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author | Jennifer Averett <jennifer.averett@oarcorp.com> | 2012-11-26 09:47:09 -0600 |
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committer | Jennifer Averett <jennifer.averett@oarcorp.com> | 2012-11-26 09:47:09 -0600 |
commit | 0bde19eee050bbdc4511070cf14f48719e400c26 (patch) | |
tree | d7bf926c193da25600c5612fe25070c5133d9979 /freebsd/kern/kern_mtxpool.c | |
parent | Add custom limits.h and timespec.h (diff) | |
download | rtems-libbsd-0bde19eee050bbdc4511070cf14f48719e400c26.tar.bz2 |
Switch to a version of select that is closer to bsd's version.
Diffstat (limited to 'freebsd/kern/kern_mtxpool.c')
-rw-r--r-- | freebsd/kern/kern_mtxpool.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/freebsd/kern/kern_mtxpool.c b/freebsd/kern/kern_mtxpool.c new file mode 100644 index 00000000..b2c0267a --- /dev/null +++ b/freebsd/kern/kern_mtxpool.c @@ -0,0 +1,220 @@ +#include <freebsd/machine/rtems-bsd-config.h> + +/*- + * Copyright (c) 2001 Matthew Dillon. All Rights Reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* Mutex pool routines. These routines are designed to be used as short + * term leaf mutexes (e.g. the last mutex you might acquire other then + * calling msleep()). They operate using a shared pool. A mutex is chosen + * from the pool based on the supplied pointer (which may or may not be + * valid). + * + * Advantages: + * - no structural overhead. Mutexes can be associated with structures + * without adding bloat to the structures. + * - mutexes can be obtained for invalid pointers, useful when uses + * mutexes to interlock destructor ops. + * - no initialization/destructor overhead. + * - can be used with msleep. + * + * Disadvantages: + * - should generally only be used as leaf mutexes. + * - pool/pool dependancy ordering cannot be depended on. + * - possible L1 cache mastersip contention between cpus. + */ + +#include <freebsd/sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <freebsd/sys/param.h> +#include <freebsd/sys/proc.h> +#include <freebsd/sys/kernel.h> +#include <freebsd/sys/ktr.h> +#include <freebsd/sys/lock.h> +#include <freebsd/sys/malloc.h> +#include <freebsd/sys/mutex.h> +#include <freebsd/sys/systm.h> + + +static MALLOC_DEFINE(M_MTXPOOL, "mtx_pool", "mutex pool"); + +/* Pool sizes must be a power of two */ +#ifndef MTX_POOL_LOCKBUILDER_SIZE +#define MTX_POOL_LOCKBUILDER_SIZE 128 +#endif +#ifndef MTX_POOL_SLEEP_SIZE +#define MTX_POOL_SLEEP_SIZE 128 +#endif + +struct mtxpool_header { + int mtxpool_size; + int mtxpool_mask; + int mtxpool_shift; + int mtxpool_next; +}; + +struct mtx_pool { + struct mtxpool_header mtx_pool_header; + struct mtx mtx_pool_ary[1]; +}; + +static struct mtx_pool_lockbuilder { + struct mtxpool_header mtx_pool_header; + struct mtx mtx_pool_ary[MTX_POOL_LOCKBUILDER_SIZE]; +} lockbuilder_pool; + +#define mtx_pool_size mtx_pool_header.mtxpool_size +#define mtx_pool_mask mtx_pool_header.mtxpool_mask +#define mtx_pool_shift mtx_pool_header.mtxpool_shift +#define mtx_pool_next mtx_pool_header.mtxpool_next + +struct mtx_pool *mtxpool_sleep; +struct mtx_pool *mtxpool_lockbuilder; + +#if UINTPTR_MAX == UINT64_MAX /* 64 bits */ +# define POINTER_BITS 64 +# define HASH_MULTIPLIER 11400714819323198485u /* (2^64)*(sqrt(5)-1)/2 */ +#else /* assume 32 bits */ +# define POINTER_BITS 32 +# define HASH_MULTIPLIER 2654435769u /* (2^32)*(sqrt(5)-1)/2 */ +#endif + +/* + * Return the (shared) pool mutex associated with the specified address. + * The returned mutex is a leaf level mutex, meaning that if you obtain it + * you cannot obtain any other mutexes until you release it. You can + * legally msleep() on the mutex. + */ +struct mtx * +mtx_pool_find(struct mtx_pool *pool, void *ptr) +{ + int p; + + KASSERT(pool != NULL, ("_mtx_pool_find(): null pool")); + /* + * Fibonacci hash, see Knuth's + * _Art of Computer Programming, Volume 3 / Sorting and Searching_ + */ + p = ((HASH_MULTIPLIER * (uintptr_t)ptr) >> pool->mtx_pool_shift) & + pool->mtx_pool_mask; + return (&pool->mtx_pool_ary[p]); +} + +static void +mtx_pool_initialize(struct mtx_pool *pool, const char *mtx_name, int pool_size, + int opts) +{ + int i, maskbits; + + pool->mtx_pool_size = pool_size; + pool->mtx_pool_mask = pool_size - 1; + for (i = 1, maskbits = 0; (i & pool_size) == 0; i = i << 1) + maskbits++; + pool->mtx_pool_shift = POINTER_BITS - maskbits; + pool->mtx_pool_next = 0; + for (i = 0; i < pool_size; ++i) + mtx_init(&pool->mtx_pool_ary[i], mtx_name, NULL, opts); +} + +struct mtx_pool * +mtx_pool_create(const char *mtx_name, int pool_size, int opts) +{ + struct mtx_pool *pool; + + if (pool_size <= 0 || !powerof2(pool_size)) { + printf("WARNING: %s pool size is not a power of 2.\n", + mtx_name); + pool_size = 128; + } + pool = malloc(sizeof (struct mtx_pool) + + ((pool_size - 1) * sizeof (struct mtx)), + M_MTXPOOL, M_WAITOK | M_ZERO); + mtx_pool_initialize(pool, mtx_name, pool_size, opts); + return pool; +} + +void +mtx_pool_destroy(struct mtx_pool **poolp) +{ + int i; + struct mtx_pool *pool = *poolp; + + for (i = pool->mtx_pool_size - 1; i >= 0; --i) + mtx_destroy(&pool->mtx_pool_ary[i]); + free(pool, M_MTXPOOL); + *poolp = NULL; +} + +static void +mtx_pool_setup_static(void *dummy __unused) +{ + mtx_pool_initialize((struct mtx_pool *)&lockbuilder_pool, + "lockbuilder mtxpool", MTX_POOL_LOCKBUILDER_SIZE, + MTX_DEF | MTX_NOWITNESS | MTX_QUIET); + mtxpool_lockbuilder = (struct mtx_pool *)&lockbuilder_pool; +} + +static void +mtx_pool_setup_dynamic(void *dummy __unused) +{ + mtxpool_sleep = mtx_pool_create("sleep mtxpool", + MTX_POOL_SLEEP_SIZE, MTX_DEF); +} + +/* + * Obtain a (shared) mutex from the pool. The returned mutex is a leaf + * level mutex, meaning that if you obtain it you cannot obtain any other + * mutexes until you release it. You can legally msleep() on the mutex. + */ +struct mtx * +mtx_pool_alloc(struct mtx_pool *pool) +{ + int i; + + KASSERT(pool != NULL, ("mtx_pool_alloc(): null pool")); + /* + * mtx_pool_next is unprotected against multiple accesses, + * but simultaneous access by two CPUs should not be very + * harmful. + */ + i = pool->mtx_pool_next; + pool->mtx_pool_next = (i + 1) & pool->mtx_pool_mask; + return (&pool->mtx_pool_ary[i]); +} + +/* + * The lockbuilder pool must be initialized early because the lockmgr + * and sx locks depend on it. The sx locks are used in the kernel + * memory allocator. The lockmgr subsystem is initialized by + * SYSINIT(..., SI_SUB_LOCKMGR, ...). + * + * We can't call malloc() to dynamically allocate the sleep pool + * until after kmeminit() has been called, which is done by + * SYSINIT(..., SI_SUB_KMEM, ...). + */ +SYSINIT(mtxpooli1, SI_SUB_MTX_POOL_STATIC, SI_ORDER_FIRST, + mtx_pool_setup_static, NULL); +SYSINIT(mtxpooli2, SI_SUB_MTX_POOL_DYNAMIC, SI_ORDER_FIRST, + mtx_pool_setup_dynamic, NULL); |