else /* DEBUG_KMEM && DEBUG_KMEM_TRACKING */
#define spl_kmem_init_tracking(list, lock, size)
#define spl_kmem_fini_tracking(list, lock)
#endif /* DEBUG_KMEM && DEBUG_KMEM_TRACKING */
int
spl_kmem_init(void)
{
int rc = 0;
ENTRY;
init_rwsem(&spl_kmem_cache_sem);
INIT_LIST_HEAD(&spl_kmem_cache_list);
#ifdef HAVE_SET_SHRINKER
spl_kmem_cache_shrinker = set_shrinker(KMC_DEFAULT_SEEKS,
spl_kmem_cache_generic_shrinker);
if (spl_kmem_cache_shrinker == NULL)
RETURN(rc = -ENOMEM);
#else
register_shrinker(&spl_kmem_cache_shrinker);
#endif
#ifdef DEBUG_KMEM
atomic64_set(&kmem_alloc_used, 0);
atomic64_set(&vmem_alloc_used, 0);
spl_kmem_init_tracking(&kmem_list, &kmem_lock, KMEM_TABLE_SIZE);
spl_kmem_init_tracking(&vmem_list, &vmem_lock, VMEM_TABLE_SIZE);
#endif
RETURN(rc);
}
void
spl_kmem_fini(void)
{
#ifdef DEBUG_KMEM
/* Display all unreclaimed memory addresses, including the
* allocation size and the first few bytes of what's located
* at that address to aid in debugging. Performance is not
* a serious concern here since it is module unload time. */
if (atomic64_read(&kmem_alloc_used) != 0)
CWARN("kmem leaked %ld/%ld bytes\n",
atomic64_read(&kmem_alloc_used), kmem_alloc_max);
if (atomic64_read(&vmem_alloc_used) != 0)
CWARN("vmem leaked %ld/%ld bytes\n",
atomic64_read(&vmem_alloc_used), vmem_alloc_max);
spl_kmem_fini_tracking(&kmem_list, &kmem_lock);
spl_kmem_fini_tracking(&vmem_list, &vmem_lock);
#endif /* DEBUG_KMEM */
ENTRY;
#ifdef HAVE_SET_SHRINKER
remove_shrinker(spl_kmem_cache_shrinker);
#else
unregister_shrinker(&spl_kmem_cache_shrinker);
#endif
EXIT;
}
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