POOL_CACHE(9) | Kernel Developer's Manual | POOL_CACHE(9) |
pool_cache
, pool_cache_init
,
pool_cache_destroy
,
pool_cache_get_paddr
,
pool_cache_get
,
pool_cache_put_paddr
,
pool_cache_put
,
pool_cache_destruct_object
,
pool_cache_invalidate
,
pool_cache_sethiwat
,
pool_cache_setlowat
,
pool_cache_sethardlimit
—
#include <sys/pool.h>
pool_cache_t
pool_cache_init
(size_t
size, u_int align,
u_int align_offset,
int flags,
const char *name,
struct pool_allocator
*palloc, int ipl,
int (*ctor)(void *, void *,
int), void (*dtor)(void
*, void *), void
*arg);
void
pool_cache_destroy
(pool_cache_t
pc);
void *
pool_cache_get_paddr
(pool_cache_t
pc, int flags,
paddr_t *pap);
void *
pool_cache_get
(pool_cache_t
pc, int flags);
void
pool_cache_put_paddr
(pool_cache_t
pc, void *object,
paddr_t pa);
void
pool_cache_put
(pool_cache_t
pc, void
*object);
void
pool_cache_destruct_object
(pool_cache_t
pc, void
*object);
void
pool_cache_invalidate
(pool_cache_t
pc);
void
pool_cache_sethiwat
(pool_cache_t
pc, int n);
void
pool_cache_setlowat
(pool_cache_t
pc, int n);
void
pool_cache_sethardlimit
(pool_cache_t
pc, int n,
const char *warnmess,
int ratecap);
pool_cache
follows the
pool(9) API closely and offers
routines that are functionally equivalent to their
pool(9) counterparts. In
addition, pool_cache
provides object management
functions used to manipulate objects allocated from the pool. It also
maintains global and per-CPU caches, both levels of cache work together to
allow for low overhead allocation and release of objects, and improved
L1/L2/L3 hardware cache locality in multiprocessor systems.
pool_cache_init
(size,
align, align_offset,
flags, name,
palloc, ipl,
ctor, dtor,
arg)Allocate and initialize a pool cache. The arguments are:
Specifies the size of the memory items managed by the pool.
Specifies the memory address alignment of the items
returned by pool_cache_get
(). This argument
must be a power of two. If zero, the alignment defaults to an
architecture-specific natural alignment.
The offset within an item to which the align parameter applies.
Should be set to zero, PR_NOTOUCH
,
or PR_PSERIALIZE
. If
PR_NOTOUCH
is given, free items are never
used to keep internal state so that the pool can be used for non
memory backed objects. If PR_PSERIALIZE
is
given, then the allocator guarantees that a passive serialization
barrier equivalent to “xc_barrier(0)” will be
performed before either the object's destructor is called or before
object's backing store is returned to the system.
PR_PSERIALIZE
implies
PR_NOTOUCH
. Because of the guarantees
provided by PR_PSERIALIZE
, objects must
never be freed to a pool cache using this option from either hard or
soft interrupt context, as doing so may block.
The name used to identify the object in diagnostic output.
Should be typically be set to NULL, instructing
pool_cache_init
() to select an appropriate
back-end allocator. Alternate allocators can be used to partition
space from arbitrary sources. Use of alternate allocators is not
documented here as it is not a stable, endorsed part of the API.
Specifies an interrupt priority level that will block all
interrupt handlers that could potentially access the pool. The
pool_cache
facility provides its own
synchronization. The users of any given
pool_cache
need not provide additional
synchronization for access to it.
Specifies a constructor used to initialize newly allocated
objects. If no constructor is required, specify
NULL
. The first argument to
ctor is arg, the second
is the new object, and the third is flags.
Specifies a destructor used to destroy cached objects
prior to their release to backing store. If no destructor is
required, specify NULL
. The first argument
to dtor is arg, and the
second is the object.
This value of this argument will be passed to both the constructor and destructor routines.
pool_cache_destroy
(pc)Destroy a pool cache pc. All other access to the cache must be stopped before this call can be made.
pool_cache_get_paddr
(pc,
flags, pap)Get an object from a pool cache pc. If
pap is not NULL
, physical
address of the object or POOL_PADDR_INVALID
will
be returned via it. flags will be passed to
pool_get
() function of the backing
pool(9) and the object
constructor specified when the pool cache is created by
pool_cache_init
().
pool_cache_get
(pc,
flags)pool_cache_get
() is the same as
pool_cache_get_paddr
() with
NULL
pap argument. It's
implemented as a macro.
pool_cache_put_paddr
(pc,
object, pa)Put an object object back to the pool
cache pc. pa should be
physical address of the object object or
POOL_PADDR_INVALID
. If the number of available
items in the backing pool exceeds the maximum pool size set by
pool_cache_sethiwat
() and there are no
outstanding requests for pool items, the excess items will be returned
to the system.
pool_cache_put
(pc,
object)pool_cache_put
() is the same as
pool_cache_put_paddr
() with
POOL_PADDR_INVALID
pa
argument. It's implemented as a macro.
pool_cache_destruct_object
(pc,
object)Force destruction of an object object and release it back into the pool.
pool_cache_invalidate
(pc)Invalidate a pool cache pc. All objects in the cache will be destructed and freed back to the pool backing the cache. For pool caches that vend constructed objects, consumers of this API must take care to provide proper synchronization between the input to the constructor and cache invalidation.
pool_cache_sethiwat
(pc,
n)A pool will attempt to increase its resource usage to keep up with the demand for its items. Conversely, it will return unused memory to the system should the number of accumulated free items in the pool exceed a programmable limit. The limits for the minimum and maximum number of free items which a pool should try to keep available are known as the high and low watermarks.
The function pool_cache_sethiwat
()
sets the backing pool's high water mark. As items are freed and the
number of free items in the pool is larger than the maximum set by this
function, any completely unused pages are released immediately. If this
function is not used to specify a maximum number of items, the pages
will remain associated with the pool until the system runs low on
memory, at which point the VM system will try to reclaim unused
pages.
pool_cache_setlowat
(pc,
n)Set the minimum number of free items to try to keep in the pool. When the number of free items in the pool drops below this threshold, a non-blocking attempt is made to allocate memory for more items. The number of free items is not guaranteed to remain above this threshold.
pool_cache_sethardlimit
(pc,
n, warnmess,
ratecap)pool_cache_prime
(pc,
n)pool_cache
subsystem is implemented within the file
sys/kern/subr_pool.c.
December 21, 2021 | NetBSD 10.1 |