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a073aeb060
freebsd-nq/module/spl/spl-kmem.c
Brian Behlendorf a073aeb060 Add KMC_SLAB cache type 
For small objects the Linux slab allocator has several advantages
over its counterpart in the SPL.  These include:

1) It is more memory-efficient and packs objects more tightly.
2) It is continually tuned to maximize performance.

Therefore it makes sense to layer the SPLs slab allocator on top
of the Linux slab allocator.  This allows us to leverage the
advantages above while preserving the Illumos semantics we depend
on.  However, there are some things we need to be careful of:

1) The Linux slab allocator was never designed to work well with
   large objects.  Because the SPL slab must still handle this use
   case a cut off limit was added to transition from Linux slab
   backed objects to kmem or vmem backed slabs.

   spl_kmem_cache_slab_limit - Objects less than or equal to this
   size in bytes will be backed by the Linux slab.  By default
   this value is zero which disables the Linux slab functionality.
   Reasonable values for this cut off limit are in the range of
   4096-16386 bytes.

   spl_kmem_cache_kmem_limit - Objects less than or equal to this
   size in bytes will be backed by a kmem slab.  Objects over this
   size will be vmem backed instead.  This value defaults to
   1/8 a page, or 512 bytes on an x86_64 architecture.

2) Be aware that using the Linux slab may inadvertently introduce
   new deadlocks.  Care has been taken previously to ensure that
   all allocations which occur in the write path use GFP_NOIO.
   However, there may be internal allocations performed in the
   Linux slab which do not honor these flags.  If this is the case
   a deadlock may occur.

The path forward is definitely to start relying on the Linux slab.
But for that to happen we need to start building confidence that
there aren't any unexpected surprises lurking for us.  And ideally
need to move completely away from using the SPLs slab for large
memory allocations.  This patch is a first step.

NOTES:
1) The KMC_NOMAGAZINE flag was leveraged to support the Linux slab
   backed caches but it is not supported for kmem/vmem backed caches.

2) Regardless of the spl_kmem_cache_*_limit settings a cache may
   be explicitly set to a given type by passed the KMC_KMEM,
   KMC_VMEM, or KMC_SLAB flags during cache creation.

3) The constructors, destructors, and reclaim callbacks are all
   functional and will be called regardless of the cache type.

4) KMC_SLAB caches will not appear in /proc/spl/kmem/slab due to
   the issues involved in presenting correct object accounting.
   Instead they will appear in /proc/slabinfo under the same names.

5) Several kmem SPLAT tests needed to be fixed because they relied
   incorrectly on internal kmem slab accounting.  With the updated
   test cases all the SPLAT tests pass as expected.

6) An autoconf test was added to ensure that the __GFP_COMP flag
   was correctly added to the default flags used when allocating
   a slab.  This is required to ensure all pages in higher order
   slabs are properly refcounted, see ae16ed9.

7) When using the SLUB allocator there is no need to attempt to
   set the __GFP_COMP flag.  This has been the default behavior
   for the SLUB since Linux 2.6.25.

8) When using the SLUB it may be desirable to set the slub_nomerge
   kernel parameter to prevent caches from being merged.

Original-patch-by: DHE <git@dehacked.net>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: DHE <git@dehacked.net>
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Closes #356
2014-05-22 10:28:01 -07:00

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/*****************************************************************************\
* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
* Copyright (C) 2007 The Regents of the University of California.
* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
* UCRL-CODE-235197
*
* This file is part of the SPL, Solaris Porting Layer.
* For details, see <http://zfsonlinux.org/>.
*
* The SPL 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.
*
* The SPL 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 the SPL. If not, see <http://www.gnu.org/licenses/>.
*****************************************************************************
* Solaris Porting Layer (SPL) Kmem Implementation.
\*****************************************************************************/
#include <sys/kmem.h>
#include <spl-debug.h>
#ifdef SS_DEBUG_SUBSYS
#undef SS_DEBUG_SUBSYS
#endif
#define SS_DEBUG_SUBSYS SS_KMEM
/*
* Within the scope of spl-kmem.c file the kmem_cache_* definitions
* are removed to allow access to the real Linux slab allocator.
*/
#undef kmem_cache_destroy
#undef kmem_cache_create
#undef kmem_cache_alloc
#undef kmem_cache_free
/*
* Cache expiration was implemented because it was part of the default Solaris
* kmem_cache behavior. The idea is that per-cpu objects which haven't been
* accessed in several seconds should be returned to the cache. On the other
* hand Linux slabs never move objects back to the slabs unless there is
* memory pressure on the system. By default the Linux method is enabled
* because it has been shown to improve responsiveness on low memory systems.
* This policy may be changed by setting KMC_EXPIRE_AGE or KMC_EXPIRE_MEM.
*/
unsigned int spl_kmem_cache_expire = KMC_EXPIRE_MEM;
EXPORT_SYMBOL(spl_kmem_cache_expire);
module_param(spl_kmem_cache_expire, uint, 0644);
MODULE_PARM_DESC(spl_kmem_cache_expire, "By age (0x1) or low memory (0x2)");
unsigned int spl_kmem_cache_obj_per_slab = SPL_KMEM_CACHE_OBJ_PER_SLAB;
module_param(spl_kmem_cache_obj_per_slab, uint, 0644);
MODULE_PARM_DESC(spl_kmem_cache_obj_per_slab, "Number of objects per slab");
unsigned int spl_kmem_cache_obj_per_slab_min = SPL_KMEM_CACHE_OBJ_PER_SLAB_MIN;
module_param(spl_kmem_cache_obj_per_slab_min, uint, 0644);
MODULE_PARM_DESC(spl_kmem_cache_obj_per_slab_min,
"Minimal number of objects per slab");
unsigned int spl_kmem_cache_max_size = 32;
module_param(spl_kmem_cache_max_size, uint, 0644);
MODULE_PARM_DESC(spl_kmem_cache_max_size, "Maximum size of slab in MB");
unsigned int spl_kmem_cache_slab_limit = 0;
module_param(spl_kmem_cache_slab_limit, uint, 0644);
MODULE_PARM_DESC(spl_kmem_cache_slab_limit,
"Objects less than N bytes use the Linux slab");
unsigned int spl_kmem_cache_kmem_limit = (PAGE_SIZE / 4);
module_param(spl_kmem_cache_kmem_limit, uint, 0644);
MODULE_PARM_DESC(spl_kmem_cache_kmem_limit,
"Objects less than N bytes use the kmalloc");
/*
* The minimum amount of memory measured in pages to be free at all
* times on the system. This is similar to Linux's zone->pages_min
* multiplied by the number of zones and is sized based on that.
*/
pgcnt_t minfree = 0;
EXPORT_SYMBOL(minfree);
/*
* The desired amount of memory measured in pages to be free at all
* times on the system. This is similar to Linux's zone->pages_low
* multiplied by the number of zones and is sized based on that.
* Assuming all zones are being used roughly equally, when we drop
* below this threshold asynchronous page reclamation is triggered.
*/
pgcnt_t desfree = 0;
EXPORT_SYMBOL(desfree);
/*
* When above this amount of memory measures in pages the system is
* determined to have enough free memory. This is similar to Linux's
* zone->pages_high multiplied by the number of zones and is sized based
* on that. Assuming all zones are being used roughly equally, when
* asynchronous page reclamation reaches this threshold it stops.
*/
pgcnt_t lotsfree = 0;
EXPORT_SYMBOL(lotsfree);
/* Unused always 0 in this implementation */
pgcnt_t needfree = 0;
EXPORT_SYMBOL(needfree);
pgcnt_t swapfs_minfree = 0;
EXPORT_SYMBOL(swapfs_minfree);
pgcnt_t swapfs_reserve = 0;
EXPORT_SYMBOL(swapfs_reserve);
vmem_t *heap_arena = NULL;
EXPORT_SYMBOL(heap_arena);
vmem_t *zio_alloc_arena = NULL;
EXPORT_SYMBOL(zio_alloc_arena);
vmem_t *zio_arena = NULL;
EXPORT_SYMBOL(zio_arena);
#ifndef HAVE_GET_VMALLOC_INFO
get_vmalloc_info_t get_vmalloc_info_fn = SYMBOL_POISON;
EXPORT_SYMBOL(get_vmalloc_info_fn);
#endif /* HAVE_GET_VMALLOC_INFO */
#ifdef HAVE_PGDAT_HELPERS
# ifndef HAVE_FIRST_ONLINE_PGDAT
first_online_pgdat_t first_online_pgdat_fn = SYMBOL_POISON;
EXPORT_SYMBOL(first_online_pgdat_fn);
# endif /* HAVE_FIRST_ONLINE_PGDAT */
# ifndef HAVE_NEXT_ONLINE_PGDAT
next_online_pgdat_t next_online_pgdat_fn = SYMBOL_POISON;
EXPORT_SYMBOL(next_online_pgdat_fn);
# endif /* HAVE_NEXT_ONLINE_PGDAT */
# ifndef HAVE_NEXT_ZONE
next_zone_t next_zone_fn = SYMBOL_POISON;
EXPORT_SYMBOL(next_zone_fn);
# endif /* HAVE_NEXT_ZONE */
#else /* HAVE_PGDAT_HELPERS */
# ifndef HAVE_PGDAT_LIST
struct pglist_data *pgdat_list_addr = SYMBOL_POISON;
EXPORT_SYMBOL(pgdat_list_addr);
# endif /* HAVE_PGDAT_LIST */
#endif /* HAVE_PGDAT_HELPERS */
#ifdef NEED_GET_ZONE_COUNTS
# ifndef HAVE_GET_ZONE_COUNTS
get_zone_counts_t get_zone_counts_fn = SYMBOL_POISON;
EXPORT_SYMBOL(get_zone_counts_fn);
# endif /* HAVE_GET_ZONE_COUNTS */
unsigned long
spl_global_page_state(spl_zone_stat_item_t item)
{
unsigned long active;
unsigned long inactive;
unsigned long free;
get_zone_counts(&active, &inactive, &free);
switch (item) {
case SPL_NR_FREE_PAGES: return free;
case SPL_NR_INACTIVE: return inactive;
case SPL_NR_ACTIVE: return active;
default: ASSERT(0); /* Unsupported */
}
return 0;
}
#else
# ifdef HAVE_GLOBAL_PAGE_STATE
unsigned long
spl_global_page_state(spl_zone_stat_item_t item)
{
unsigned long pages = 0;
switch (item) {
case SPL_NR_FREE_PAGES:
# ifdef HAVE_ZONE_STAT_ITEM_NR_FREE_PAGES
pages += global_page_state(NR_FREE_PAGES);
# endif
break;
case SPL_NR_INACTIVE:
# ifdef HAVE_ZONE_STAT_ITEM_NR_INACTIVE
pages += global_page_state(NR_INACTIVE);
# endif
# ifdef HAVE_ZONE_STAT_ITEM_NR_INACTIVE_ANON
pages += global_page_state(NR_INACTIVE_ANON);
# endif
# ifdef HAVE_ZONE_STAT_ITEM_NR_INACTIVE_FILE
pages += global_page_state(NR_INACTIVE_FILE);
# endif
break;
case SPL_NR_ACTIVE:
# ifdef HAVE_ZONE_STAT_ITEM_NR_ACTIVE
pages += global_page_state(NR_ACTIVE);
# endif
# ifdef HAVE_ZONE_STAT_ITEM_NR_ACTIVE_ANON
pages += global_page_state(NR_ACTIVE_ANON);
# endif
# ifdef HAVE_ZONE_STAT_ITEM_NR_ACTIVE_FILE
pages += global_page_state(NR_ACTIVE_FILE);
# endif
break;
default:
ASSERT(0); /* Unsupported */
}
return pages;
}
# else
# error "Both global_page_state() and get_zone_counts() unavailable"
# endif /* HAVE_GLOBAL_PAGE_STATE */
#endif /* NEED_GET_ZONE_COUNTS */
EXPORT_SYMBOL(spl_global_page_state);
#ifndef HAVE_SHRINK_DCACHE_MEMORY
shrink_dcache_memory_t shrink_dcache_memory_fn = SYMBOL_POISON;
EXPORT_SYMBOL(shrink_dcache_memory_fn);
#endif /* HAVE_SHRINK_DCACHE_MEMORY */
#ifndef HAVE_SHRINK_ICACHE_MEMORY
shrink_icache_memory_t shrink_icache_memory_fn = SYMBOL_POISON;
EXPORT_SYMBOL(shrink_icache_memory_fn);
#endif /* HAVE_SHRINK_ICACHE_MEMORY */
pgcnt_t
spl_kmem_availrmem(void)
{
/* The amount of easily available memory */
return (spl_global_page_state(SPL_NR_FREE_PAGES) +
spl_global_page_state(SPL_NR_INACTIVE));
}
EXPORT_SYMBOL(spl_kmem_availrmem);
size_t
vmem_size(vmem_t *vmp, int typemask)
{
struct vmalloc_info vmi;
size_t size = 0;
ASSERT(vmp == NULL);
ASSERT(typemask & (VMEM_ALLOC | VMEM_FREE));
get_vmalloc_info(&vmi);
if (typemask & VMEM_ALLOC)
size += (size_t)vmi.used;
if (typemask & VMEM_FREE)
size += (size_t)(VMALLOC_TOTAL - vmi.used);
return size;
}
EXPORT_SYMBOL(vmem_size);
int
kmem_debugging(void)
{
return 0;
}
EXPORT_SYMBOL(kmem_debugging);
#ifndef HAVE_KVASPRINTF
/* Simplified asprintf. */
char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap)
{
unsigned int len;
char *p;
va_list aq;
va_copy(aq, ap);
len = vsnprintf(NULL, 0, fmt, aq);
va_end(aq);
p = kmalloc(len+1, gfp);
if (!p)
return NULL;
vsnprintf(p, len+1, fmt, ap);
return p;
}
EXPORT_SYMBOL(kvasprintf);
#endif /* HAVE_KVASPRINTF */
char *
kmem_vasprintf(const char *fmt, va_list ap)
{
va_list aq;
char *ptr;
do {
va_copy(aq, ap);
ptr = kvasprintf(GFP_KERNEL, fmt, aq);
va_end(aq);
} while (ptr == NULL);
return ptr;
}
EXPORT_SYMBOL(kmem_vasprintf);
char *
kmem_asprintf(const char *fmt, ...)
{
va_list ap;
char *ptr;
do {
va_start(ap, fmt);
ptr = kvasprintf(GFP_KERNEL, fmt, ap);
va_end(ap);
} while (ptr == NULL);
return ptr;
}
EXPORT_SYMBOL(kmem_asprintf);
static char *
__strdup(const char *str, int flags)
{
char *ptr;
int n;
n = strlen(str);
ptr = kmalloc_nofail(n + 1, flags);
if (ptr)
memcpy(ptr, str, n + 1);
return ptr;
}
char *
strdup(const char *str)
{
return __strdup(str, KM_SLEEP);
}
EXPORT_SYMBOL(strdup);
void
strfree(char *str)
{
kfree(str);
}
EXPORT_SYMBOL(strfree);
/*
* Memory allocation interfaces and debugging for basic kmem_*
* and vmem_* style memory allocation. When DEBUG_KMEM is enabled
* the SPL will keep track of the total memory allocated, and
* report any memory leaked when the module is unloaded.
*/
#ifdef DEBUG_KMEM
/* Shim layer memory accounting */
# ifdef HAVE_ATOMIC64_T
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;
# else /* HAVE_ATOMIC64_T */
atomic_t kmem_alloc_used = ATOMIC_INIT(0);
unsigned long long kmem_alloc_max = 0;
atomic_t vmem_alloc_used = ATOMIC_INIT(0);
unsigned long long vmem_alloc_max = 0;
# endif /* HAVE_ATOMIC64_T */
EXPORT_SYMBOL(kmem_alloc_used);
EXPORT_SYMBOL(kmem_alloc_max);
EXPORT_SYMBOL(vmem_alloc_used);
EXPORT_SYMBOL(vmem_alloc_max);
/* When DEBUG_KMEM_TRACKING is enabled not only will total bytes be tracked
* but also the location of every alloc and free. When the SPL module is
* unloaded a list of all leaked addresses and where they were allocated
* will be dumped to the console. Enabling this feature has a significant
* impact on performance but it makes finding memory leaks straight forward.
*
* Not 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.
*/
# ifdef DEBUG_KMEM_TRACKING
# 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);
static kmem_debug_t *
kmem_del_init(spinlock_t *lock, struct hlist_head *table, int bits, const void *addr)
{
struct hlist_head *head;
struct hlist_node *node;
struct kmem_debug *p;
unsigned long flags;
SENTRY;
spin_lock_irqsave(lock, flags);
head = &table[hash_ptr((void *)addr, bits)];
hlist_for_each(node, head) {
p = list_entry(node, struct kmem_debug, 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);
SRETURN(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;
SENTRY;
/* Function may be called with KM_NOSLEEP so failure is possible */
dptr = (kmem_debug_t *) kmalloc_nofail(sizeof(kmem_debug_t),
flags & ~__GFP_ZERO);
if (unlikely(dptr == NULL)) {
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING, "debug "
"kmem_alloc(%ld, 0x%x) at %s:%d failed (%lld/%llu)\n",
sizeof(kmem_debug_t), flags, func, line,
kmem_alloc_used_read(), kmem_alloc_max);
} 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) && !(flags & KM_NODEBUG))) {
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING, "large "
"kmem_alloc(%llu, 0x%x) at %s:%d (%lld/%llu)\n",
(unsigned long long) size, flags, func, line,
kmem_alloc_used_read(), kmem_alloc_max);
spl_debug_dumpstack(NULL);
}
/*
* We use __strdup() 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.
* This can only fail in the KM_NOSLEEP case.
*/
dptr->kd_func = __strdup(func, flags & ~__GFP_ZERO);
if (unlikely(dptr->kd_func == NULL)) {
kfree(dptr);
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING,
"debug __strdup() at %s:%d failed (%lld/%llu)\n",
func, line, kmem_alloc_used_read(), kmem_alloc_max);
goto out;
}
/* Use the correct allocator */
if (node_alloc) {
ASSERT(!(flags & __GFP_ZERO));
ptr = kmalloc_node_nofail(size, flags, node);
} else if (flags & __GFP_ZERO) {
ptr = kzalloc_nofail(size, flags & ~__GFP_ZERO);
} else {
ptr = kmalloc_nofail(size, flags);
}
if (unlikely(ptr == NULL)) {
kfree(dptr->kd_func);
kfree(dptr);
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING, "kmem_alloc"
"(%llu, 0x%x) at %s:%d failed (%lld/%llu)\n",
(unsigned long long) size, flags, func, line,
kmem_alloc_used_read(), kmem_alloc_max);
goto out;
}
kmem_alloc_used_add(size);
if (unlikely(kmem_alloc_used_read() > kmem_alloc_max))
kmem_alloc_max = kmem_alloc_used_read();
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(&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);
SDEBUG_LIMIT(SD_INFO,
"kmem_alloc(%llu, 0x%x) at %s:%d = %p (%lld/%llu)\n",
(unsigned long long) size, flags, func, line, ptr,
kmem_alloc_used_read(), kmem_alloc_max);
}
out:
SRETURN(ptr);
}
EXPORT_SYMBOL(kmem_alloc_track);
void
kmem_free_track(const void *ptr, size_t size)
{
kmem_debug_t *dptr;
SENTRY;
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);
/* Must exist in hash due to kmem_alloc() */
ASSERT(dptr);
/* 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);
kmem_alloc_used_sub(size);
SDEBUG_LIMIT(SD_INFO, "kmem_free(%p, %llu) (%lld/%llu)\n", ptr,
(unsigned long long) size, kmem_alloc_used_read(),
kmem_alloc_max);
kfree(dptr->kd_func);
memset((void *)dptr, 0x5a, sizeof(kmem_debug_t));
kfree(dptr);
memset((void *)ptr, 0x5a, size);
kfree(ptr);
SEXIT;
}
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;
SENTRY;
ASSERT(flags & KM_SLEEP);
/* Function may be called with KM_NOSLEEP so failure is possible */
dptr = (kmem_debug_t *) kmalloc_nofail(sizeof(kmem_debug_t),
flags & ~__GFP_ZERO);
if (unlikely(dptr == NULL)) {
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING, "debug "
"vmem_alloc(%ld, 0x%x) at %s:%d failed (%lld/%llu)\n",
sizeof(kmem_debug_t), flags, func, line,
vmem_alloc_used_read(), vmem_alloc_max);
} else {
/*
* We use __strdup() 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.
* This can never fail because we have already asserted
* that flags is KM_SLEEP.
*/
dptr->kd_func = __strdup(func, flags & ~__GFP_ZERO);
if (unlikely(dptr->kd_func == NULL)) {
kfree(dptr);
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING,
"debug __strdup() at %s:%d failed (%lld/%llu)\n",
func, line, vmem_alloc_used_read(), vmem_alloc_max);
goto out;
}
/* Use the correct allocator */
if (flags & __GFP_ZERO) {
ptr = vzalloc_nofail(size, flags & ~__GFP_ZERO);
} else {
ptr = vmalloc_nofail(size, flags);
}
if (unlikely(ptr == NULL)) {
kfree(dptr->kd_func);
kfree(dptr);
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING, "vmem_alloc"
"(%llu, 0x%x) at %s:%d failed (%lld/%llu)\n",
(unsigned long long) size, flags, func, line,
vmem_alloc_used_read(), vmem_alloc_max);
goto out;
}
vmem_alloc_used_add(size);
if (unlikely(vmem_alloc_used_read() > vmem_alloc_max))
vmem_alloc_max = vmem_alloc_used_read();
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(&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);
SDEBUG_LIMIT(SD_INFO,
"vmem_alloc(%llu, 0x%x) at %s:%d = %p (%lld/%llu)\n",
(unsigned long long) size, flags, func, line,
ptr, vmem_alloc_used_read(), vmem_alloc_max);
}
out:
SRETURN(ptr);
}
EXPORT_SYMBOL(vmem_alloc_track);
void
vmem_free_track(const void *ptr, size_t size)
{
kmem_debug_t *dptr;
SENTRY;
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);
/* Must exist in hash due to vmem_alloc() */
ASSERT(dptr);
/* 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);
vmem_alloc_used_sub(size);
SDEBUG_LIMIT(SD_INFO, "vmem_free(%p, %llu) (%lld/%llu)\n", ptr,
(unsigned long long) size, vmem_alloc_used_read(),
vmem_alloc_max);
kfree(dptr->kd_func);
memset((void *)dptr, 0x5a, sizeof(kmem_debug_t));
kfree(dptr);
memset((void *)ptr, 0x5a, size);
vfree(ptr);
SEXIT;
}
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;
SENTRY;
/*
* 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) && !(flags & KM_NODEBUG))) {
SDEBUG(SD_CONSOLE | SD_WARNING,
"large kmem_alloc(%llu, 0x%x) at %s:%d (%lld/%llu)\n",
(unsigned long long) size, flags, func, line,
kmem_alloc_used_read(), kmem_alloc_max);
dump_stack();
}
/* Use the correct allocator */
if (node_alloc) {
ASSERT(!(flags & __GFP_ZERO));
ptr = kmalloc_node_nofail(size, flags, node);
} else if (flags & __GFP_ZERO) {
ptr = kzalloc_nofail(size, flags & (~__GFP_ZERO));
} else {
ptr = kmalloc_nofail(size, flags);
}
if (unlikely(ptr == NULL)) {
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING,
"kmem_alloc(%llu, 0x%x) at %s:%d failed (%lld/%llu)\n",
(unsigned long long) size, flags, func, line,
kmem_alloc_used_read(), kmem_alloc_max);
} else {
kmem_alloc_used_add(size);
if (unlikely(kmem_alloc_used_read() > kmem_alloc_max))
kmem_alloc_max = kmem_alloc_used_read();
SDEBUG_LIMIT(SD_INFO,
"kmem_alloc(%llu, 0x%x) at %s:%d = %p (%lld/%llu)\n",
(unsigned long long) size, flags, func, line, ptr,
kmem_alloc_used_read(), kmem_alloc_max);
}
SRETURN(ptr);
}
EXPORT_SYMBOL(kmem_alloc_debug);
void
kmem_free_debug(const void *ptr, size_t size)
{
SENTRY;
ASSERTF(ptr || size > 0, "ptr: %p, size: %llu", ptr,
(unsigned long long) size);
kmem_alloc_used_sub(size);
SDEBUG_LIMIT(SD_INFO, "kmem_free(%p, %llu) (%lld/%llu)\n", ptr,
(unsigned long long) size, kmem_alloc_used_read(),
kmem_alloc_max);
kfree(ptr);
SEXIT;
}
EXPORT_SYMBOL(kmem_free_debug);
void *
vmem_alloc_debug(size_t size, int flags, const char *func, int line)
{
void *ptr;
SENTRY;
ASSERT(flags & KM_SLEEP);
/* Use the correct allocator */
if (flags & __GFP_ZERO) {
ptr = vzalloc_nofail(size, flags & (~__GFP_ZERO));
} else {
ptr = vmalloc_nofail(size, flags);
}
if (unlikely(ptr == NULL)) {
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING,
"vmem_alloc(%llu, 0x%x) at %s:%d failed (%lld/%llu)\n",
(unsigned long long) size, flags, func, line,
vmem_alloc_used_read(), vmem_alloc_max);
} else {
vmem_alloc_used_add(size);
if (unlikely(vmem_alloc_used_read() > vmem_alloc_max))
vmem_alloc_max = vmem_alloc_used_read();
SDEBUG_LIMIT(SD_INFO, "vmem_alloc(%llu, 0x%x) = %p "
"(%lld/%llu)\n", (unsigned long long) size, flags, ptr,
vmem_alloc_used_read(), vmem_alloc_max);
}
SRETURN(ptr);
}
EXPORT_SYMBOL(vmem_alloc_debug);
void
vmem_free_debug(const void *ptr, size_t size)
{
SENTRY;
ASSERTF(ptr || size > 0, "ptr: %p, size: %llu", ptr,
(unsigned long long) size);
vmem_alloc_used_sub(size);
SDEBUG_LIMIT(SD_INFO, "vmem_free(%p, %llu) (%lld/%llu)\n", ptr,
(unsigned long long) size, vmem_alloc_used_read(),
vmem_alloc_max);
vfree(ptr);
SEXIT;
}
EXPORT_SYMBOL(vmem_free_debug);
# endif /* DEBUG_KMEM_TRACKING */
#endif /* DEBUG_KMEM */
/*
* Slab allocation interfaces
*
* While the Linux slab implementation was inspired by the Solaris
* implementation 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 contiguous 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 guarantees 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 advantageous 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 */
taskq_t *spl_kmem_cache_taskq; /* Task queue for ageing / reclaim */
static void spl_cache_shrink(spl_kmem_cache_t *skc, void *obj);
SPL_SHRINKER_CALLBACK_FWD_DECLARE(spl_kmem_cache_generic_shrinker);
SPL_SHRINKER_DECLARE(spl_kmem_cache_shrinker,
spl_kmem_cache_generic_shrinker, KMC_DEFAULT_SEEKS);
static void *
kv_alloc(spl_kmem_cache_t *skc, int size, int flags)
{
void *ptr;
ASSERT(ISP2(size));
if (skc->skc_flags & KMC_KMEM)
ptr = (void *)__get_free_pages(flags | __GFP_COMP,
get_order(size));
else
ptr = __vmalloc(size, flags | __GFP_HIGHMEM, PAGE_KERNEL);
/* Resulting allocated memory will be page aligned */
ASSERT(IS_P2ALIGNED(ptr, PAGE_SIZE));
return ptr;
}
static void
kv_free(spl_kmem_cache_t *skc, void *ptr, int size)
{
ASSERT(IS_P2ALIGNED(ptr, PAGE_SIZE));
ASSERT(ISP2(size));
/*
* The Linux direct reclaim path uses this out of band value to
* determine if forward progress is being made. Normally this is
* incremented by kmem_freepages() which is part of the various
* Linux slab implementations. However, since we are using none
* of that infrastructure we are responsible for incrementing it.
*/
if (current->reclaim_state)
current->reclaim_state->reclaimed_slab += size >> PAGE_SHIFT;
if (skc->skc_flags & KMC_KMEM)
free_pages((unsigned long)ptr, get_order(size));
else
vfree(ptr);
}
/*
* Required space for each aligned sks.
*/
static inline uint32_t
spl_sks_size(spl_kmem_cache_t *skc)
{
return P2ROUNDUP_TYPED(sizeof(spl_kmem_slab_t),
skc->skc_obj_align, uint32_t);
}
/*
* Required space for each aligned object.
*/
static inline uint32_t
spl_obj_size(spl_kmem_cache_t *skc)
{
uint32_t align = skc->skc_obj_align;
return P2ROUNDUP_TYPED(skc->skc_obj_size, align, uint32_t) +
P2ROUNDUP_TYPED(sizeof(spl_kmem_obj_t), align, uint32_t);
}
/*
* Lookup the spl_kmem_object_t for an object given that object.
*/
static inline spl_kmem_obj_t *
spl_sko_from_obj(spl_kmem_cache_t *skc, void *obj)
{
return obj + P2ROUNDUP_TYPED(skc->skc_obj_size,
skc->skc_obj_align, uint32_t);
}
/*
* Required space for each offslab object taking in to account alignment
* restrictions and the power-of-two requirement of kv_alloc().
*/
static inline uint32_t
spl_offslab_size(spl_kmem_cache_t *skc)
{
return 1UL << (highbit(spl_obj_size(skc)) + 1);
}
/*
* 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 contiguous pages.
* For this reason we shift to vmem_alloc() for slabs of large objects
* which removes the need for contiguous 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 acquiring 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;
uint32_t obj_size, offslab_size = 0;
int i, rc = 0;
base = kv_alloc(skc, skc->skc_slab_size, flags);
if (base == NULL)
SRETURN(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;
obj_size = spl_obj_size(skc);
if (skc->skc_flags & KMC_OFFSLAB)
offslab_size = spl_offslab_size(skc);
for (i = 0; i < sks->sks_objs; i++) {
if (skc->skc_flags & KMC_OFFSLAB) {
obj = kv_alloc(skc, offslab_size, flags);
if (!obj)
SGOTO(out, rc = -ENOMEM);
} else {
obj = base + spl_sks_size(skc) + (i * obj_size);
}
ASSERT(IS_P2ALIGNED(obj, skc->skc_obj_align));
sko = spl_sko_from_obj(skc, obj);
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, offslab_size);
kv_free(skc, base, skc->skc_slab_size);
sks = NULL;
}
SRETURN(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;
SENTRY;
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));
/*
* Update slab/objects counters in the cache, then remove the
* slab from the skc->skc_partial_list. Finally add the slab
* and all its objects in to the private work lists where the
* destructors will be called and the memory freed to the system.
*/
skc->skc_obj_total -= sks->sks_objs;
skc->skc_slab_total--;
list_del(&sks->sks_list);
list_add(&sks->sks_list, sks_list);
list_splice_init(&sks->sks_free_list, sko_list);
SEXIT;
}
/*
* 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 to avoid thrashing. The count argument is
* passed to optionally cap the number of slabs reclaimed, a count
* of zero means try and reclaim everything. When flag is set we
* always free an available slab regardless of age.
*/
static void
spl_slab_reclaim(spl_kmem_cache_t *skc, int count, int flag)
{
spl_kmem_slab_t *sks, *m;
spl_kmem_obj_t *sko, *n;
LIST_HEAD(sks_list);
LIST_HEAD(sko_list);
uint32_t size = 0;
int i = 0;
SENTRY;
/*
* 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.
*/
spin_lock(&skc->skc_lock);
list_for_each_entry_safe_reverse(sks,m,&skc->skc_partial_list,sks_list){
/*
* All empty slabs are at the end of skc->skc_partial_list,
* therefore once a non-empty slab is found we can stop
* scanning. Additionally, stop when reaching the target
* reclaim 'count' if a non-zero threshold is given.
*/
if ((sks->sks_ref > 0) || (count && i >= count))
break;
if (time_after(jiffies,sks->sks_age+skc->skc_delay*HZ)||flag) {
spl_slab_free(sks, &sks_list, &sko_list);
i++;
}
}
spin_unlock(&skc->skc_lock);
/*
* The following two loops ensure all the object destructors are
* run, any offslab objects are freed, and the slabs themselves
* are freed. This is all done outside the skc->skc_lock since
* this allows the destructor to sleep, and allows us to perform
* a conditional reschedule when a freeing a large number of
* objects and slabs back to the system.
*/
if (skc->skc_flags & KMC_OFFSLAB)
size = spl_offslab_size(skc);
list_for_each_entry_safe(sko, n, &sko_list, sko_list) {
ASSERT(sko->sko_magic == SKO_MAGIC);
if (skc->skc_dtor)
skc->skc_dtor(sko->sko_addr, skc->skc_private);
if (skc->skc_flags & KMC_OFFSLAB)
kv_free(skc, sko->sko_addr, size);
}
list_for_each_entry_safe(sks, m, &sks_list, sks_list) {
ASSERT(sks->sks_magic == SKS_MAGIC);
kv_free(skc, sks, skc->skc_slab_size);
}
SEXIT;
}
static spl_kmem_emergency_t *
spl_emergency_search(struct rb_root *root, void *obj)
{
struct rb_node *node = root->rb_node;
spl_kmem_emergency_t *ske;
unsigned long address = (unsigned long)obj;
while (node) {
ske = container_of(node, spl_kmem_emergency_t, ske_node);
if (address < (unsigned long)ske->ske_obj)
node = node->rb_left;
else if (address > (unsigned long)ske->ske_obj)
node = node->rb_right;
else
return ske;
}
return NULL;
}
static int
spl_emergency_insert(struct rb_root *root, spl_kmem_emergency_t *ske)
{
struct rb_node **new = &(root->rb_node), *parent = NULL;
spl_kmem_emergency_t *ske_tmp;
unsigned long address = (unsigned long)ske->ske_obj;
while (*new) {
ske_tmp = container_of(*new, spl_kmem_emergency_t, ske_node);
parent = *new;
if (address < (unsigned long)ske_tmp->ske_obj)
new = &((*new)->rb_left);
else if (address > (unsigned long)ske_tmp->ske_obj)
new = &((*new)->rb_right);
else
return 0;
}
rb_link_node(&ske->ske_node, parent, new);
rb_insert_color(&ske->ske_node, root);
return 1;
}
/*
* Allocate a single emergency object and track it in a red black tree.
*/
static int
spl_emergency_alloc(spl_kmem_cache_t *skc, int flags, void **obj)
{
spl_kmem_emergency_t *ske;
int empty;
SENTRY;
/* Last chance use a partial slab if one now exists */
spin_lock(&skc->skc_lock);
empty = list_empty(&skc->skc_partial_list);
spin_unlock(&skc->skc_lock);
if (!empty)
SRETURN(-EEXIST);
ske = kmalloc(sizeof(*ske), flags);
if (ske == NULL)
SRETURN(-ENOMEM);
ske->ske_obj = kmalloc(skc->skc_obj_size, flags);
if (ske->ske_obj == NULL) {
kfree(ske);
SRETURN(-ENOMEM);
}
spin_lock(&skc->skc_lock);
empty = spl_emergency_insert(&skc->skc_emergency_tree, ske);
if (likely(empty)) {
skc->skc_obj_total++;
skc->skc_obj_emergency++;
if (skc->skc_obj_emergency > skc->skc_obj_emergency_max)
skc->skc_obj_emergency_max = skc->skc_obj_emergency;
}
spin_unlock(&skc->skc_lock);
if (unlikely(!empty)) {
kfree(ske->ske_obj);
kfree(ske);
SRETURN(-EINVAL);
}
if (skc->skc_ctor)
skc->skc_ctor(ske->ske_obj, skc->skc_private, flags);
*obj = ske->ske_obj;
SRETURN(0);
}
/*
* Locate the passed object in the red black tree and free it.
*/
static int
spl_emergency_free(spl_kmem_cache_t *skc, void *obj)
{
spl_kmem_emergency_t *ske;
SENTRY;
spin_lock(&skc->skc_lock);
ske = spl_emergency_search(&skc->skc_emergency_tree, obj);
if (likely(ske)) {
rb_erase(&ske->ske_node, &skc->skc_emergency_tree);
skc->skc_obj_emergency--;
skc->skc_obj_total--;
}
spin_unlock(&skc->skc_lock);
if (unlikely(ske == NULL))
SRETURN(-ENOENT);
if (skc->skc_dtor)
skc->skc_dtor(ske->ske_obj, skc->skc_private);
kfree(ske->ske_obj);
kfree(ske);
SRETURN(0);
}
/*
* Release objects from the per-cpu magazine back to their slab. The flush
* argument contains the max number of entries to remove from the magazine.
*/
static void
__spl_cache_flush(spl_kmem_cache_t *skc, spl_kmem_magazine_t *skm, int flush)
{
int i, count = MIN(flush, skm->skm_avail);
SENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(skm->skm_magic == SKM_MAGIC);
ASSERT(spin_is_locked(&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);
SEXIT;
}
static void
spl_cache_flush(spl_kmem_cache_t *skc, spl_kmem_magazine_t *skm, int flush)
{
spin_lock(&skc->skc_lock);
__spl_cache_flush(skc, skm, flush);
spin_unlock(&skc->skc_lock);
}
static void
spl_magazine_age(void *data)
{
spl_kmem_cache_t *skc = (spl_kmem_cache_t *)data;
spl_kmem_magazine_t *skm = skc->skc_mag[smp_processor_id()];
ASSERT(skm->skm_magic == SKM_MAGIC);
ASSERT(skm->skm_cpu == smp_processor_id());
ASSERT(irqs_disabled());
/* There are no available objects or they are too young to age out */
if ((skm->skm_avail == 0) ||
time_before(jiffies, skm->skm_age + skc->skc_delay * HZ))
return;
/*
* Because we're executing in interrupt context we may have
* interrupted the holder of this lock. To avoid a potential
* deadlock return if the lock is contended.
*/
if (!spin_trylock(&skc->skc_lock))
return;
__spl_cache_flush(skc, skm, skm->skm_refill);
spin_unlock(&skc->skc_lock);
}
/*
* Called regularly to keep a downward pressure on the cache.
*
* Objects older than skc->skc_delay seconds in the per-cpu magazines will
* be returned to the caches. This is done to prevent idle magazines from
* holding memory which could be better used elsewhere. The delay is
* present to prevent thrashing the magazine.
*
* The newly released objects may result in empty partial slabs. Those
* slabs should be released to the system. Otherwise moving the objects
* out of the magazines is just wasted work.
*/
static void
spl_cache_age(void *data)
{
spl_kmem_cache_t *skc = (spl_kmem_cache_t *)data;
taskqid_t id = 0;
ASSERT(skc->skc_magic == SKC_MAGIC);
/* Dynamically disabled at run time */
if (!(spl_kmem_cache_expire & KMC_EXPIRE_AGE))
return;
atomic_inc(&skc->skc_ref);
if (!(skc->skc_flags & KMC_NOMAGAZINE))
spl_on_each_cpu(spl_magazine_age, skc, 1);
spl_slab_reclaim(skc, skc->skc_reap, 0);
while (!test_bit(KMC_BIT_DESTROY, &skc->skc_flags) && !id) {
id = taskq_dispatch_delay(
spl_kmem_cache_taskq, spl_cache_age, skc, TQ_SLEEP,
ddi_get_lbolt() + skc->skc_delay / 3 * HZ);
/* Destroy issued after dispatch immediately cancel it */
if (test_bit(KMC_BIT_DESTROY, &skc->skc_flags) && id)
taskq_cancel_id(spl_kmem_cache_taskq, id);
}
spin_lock(&skc->skc_lock);
skc->skc_taskqid = id;
spin_unlock(&skc->skc_lock);
atomic_dec(&skc->skc_ref);
}
/*
* Size a slab based on the size of each aligned 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)
{
uint32_t sks_size, obj_size, max_size;
if (skc->skc_flags & KMC_OFFSLAB) {
*objs = spl_kmem_cache_obj_per_slab;
*size = P2ROUNDUP(sizeof(spl_kmem_slab_t), PAGE_SIZE);
SRETURN(0);
} else {
sks_size = spl_sks_size(skc);
obj_size = spl_obj_size(skc);
if (skc->skc_flags & KMC_KMEM)
max_size = ((uint32_t)1 << (MAX_ORDER-3)) * PAGE_SIZE;
else
max_size = (spl_kmem_cache_max_size * 1024 * 1024);
/* Power of two sized slab */
for (*size = PAGE_SIZE; *size <= max_size; *size *= 2) {
*objs = (*size - sks_size) / obj_size;
if (*objs >= spl_kmem_cache_obj_per_slab)
SRETURN(0);
}
/*
* Unable to satisfy target objects per slab, fall back 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))
SRETURN(0);
}
SRETURN(-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)
{
uint32_t obj_size = spl_obj_size(skc);
int size;
SENTRY;
/* Per-magazine sizes below assume a 4Kib page size */
if (obj_size > (PAGE_SIZE * 256))
size = 4; /* Minimum 4Mib per-magazine */
else if (obj_size > (PAGE_SIZE * 32))
size = 16; /* Minimum 2Mib per-magazine */
else if (obj_size > (PAGE_SIZE))
size = 64; /* Minimum 256Kib per-magazine */
else if (obj_size > (PAGE_SIZE / 4))
size = 128; /* Minimum 128Kib per-magazine */
else
size = 256;
SRETURN(size);
}
/*
* Allocate a per-cpu magazine to associate with a specific core.
*/
static spl_kmem_magazine_t *
spl_magazine_alloc(spl_kmem_cache_t *skc, int cpu)
{
spl_kmem_magazine_t *skm;
int size = sizeof(spl_kmem_magazine_t) +
sizeof(void *) * skc->skc_mag_size;
SENTRY;
skm = kmem_alloc_node(size, KM_SLEEP, cpu_to_node(cpu));
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_cache = skc;
skm->skm_age = jiffies;
skm->skm_cpu = cpu;
}
SRETURN(skm);
}
/*
* Free a per-cpu magazine associated 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;
SENTRY;
ASSERT(skm->skm_magic == SKM_MAGIC);
ASSERT(skm->skm_avail == 0);
kmem_free(skm, size);
SEXIT;
}
/*
* Create all pre-cpu magazines of reasonable sizes.
*/
static int
spl_magazine_create(spl_kmem_cache_t *skc)
{
int i;
SENTRY;
if (skc->skc_flags & KMC_NOMAGAZINE)
SRETURN(0);
skc->skc_mag_size = spl_magazine_size(skc);
skc->skc_mag_refill = (skc->skc_mag_size + 1) / 2;
for_each_online_cpu(i) {
skc->skc_mag[i] = spl_magazine_alloc(skc, i);
if (!skc->skc_mag[i]) {
for (i--; i >= 0; i--)
spl_magazine_free(skc->skc_mag[i]);
SRETURN(-ENOMEM);
}
}
SRETURN(0);
}
/*
* Destroy all pre-cpu magazines.
*/
static void
spl_magazine_destroy(spl_kmem_cache_t *skc)
{
spl_kmem_magazine_t *skm;
int i;
SENTRY;
if (skc->skc_flags & KMC_NOMAGAZINE) {
SEXIT;
return;
}
for_each_online_cpu(i) {
skm = skc->skc_mag[i];
spl_cache_flush(skc, skm, skm->skm_avail);
spl_magazine_free(skm);
}
SEXIT;
}
/*
* 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_NOHASH Disable hashing (unsupported)
* KMC_QCACHE Disable qcache (unsupported)
* KMC_NOMAGAZINE Enabled for kmem/vmem, Disabled for Linux slab
* KMC_KMEM Force kmem backed cache
* KMC_VMEM Force vmem backed cache
* KMC_SLAB Force Linux slab 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;
SENTRY;
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);
might_sleep();
/*
* Allocate memory for a new cache an initialize it. Unfortunately,
* this usually ends up being a large allocation of ~32k because
* we need to allocate enough memory for the worst case number of
* cpus in the magazine, skc_mag[NR_CPUS]. Because of this we
* explicitly pass KM_NODEBUG to suppress the kmem warning
*/
skc = kmem_zalloc(sizeof(*skc), KM_SLEEP| KM_NODEBUG);
if (skc == NULL)
SRETURN(NULL);
skc->skc_magic = SKC_MAGIC;
skc->skc_name_size = strlen(name) + 1;
skc->skc_name = (char *)kmem_alloc(skc->skc_name_size, KM_SLEEP);
if (skc->skc_name == NULL) {
kmem_free(skc, sizeof(*skc));
SRETURN(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_linux_cache = NULL;
skc->skc_flags = flags;
skc->skc_obj_size = size;
skc->skc_obj_align = SPL_KMEM_CACHE_ALIGN;
skc->skc_delay = SPL_KMEM_CACHE_DELAY;
skc->skc_reap = SPL_KMEM_CACHE_REAP;
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);
skc->skc_emergency_tree = RB_ROOT;
spin_lock_init(&skc->skc_lock);
init_waitqueue_head(&skc->skc_waitq);
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;
skc->skc_obj_deadlock = 0;
skc->skc_obj_emergency = 0;
skc->skc_obj_emergency_max = 0;
/*
* Verify the requested alignment restriction is sane.
*/
if (align) {
VERIFY(ISP2(align));
VERIFY3U(align, >=, SPL_KMEM_CACHE_ALIGN);
VERIFY3U(align, <=, PAGE_SIZE);
skc->skc_obj_align = align;
}
/*
* When no specific type of slab is requested (kmem, vmem, or
* linuxslab) then select a cache type based on the object size
* and default tunables.
*/
if (!(skc->skc_flags & (KMC_KMEM | KMC_VMEM | KMC_SLAB))) {
/*
* Objects smaller than spl_kmem_cache_slab_limit can
* use the Linux slab for better space-efficiency. By
* default this functionality is disabled until its
* performance characters are fully understood.
*/
if (spl_kmem_cache_slab_limit &&
size <= (size_t)spl_kmem_cache_slab_limit)
skc->skc_flags |= KMC_SLAB;
/*
* Small objects, less than spl_kmem_cache_kmem_limit per
* object should use kmem because their slabs are small.
*/
else if (spl_obj_size(skc) <= spl_kmem_cache_kmem_limit)
skc->skc_flags |= KMC_KMEM;
/*
* All other objects are considered large and are placed
* on vmem backed slabs.
*/
else
skc->skc_flags |= KMC_VMEM;
}
/*
* Given the type of slab allocate the required resources.
*/
if (skc->skc_flags & (KMC_KMEM | KMC_VMEM)) {
rc = spl_slab_size(skc,
&skc->skc_slab_objs, &skc->skc_slab_size);
if (rc)
SGOTO(out, rc);
rc = spl_magazine_create(skc);
if (rc)
SGOTO(out, rc);
} else {
skc->skc_linux_cache = kmem_cache_create(
skc->skc_name, size, align, 0, NULL);
if (skc->skc_linux_cache == NULL)
SGOTO(out, rc = ENOMEM);
kmem_cache_set_allocflags(skc, __GFP_COMP);
skc->skc_flags |= KMC_NOMAGAZINE;
}
if (spl_kmem_cache_expire & KMC_EXPIRE_AGE)
skc->skc_taskqid = taskq_dispatch_delay(spl_kmem_cache_taskq,
spl_cache_age, skc, TQ_SLEEP,
ddi_get_lbolt() + skc->skc_delay / 3 * HZ);
down_write(&spl_kmem_cache_sem);
list_add_tail(&skc->skc_list, &spl_kmem_cache_list);
up_write(&spl_kmem_cache_sem);
SRETURN(skc);
out:
kmem_free(skc->skc_name, skc->skc_name_size);
kmem_free(skc, sizeof(*skc));
SRETURN(NULL);
}
EXPORT_SYMBOL(spl_kmem_cache_create);
/*
* Register a move callback to for cache defragmentation.
* XXX: Unimplemented but harmless to stub out for now.
*/
void
spl_kmem_cache_set_move(spl_kmem_cache_t *skc,
kmem_cbrc_t (move)(void *, void *, size_t, void *))
{
ASSERT(move != NULL);
}
EXPORT_SYMBOL(spl_kmem_cache_set_move);
/*
* Destroy a cache and all objects associated with the cache.
*/
void
spl_kmem_cache_destroy(spl_kmem_cache_t *skc)
{
DECLARE_WAIT_QUEUE_HEAD(wq);
taskqid_t id;
SENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(skc->skc_flags & (KMC_KMEM | KMC_VMEM | KMC_SLAB));
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 tasks */
VERIFY(!test_and_set_bit(KMC_BIT_DESTROY, &skc->skc_flags));
spin_lock(&skc->skc_lock);
id = skc->skc_taskqid;
spin_unlock(&skc->skc_lock);
taskq_cancel_id(spl_kmem_cache_taskq, id);
/* 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);
if (skc->skc_flags & (KMC_KMEM | KMC_VMEM)) {
spl_magazine_destroy(skc);
spl_slab_reclaim(skc, 0, 1);
} else {
ASSERT(skc->skc_flags & KMC_SLAB);
kmem_cache_destroy(skc->skc_linux_cache);
}
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);
ASSERT3U(skc->skc_obj_emergency, ==, 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));
SEXIT;
}
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;
}
/*
* Generic slab allocation function to run by the global work queues.
* It is responsible for allocating a new slab, linking it in to the list
* of partial slabs, and then waking any waiters.
*/
static void
spl_cache_grow_work(void *data)
{
spl_kmem_alloc_t *ska = (spl_kmem_alloc_t *)data;
spl_kmem_cache_t *skc = ska->ska_cache;
spl_kmem_slab_t *sks;
sks = spl_slab_alloc(skc, ska->ska_flags | __GFP_NORETRY | KM_NODEBUG);
spin_lock(&skc->skc_lock);
if (sks) {
skc->skc_slab_total++;
skc->skc_obj_total += sks->sks_objs;
list_add_tail(&sks->sks_list, &skc->skc_partial_list);
}
atomic_dec(&skc->skc_ref);
clear_bit(KMC_BIT_GROWING, &skc->skc_flags);
clear_bit(KMC_BIT_DEADLOCKED, &skc->skc_flags);
wake_up_all(&skc->skc_waitq);
spin_unlock(&skc->skc_lock);
kfree(ska);
}
/*
* Returns non-zero when a new slab should be available.
*/
static int
spl_cache_grow_wait(spl_kmem_cache_t *skc)
{
return !test_bit(KMC_BIT_GROWING, &skc->skc_flags);
}
static int
spl_cache_reclaim_wait(void *word)
{
schedule();
return 0;
}
/*
* No available objects on any slabs, create a new slab. Note that this
* functionality is disabled for KMC_SLAB caches which are backed by the
* Linux slab.
*/
static int
spl_cache_grow(spl_kmem_cache_t *skc, int flags, void **obj)
{
int remaining, rc;
SENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT((skc->skc_flags & KMC_SLAB) == 0);
might_sleep();
*obj = NULL;
/*
* Before allocating a new slab wait for any reaping to complete and
* then return so the local magazine can be rechecked for new objects.
*/
if (test_bit(KMC_BIT_REAPING, &skc->skc_flags)) {
rc = wait_on_bit(&skc->skc_flags, KMC_BIT_REAPING,
spl_cache_reclaim_wait, TASK_UNINTERRUPTIBLE);
SRETURN(rc ? rc : -EAGAIN);
}
/*
* This is handled by dispatching a work request to the global work
* queue. This allows us to asynchronously allocate a new slab while
* retaining the ability to safely fall back to a smaller synchronous
* allocations to ensure forward progress is always maintained.
*/
if (test_and_set_bit(KMC_BIT_GROWING, &skc->skc_flags) == 0) {
spl_kmem_alloc_t *ska;
ska = kmalloc(sizeof(*ska), flags);
if (ska == NULL) {
clear_bit(KMC_BIT_GROWING, &skc->skc_flags);
wake_up_all(&skc->skc_waitq);
SRETURN(-ENOMEM);
}
atomic_inc(&skc->skc_ref);
ska->ska_cache = skc;
ska->ska_flags = flags & ~__GFP_FS;
taskq_init_ent(&ska->ska_tqe);
taskq_dispatch_ent(spl_kmem_cache_taskq,
spl_cache_grow_work, ska, 0, &ska->ska_tqe);
}
/*
* The goal here is to only detect the rare case where a virtual slab
* allocation has deadlocked. We must be careful to minimize the use
* of emergency objects which are more expensive to track. Therefore,
* we set a very long timeout for the asynchronous allocation and if
* the timeout is reached the cache is flagged as deadlocked. From
* this point only new emergency objects will be allocated until the
* asynchronous allocation completes and clears the deadlocked flag.
*/
if (test_bit(KMC_BIT_DEADLOCKED, &skc->skc_flags)) {
rc = spl_emergency_alloc(skc, flags, obj);
} else {
remaining = wait_event_timeout(skc->skc_waitq,
spl_cache_grow_wait(skc), HZ);
if (!remaining && test_bit(KMC_BIT_VMEM, &skc->skc_flags)) {
spin_lock(&skc->skc_lock);
if (test_bit(KMC_BIT_GROWING, &skc->skc_flags)) {
set_bit(KMC_BIT_DEADLOCKED, &skc->skc_flags);
skc->skc_obj_deadlock++;
}
spin_unlock(&skc->skc_lock);
}
rc = -ENOMEM;
}
SRETURN(rc);
}
/*
* 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. On success NULL is returned, otherwise
* the address of a single emergency object is returned for use by the caller.
*/
static void *
spl_cache_refill(spl_kmem_cache_t *skc, spl_kmem_magazine_t *skm, int flags)
{
spl_kmem_slab_t *sks;
int count = 0, rc, refill;
void *obj = NULL;
SENTRY;
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);
local_irq_enable();
rc = spl_cache_grow(skc, flags, &obj);
local_irq_disable();
/* Emergency object for immediate use by caller */
if (rc == 0 && obj != NULL)
SRETURN(obj);
if (rc)
SGOTO(out, rc);
/* Rescheduled to different CPU skm is not local */
if (skm != skc->skc_mag[smp_processor_id()])
SGOTO(out, rc);
/* Potentially rescheduled to the same CPU but
* allocations may have occurred 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 && ++count) {
ASSERT(skm->skm_avail < skm->skm_size);
ASSERT(count < 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:
SRETURN(NULL);
}
/*
* 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;
SENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(spin_is_locked(&skc->skc_lock));
sko = spl_sko_from_obj(skc, obj);
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 empty 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--;
}
SEXIT;
}
/*
* 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;
void *obj = NULL;
SENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
ASSERT(flags & KM_SLEEP);
atomic_inc(&skc->skc_ref);
/*
* Allocate directly from a Linux slab. All optimizations are left
* to the underlying cache we only need to guarantee that KM_SLEEP
* callers will never fail.
*/
if (skc->skc_flags & KMC_SLAB) {
struct kmem_cache *slc = skc->skc_linux_cache;
do {
obj = kmem_cache_alloc(slc, flags | __GFP_COMP);
if (obj && skc->skc_ctor)
skc->skc_ctor(obj, skc->skc_private, flags);
} while ((obj == NULL) && !(flags & KM_NOSLEEP));
atomic_dec(&skc->skc_ref);
SRETURN(obj);
}
local_irq_disable();
restart:
/* Safe to update per-cpu structure without lock, but
* in the restart case we must be careful to reacquire
* 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 {
obj = spl_cache_refill(skc, skm, flags);
if (obj == NULL)
SGOTO(restart, obj = NULL);
}
local_irq_enable();
ASSERT(obj);
ASSERT(IS_P2ALIGNED(obj, skc->skc_obj_align));
/* Pre-emptively migrate object to CPU L1 cache */
prefetchw(obj);
atomic_dec(&skc->skc_ref);
SRETURN(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;
SENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
atomic_inc(&skc->skc_ref);
/*
* Free the object from the Linux underlying Linux slab.
*/
if (skc->skc_flags & KMC_SLAB) {
if (skc->skc_dtor)
skc->skc_dtor(obj, skc->skc_private);
kmem_cache_free(skc->skc_linux_cache, obj);
goto out;
}
/*
* Only virtual slabs may have emergency objects and these objects
* are guaranteed to have physical addresses. They must be removed
* from the tree of emergency objects and the freed.
*/
if ((skc->skc_flags & KMC_VMEM) && !kmem_virt(obj))
SGOTO(out, spl_emergency_free(skc, obj));
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))
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);
out:
atomic_dec(&skc->skc_ref);
SEXIT;
}
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 tries 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, which differs from Solaris semantics.
* Solaris semantics are to free all available objects which may (and
* probably will) be more objects than the requested nr_to_scan.
*/
static int
__spl_kmem_cache_generic_shrinker(struct shrinker *shrink,
struct shrink_control *sc)
{
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 (sc->nr_to_scan)
spl_kmem_cache_reap_now(skc,
MAX(sc->nr_to_scan >> fls64(skc->skc_slab_objs), 1));
/*
* 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);
/*
* After performing reclaim always return -1 to indicate we cannot
* perform additional reclaim. This prevents shrink_slabs() from
* repeatedly invoking this generic shrinker and potentially spinning.
*/
if (sc->nr_to_scan)
return -1;
return unused;
}
SPL_SHRINKER_CALLBACK_WRAPPER(spl_kmem_cache_generic_shrinker);
/*
* 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, int count)
{
SENTRY;
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
atomic_inc(&skc->skc_ref);
/*
* Execute the registered reclaim callback if it exists. The
* per-cpu caches will be drained when is set KMC_EXPIRE_MEM.
*/
if (skc->skc_flags & KMC_SLAB) {
if (skc->skc_reclaim)
skc->skc_reclaim(skc->skc_private);
if (spl_kmem_cache_expire & KMC_EXPIRE_MEM)
kmem_cache_shrink(skc->skc_linux_cache);
SGOTO(out, 0);
}
/*
* Prevent concurrent cache reaping when contended.
*/
if (test_and_set_bit(KMC_BIT_REAPING, &skc->skc_flags))
SGOTO(out, 0);
/*
* When a reclaim function is available it may be invoked repeatedly
* until at least a single slab can be freed. This ensures that we
* do free memory back to the system. This helps minimize the chance
* of an OOM event when the bulk of memory is used by the slab.
*
* When free slabs are already available the reclaim callback will be
* skipped. Additionally, if no forward progress is detected despite
* a reclaim function the cache will be skipped to avoid deadlock.
*
* Longer term this would be the correct place to add the code which
* repacks the slabs in order minimize fragmentation.
*/
if (skc->skc_reclaim) {
uint64_t objects = UINT64_MAX;
int do_reclaim;
do {
spin_lock(&skc->skc_lock);
do_reclaim =
(skc->skc_slab_total > 0) &&
((skc->skc_slab_total - skc->skc_slab_alloc) == 0) &&
(skc->skc_obj_alloc < objects);
objects = skc->skc_obj_alloc;
spin_unlock(&skc->skc_lock);
if (do_reclaim)
skc->skc_reclaim(skc->skc_private);
} while (do_reclaim);
}
/* Reclaim from the magazine then the slabs ignoring age and delay. */
if (spl_kmem_cache_expire & KMC_EXPIRE_MEM) {
spl_kmem_magazine_t *skm;
unsigned long irq_flags;
local_irq_save(irq_flags);
skm = skc->skc_mag[smp_processor_id()];
spl_cache_flush(skc, skm, skm->skm_avail);
local_irq_restore(irq_flags);
}
spl_slab_reclaim(skc, count, 1);
clear_bit(KMC_BIT_REAPING, &skc->skc_flags);
smp_mb__after_clear_bit();
wake_up_bit(&skc->skc_flags, KMC_BIT_REAPING);
out:
atomic_dec(&skc->skc_ref);
SEXIT;
}
EXPORT_SYMBOL(spl_kmem_cache_reap_now);
/*
* Reap all free slabs from all registered caches.
*/
void
spl_kmem_reap(void)
{
struct shrink_control sc;
sc.nr_to_scan = KMC_REAP_CHUNK;
sc.gfp_mask = GFP_KERNEL;
__spl_kmem_cache_generic_shrinker(NULL, &sc);
}
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;
SENTRY;
spin_lock_init(lock);
INIT_LIST_HEAD(list);
for (i = 0; i < size; i++)
INIT_HLIST_HEAD(&kmem_table[i]);
SRETURN(0);
}
static void
spl_kmem_fini_tracking(struct list_head *list, spinlock_t *lock)
{
unsigned long flags;
kmem_debug_t *kd;
char str[17];
SENTRY;
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);
SEXIT;
}
#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 */
static void
spl_kmem_init_globals(void)
{
struct zone *zone;
/* For now all zones are includes, it may be wise to restrict
* this to normal and highmem zones if we see problems. */
for_each_zone(zone) {
if (!populated_zone(zone))
continue;
minfree += min_wmark_pages(zone);
desfree += low_wmark_pages(zone);
lotsfree += high_wmark_pages(zone);
}
/* Solaris default values */
swapfs_minfree = MAX(2*1024*1024 >> PAGE_SHIFT, physmem >> 3);
swapfs_reserve = MIN(4*1024*1024 >> PAGE_SHIFT, physmem >> 4);
}
/*
* Called at module init when it is safe to use spl_kallsyms_lookup_name()
*/
int
spl_kmem_init_kallsyms_lookup(void)
{
#ifndef HAVE_GET_VMALLOC_INFO
get_vmalloc_info_fn = (get_vmalloc_info_t)
spl_kallsyms_lookup_name("get_vmalloc_info");
if (!get_vmalloc_info_fn) {
printk(KERN_ERR "Error: Unknown symbol get_vmalloc_info\n");
return -EFAULT;
}
#endif /* HAVE_GET_VMALLOC_INFO */
#ifdef HAVE_PGDAT_HELPERS
# ifndef HAVE_FIRST_ONLINE_PGDAT
first_online_pgdat_fn = (first_online_pgdat_t)
spl_kallsyms_lookup_name("first_online_pgdat");
if (!first_online_pgdat_fn) {
printk(KERN_ERR "Error: Unknown symbol first_online_pgdat\n");
return -EFAULT;
}
# endif /* HAVE_FIRST_ONLINE_PGDAT */
# ifndef HAVE_NEXT_ONLINE_PGDAT
next_online_pgdat_fn = (next_online_pgdat_t)
spl_kallsyms_lookup_name("next_online_pgdat");
if (!next_online_pgdat_fn) {
printk(KERN_ERR "Error: Unknown symbol next_online_pgdat\n");
return -EFAULT;
}
# endif /* HAVE_NEXT_ONLINE_PGDAT */
# ifndef HAVE_NEXT_ZONE
next_zone_fn = (next_zone_t)
spl_kallsyms_lookup_name("next_zone");
if (!next_zone_fn) {
printk(KERN_ERR "Error: Unknown symbol next_zone\n");
return -EFAULT;
}
# endif /* HAVE_NEXT_ZONE */
#else /* HAVE_PGDAT_HELPERS */
# ifndef HAVE_PGDAT_LIST
pgdat_list_addr = *(struct pglist_data **)
spl_kallsyms_lookup_name("pgdat_list");
if (!pgdat_list_addr) {
printk(KERN_ERR "Error: Unknown symbol pgdat_list\n");
return -EFAULT;
}
# endif /* HAVE_PGDAT_LIST */
#endif /* HAVE_PGDAT_HELPERS */
#if defined(NEED_GET_ZONE_COUNTS) && !defined(HAVE_GET_ZONE_COUNTS)
get_zone_counts_fn = (get_zone_counts_t)
spl_kallsyms_lookup_name("get_zone_counts");
if (!get_zone_counts_fn) {
printk(KERN_ERR "Error: Unknown symbol get_zone_counts\n");
return -EFAULT;
}
#endif /* NEED_GET_ZONE_COUNTS && !HAVE_GET_ZONE_COUNTS */
/*
* It is now safe to initialize the global tunings which rely on
* the use of the for_each_zone() macro. This macro in turns
* depends on the *_pgdat symbols which are now available.
*/
spl_kmem_init_globals();
#ifndef HAVE_SHRINK_DCACHE_MEMORY
/* When shrink_dcache_memory_fn == NULL support is disabled */
shrink_dcache_memory_fn = (shrink_dcache_memory_t)
spl_kallsyms_lookup_name("shrink_dcache_memory");
#endif /* HAVE_SHRINK_DCACHE_MEMORY */
#ifndef HAVE_SHRINK_ICACHE_MEMORY
/* When shrink_icache_memory_fn == NULL support is disabled */
shrink_icache_memory_fn = (shrink_icache_memory_t)
spl_kallsyms_lookup_name("shrink_icache_memory");
#endif /* HAVE_SHRINK_ICACHE_MEMORY */
return 0;
}
int
spl_kmem_init(void)
{
int rc = 0;
SENTRY;
#ifdef DEBUG_KMEM
kmem_alloc_used_set(0);
vmem_alloc_used_set(0);
spl_kmem_init_tracking(&kmem_list, &kmem_lock, KMEM_TABLE_SIZE);
spl_kmem_init_tracking(&vmem_list, &vmem_lock, VMEM_TABLE_SIZE);
#endif
init_rwsem(&spl_kmem_cache_sem);
INIT_LIST_HEAD(&spl_kmem_cache_list);
spl_kmem_cache_taskq = taskq_create("spl_kmem_cache",
1, maxclsyspri, 1, 32, TASKQ_PREPOPULATE);
spl_register_shrinker(&spl_kmem_cache_shrinker);
SRETURN(rc);
}
void
spl_kmem_fini(void)
{
SENTRY;
spl_unregister_shrinker(&spl_kmem_cache_shrinker);
taskq_destroy(spl_kmem_cache_taskq);
#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 (kmem_alloc_used_read() != 0)
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING,
"kmem leaked %ld/%ld bytes\n",
kmem_alloc_used_read(), kmem_alloc_max);
if (vmem_alloc_used_read() != 0)
SDEBUG_LIMIT(SD_CONSOLE | SD_WARNING,
"vmem leaked %ld/%ld bytes\n",
vmem_alloc_used_read(), vmem_alloc_max);
spl_kmem_fini_tracking(&kmem_list, &kmem_lock);
spl_kmem_fini_tracking(&vmem_list, &vmem_lock);
#endif /* DEBUG_KMEM */
SEXIT;
}
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