[lttng-tools.git] / src / common / hashtable / rculfhash-mm-mmap.c

/*
 * rculfhash-mm-mmap.c
 *
 * mmap/reservation based memory management for Lock-Free RCU Hash Table
 *
 * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <unistd.h>
#include <sys/mman.h>
#include "rculfhash-internal.h"

/* reserve inaccessible memory space without allocation any memory */
static void *memory_map(size_t length)
{
	void *ret = mmap(NULL, length, PROT_NONE,
			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

	assert(ret != MAP_FAILED);
	return ret;
}

static void memory_unmap(void *ptr, size_t length)
{
	int ret __attribute__((unused));

	ret = munmap(ptr, length);

	assert(ret == 0);
}

static void memory_populate(void *ptr, size_t length)
{
	void *ret __attribute__((unused));

	ret = mmap(ptr, length, PROT_READ | PROT_WRITE,
			MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

	assert(ret == ptr);
}

/*
 * Discard garbage memory and avoid system save it when try to swap it out.
 * Make it still reserved, inaccessible.
 */
static void memory_discard(void *ptr, size_t length)
{
	void *ret __attribute__((unused));

	ret = mmap(ptr, length, PROT_NONE,
			MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

	assert(ret == ptr);
}

static
void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order)
{
	if (order == 0) {
		if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) {
			/* small table */
			ht->tbl_mmap = calloc(ht->max_nr_buckets,
					sizeof(*ht->tbl_mmap));
			assert(ht->tbl_mmap);
			return;
		}
		/* large table */
		ht->tbl_mmap = memory_map(ht->max_nr_buckets
			* sizeof(*ht->tbl_mmap));
		memory_populate(ht->tbl_mmap,
			ht->min_nr_alloc_buckets * sizeof(*ht->tbl_mmap));
	} else if (order > ht->min_alloc_buckets_order) {
		/* large table */
		unsigned long len = 1UL << (order - 1);

		assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets);
		memory_populate(ht->tbl_mmap + len,
				len * sizeof(*ht->tbl_mmap));
	}
	/* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
}

/*
 * cds_lfht_free_bucket_table() should be called with decreasing order.
 * When cds_lfht_free_bucket_table(0) is called, it means the whole
 * lfht is destroyed.
 */
static
void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
{
	if (order == 0) {
		if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) {
			/* small table */
			poison_free(ht->tbl_mmap);
			return;
		}
		/* large table */
		memory_unmap(ht->tbl_mmap,
			ht->max_nr_buckets * sizeof(*ht->tbl_mmap));
	} else if (order > ht->min_alloc_buckets_order) {
		/* large table */
		unsigned long len = 1UL << (order - 1);

		assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets);
		memory_discard(ht->tbl_mmap + len, len * sizeof(*ht->tbl_mmap));
	}
	/* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
}

static
struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
{
	return &ht->tbl_mmap[index];
}

static
struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets,
		unsigned long max_nr_buckets)
{
	unsigned long page_bucket_size;

	page_bucket_size = getpagesize() / sizeof(struct cds_lfht_node);
	if (max_nr_buckets <= page_bucket_size) {
		/* small table */
		min_nr_alloc_buckets = max_nr_buckets;
	} else {
		/* large table */
		min_nr_alloc_buckets = max(min_nr_alloc_buckets,
					page_bucket_size);
	}

	return __default_alloc_cds_lfht(
			&cds_lfht_mm_mmap, sizeof(struct cds_lfht),
			min_nr_alloc_buckets, max_nr_buckets);
}

const struct cds_lfht_mm_type cds_lfht_mm_mmap = {
	.alloc_cds_lfht = alloc_cds_lfht,
	.alloc_bucket_table = cds_lfht_alloc_bucket_table,
	.free_bucket_table = cds_lfht_free_bucket_table,
	.bucket_at = bucket_at,
};
Commit	Line	Data
bec39940 DG	1	/*
	2	* rculfhash-mm-mmap.c
	3	*
	4	* mmap/reservation based memory management for Lock-Free RCU Hash Table
	5	*
	6	* Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
	7	*
	8	* This library is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU Lesser General Public
	10	* License as published by the Free Software Foundation; either
	11	* version 2.1 of the License, or (at your option) any later version.
	12	*
	13	* This library is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	16	* Lesser General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU Lesser General Public
	19	* License along with this library; if not, write to the Free Software
	20	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	21	*/
	22
	23	#include <unistd.h>
	24	#include <sys/mman.h>
	25	#include "rculfhash-internal.h"
	26
	27	/* reserve inaccessible memory space without allocation any memory */
	28	static void *memory_map(size_t length)
	29	{
	30	void *ret = mmap(NULL, length, PROT_NONE,
	31	MAP_PRIVATE \| MAP_ANONYMOUS, -1, 0);
	32
	33	assert(ret != MAP_FAILED);
	34	return ret;
	35	}
	36
	37	static void memory_unmap(void *ptr, size_t length)
	38	{
	39	int ret __attribute__((unused));
	40
	41	ret = munmap(ptr, length);
	42
	43	assert(ret == 0);
	44	}
	45
	46	static void memory_populate(void *ptr, size_t length)
	47	{
	48	void *ret __attribute__((unused));
	49
	50	ret = mmap(ptr, length, PROT_READ \| PROT_WRITE,
	51	MAP_FIXED \| MAP_PRIVATE \| MAP_ANONYMOUS, -1, 0);
	52
	53	assert(ret == ptr);
	54	}
	55
	56	/*
	57	* Discard garbage memory and avoid system save it when try to swap it out.
	58	* Make it still reserved, inaccessible.
	59	*/
	60	static void memory_discard(void *ptr, size_t length)
	61	{
	62	void *ret __attribute__((unused));
	63
	64	ret = mmap(ptr, length, PROT_NONE,
65	MAP_FIXED \| MAP_PRIVATE \| MAP_ANONYMOUS, -1, 0);
66
67	assert(ret == ptr);
68	}
69
70	static
71	void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order)
72	{
73	if (order == 0) {
74	if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) {
75	/* small table */
76	ht->tbl_mmap = calloc(ht->max_nr_buckets,
77	sizeof(*ht->tbl_mmap));
78	assert(ht->tbl_mmap);
79	return;
80	}
81	/* large table */
82	ht->tbl_mmap = memory_map(ht->max_nr_buckets
83	* sizeof(*ht->tbl_mmap));
84	memory_populate(ht->tbl_mmap,
85	ht->min_nr_alloc_buckets * sizeof(*ht->tbl_mmap));
86	} else if (order > ht->min_alloc_buckets_order) {
87	/* large table */
88	unsigned long len = 1UL << (order - 1);
89
90	assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets);
91	memory_populate(ht->tbl_mmap + len,
92	len * sizeof(*ht->tbl_mmap));
93	}
94	/* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
95	}
96
97	/*
98	* cds_lfht_free_bucket_table() should be called with decreasing order.
99	* When cds_lfht_free_bucket_table(0) is called, it means the whole
100	* lfht is destroyed.
101	*/
102	static
103	void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
104	{
105	if (order == 0) {
106	if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) {
107	/* small table */
108	poison_free(ht->tbl_mmap);
109	return;
110	}
111	/* large table */
112	memory_unmap(ht->tbl_mmap,
113	ht->max_nr_buckets * sizeof(*ht->tbl_mmap));
114	} else if (order > ht->min_alloc_buckets_order) {
115	/* large table */
116	unsigned long len = 1UL << (order - 1);
117
118	assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets);
119	memory_discard(ht->tbl_mmap + len, len * sizeof(*ht->tbl_mmap));
120	}
121	/* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
122	}
123
124	static
125	struct cds_lfht_node bucket_at(struct cds_lfht ht, unsigned long index)
126	{
127	return &ht->tbl_mmap[index];
128	}
129
130	static
131	struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets,
132	unsigned long max_nr_buckets)
133	{
134	unsigned long page_bucket_size;
135
136	page_bucket_size = getpagesize() / sizeof(struct cds_lfht_node);
137	if (max_nr_buckets <= page_bucket_size) {
138	/* small table */
139	min_nr_alloc_buckets = max_nr_buckets;
140	} else {
141	/* large table */
142	min_nr_alloc_buckets = max(min_nr_alloc_buckets,
143	page_bucket_size);
144	}
145
146	return __default_alloc_cds_lfht(
147	&cds_lfht_mm_mmap, sizeof(struct cds_lfht),
148	min_nr_alloc_buckets, max_nr_buckets);
149	}
150
151	const struct cds_lfht_mm_type cds_lfht_mm_mmap = {
152	.alloc_cds_lfht = alloc_cds_lfht,
153	.alloc_bucket_table = cds_lfht_alloc_bucket_table,
154	.free_bucket_table = cds_lfht_free_bucket_table,
155	.bucket_at = bucket_at,
156	};