malloc_elem.c revision 8be94df6
1/*-
2 *   BSD LICENSE
3 *
4 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
5 *   All rights reserved.
6 *
7 *   Redistribution and use in source and binary forms, with or without
8 *   modification, are permitted provided that the following conditions
9 *   are met:
10 *
11 *     * Redistributions of source code must retain the above copyright
12 *       notice, this list of conditions and the following disclaimer.
13 *     * Redistributions in binary form must reproduce the above copyright
14 *       notice, this list of conditions and the following disclaimer in
15 *       the documentation and/or other materials provided with the
16 *       distribution.
17 *     * Neither the name of Intel Corporation nor the names of its
18 *       contributors may be used to endorse or promote products derived
19 *       from this software without specific prior written permission.
20 *
21 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
24 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
25 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
27 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
31 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33#include <stdint.h>
34#include <stddef.h>
35#include <stdio.h>
36#include <string.h>
37#include <sys/queue.h>
38
39#include <rte_memory.h>
40#include <rte_eal.h>
41#include <rte_launch.h>
42#include <rte_per_lcore.h>
43#include <rte_lcore.h>
44#include <rte_debug.h>
45#include <rte_common.h>
46#include <rte_spinlock.h>
47
48#include "malloc_elem.h"
49#include "malloc_heap.h"
50
51#define MIN_DATA_SIZE (RTE_CACHE_LINE_SIZE)
52
53/*
54 * initialise a general malloc_elem header structure
55 */
56void
57malloc_elem_init(struct malloc_elem *elem,
58		struct malloc_heap *heap, const struct rte_memseg *ms, size_t size)
59{
60	elem->heap = heap;
61	elem->ms = ms;
62	elem->prev = NULL;
63	memset(&elem->free_list, 0, sizeof(elem->free_list));
64	elem->state = ELEM_FREE;
65	elem->size = size;
66	elem->pad = 0;
67	set_header(elem);
68	set_trailer(elem);
69}
70
71/*
72 * initialise a dummy malloc_elem header for the end-of-memseg marker
73 */
74void
75malloc_elem_mkend(struct malloc_elem *elem, struct malloc_elem *prev)
76{
77	malloc_elem_init(elem, prev->heap, prev->ms, 0);
78	elem->prev = prev;
79	elem->state = ELEM_BUSY; /* mark busy so its never merged */
80}
81
82/*
83 * calculate the starting point of where data of the requested size
84 * and alignment would fit in the current element. If the data doesn't
85 * fit, return NULL.
86 */
87static void *
88elem_start_pt(struct malloc_elem *elem, size_t size, unsigned align,
89		size_t bound)
90{
91	const size_t bmask = ~(bound - 1);
92	uintptr_t end_pt = (uintptr_t)elem +
93			elem->size - MALLOC_ELEM_TRAILER_LEN;
94	uintptr_t new_data_start = RTE_ALIGN_FLOOR((end_pt - size), align);
95	uintptr_t new_elem_start;
96
97	/* check boundary */
98	if ((new_data_start & bmask) != ((end_pt - 1) & bmask)) {
99		end_pt = RTE_ALIGN_FLOOR(end_pt, bound);
100		new_data_start = RTE_ALIGN_FLOOR((end_pt - size), align);
101		if (((end_pt - 1) & bmask) != (new_data_start & bmask))
102			return NULL;
103	}
104
105	new_elem_start = new_data_start - MALLOC_ELEM_HEADER_LEN;
106
107	/* if the new start point is before the exist start, it won't fit */
108	return (new_elem_start < (uintptr_t)elem) ? NULL : (void *)new_elem_start;
109}
110
111/*
112 * use elem_start_pt to determine if we get meet the size and
113 * alignment request from the current element
114 */
115int
116malloc_elem_can_hold(struct malloc_elem *elem, size_t size,	unsigned align,
117		size_t bound)
118{
119	return elem_start_pt(elem, size, align, bound) != NULL;
120}
121
122/*
123 * split an existing element into two smaller elements at the given
124 * split_pt parameter.
125 */
126static void
127split_elem(struct malloc_elem *elem, struct malloc_elem *split_pt)
128{
129	struct malloc_elem *next_elem = RTE_PTR_ADD(elem, elem->size);
130	const size_t old_elem_size = (uintptr_t)split_pt - (uintptr_t)elem;
131	const size_t new_elem_size = elem->size - old_elem_size;
132
133	malloc_elem_init(split_pt, elem->heap, elem->ms, new_elem_size);
134	split_pt->prev = elem;
135	next_elem->prev = split_pt;
136	elem->size = old_elem_size;
137	set_trailer(elem);
138}
139
140/*
141 * Given an element size, compute its freelist index.
142 * We free an element into the freelist containing similarly-sized elements.
143 * We try to allocate elements starting with the freelist containing
144 * similarly-sized elements, and if necessary, we search freelists
145 * containing larger elements.
146 *
147 * Example element size ranges for a heap with five free lists:
148 *   heap->free_head[0] - (0   , 2^8]
149 *   heap->free_head[1] - (2^8 , 2^10]
150 *   heap->free_head[2] - (2^10 ,2^12]
151 *   heap->free_head[3] - (2^12, 2^14]
152 *   heap->free_head[4] - (2^14, MAX_SIZE]
153 */
154size_t
155malloc_elem_free_list_index(size_t size)
156{
157#define MALLOC_MINSIZE_LOG2   8
158#define MALLOC_LOG2_INCREMENT 2
159
160	size_t log2;
161	size_t index;
162
163	if (size <= (1UL << MALLOC_MINSIZE_LOG2))
164		return 0;
165
166	/* Find next power of 2 >= size. */
167	log2 = sizeof(size) * 8 - __builtin_clzl(size-1);
168
169	/* Compute freelist index, based on log2(size). */
170	index = (log2 - MALLOC_MINSIZE_LOG2 + MALLOC_LOG2_INCREMENT - 1) /
171	        MALLOC_LOG2_INCREMENT;
172
173	return index <= RTE_HEAP_NUM_FREELISTS-1?
174	        index: RTE_HEAP_NUM_FREELISTS-1;
175}
176
177/*
178 * Add the specified element to its heap's free list.
179 */
180void
181malloc_elem_free_list_insert(struct malloc_elem *elem)
182{
183	size_t idx;
184
185	idx = malloc_elem_free_list_index(elem->size - MALLOC_ELEM_HEADER_LEN);
186	elem->state = ELEM_FREE;
187	LIST_INSERT_HEAD(&elem->heap->free_head[idx], elem, free_list);
188}
189
190/*
191 * Remove the specified element from its heap's free list.
192 */
193static void
194elem_free_list_remove(struct malloc_elem *elem)
195{
196	LIST_REMOVE(elem, free_list);
197}
198
199/*
200 * reserve a block of data in an existing malloc_elem. If the malloc_elem
201 * is much larger than the data block requested, we split the element in two.
202 * This function is only called from malloc_heap_alloc so parameter checking
203 * is not done here, as it's done there previously.
204 */
205struct malloc_elem *
206malloc_elem_alloc(struct malloc_elem *elem, size_t size, unsigned align,
207		size_t bound)
208{
209	struct malloc_elem *new_elem = elem_start_pt(elem, size, align, bound);
210	const size_t old_elem_size = (uintptr_t)new_elem - (uintptr_t)elem;
211	const size_t trailer_size = elem->size - old_elem_size - size -
212		MALLOC_ELEM_OVERHEAD;
213
214	elem_free_list_remove(elem);
215
216	if (trailer_size > MALLOC_ELEM_OVERHEAD + MIN_DATA_SIZE) {
217		/* split it, too much free space after elem */
218		struct malloc_elem *new_free_elem =
219				RTE_PTR_ADD(new_elem, size + MALLOC_ELEM_OVERHEAD);
220
221		split_elem(elem, new_free_elem);
222		malloc_elem_free_list_insert(new_free_elem);
223	}
224
225	if (old_elem_size < MALLOC_ELEM_OVERHEAD + MIN_DATA_SIZE) {
226		/* don't split it, pad the element instead */
227		elem->state = ELEM_BUSY;
228		elem->pad = old_elem_size;
229
230		/* put a dummy header in padding, to point to real element header */
231		if (elem->pad > 0){ /* pad will be at least 64-bytes, as everything
232		                     * is cache-line aligned */
233			new_elem->pad = elem->pad;
234			new_elem->state = ELEM_PAD;
235			new_elem->size = elem->size - elem->pad;
236			set_header(new_elem);
237		}
238
239		return new_elem;
240	}
241
242	/* we are going to split the element in two. The original element
243	 * remains free, and the new element is the one allocated.
244	 * Re-insert original element, in case its new size makes it
245	 * belong on a different list.
246	 */
247	split_elem(elem, new_elem);
248	new_elem->state = ELEM_BUSY;
249	malloc_elem_free_list_insert(elem);
250
251	return new_elem;
252}
253
254/*
255 * joing two struct malloc_elem together. elem1 and elem2 must
256 * be contiguous in memory.
257 */
258static inline void
259join_elem(struct malloc_elem *elem1, struct malloc_elem *elem2)
260{
261	struct malloc_elem *next = RTE_PTR_ADD(elem2, elem2->size);
262	elem1->size += elem2->size;
263	next->prev = elem1;
264}
265
266/*
267 * free a malloc_elem block by adding it to the free list. If the
268 * blocks either immediately before or immediately after newly freed block
269 * are also free, the blocks are merged together.
270 */
271int
272malloc_elem_free(struct malloc_elem *elem)
273{
274	if (!malloc_elem_cookies_ok(elem) || elem->state != ELEM_BUSY)
275		return -1;
276
277	rte_spinlock_lock(&(elem->heap->lock));
278	size_t sz = elem->size - sizeof(*elem);
279	uint8_t *ptr = (uint8_t *)&elem[1];
280	struct malloc_elem *next = RTE_PTR_ADD(elem, elem->size);
281	if (next->state == ELEM_FREE){
282		/* remove from free list, join to this one */
283		elem_free_list_remove(next);
284		join_elem(elem, next);
285		sz += sizeof(*elem);
286	}
287
288	/* check if previous element is free, if so join with it and return,
289	 * need to re-insert in free list, as that element's size is changing
290	 */
291	if (elem->prev != NULL && elem->prev->state == ELEM_FREE) {
292		elem_free_list_remove(elem->prev);
293		join_elem(elem->prev, elem);
294		sz += sizeof(*elem);
295		ptr -= sizeof(*elem);
296		elem = elem->prev;
297	}
298	malloc_elem_free_list_insert(elem);
299
300	/* decrease heap's count of allocated elements */
301	elem->heap->alloc_count--;
302
303	memset(ptr, 0, sz);
304
305	rte_spinlock_unlock(&(elem->heap->lock));
306
307	return 0;
308}
309
310/*
311 * attempt to resize a malloc_elem by expanding into any free space
312 * immediately after it in memory.
313 */
314int
315malloc_elem_resize(struct malloc_elem *elem, size_t size)
316{
317	const size_t new_size = size + MALLOC_ELEM_OVERHEAD;
318	/* if we request a smaller size, then always return ok */
319	const size_t current_size = elem->size - elem->pad;
320	if (current_size >= new_size)
321		return 0;
322
323	struct malloc_elem *next = RTE_PTR_ADD(elem, elem->size);
324	rte_spinlock_lock(&elem->heap->lock);
325	if (next ->state != ELEM_FREE)
326		goto err_return;
327	if (current_size + next->size < new_size)
328		goto err_return;
329
330	/* we now know the element fits, so remove from free list,
331	 * join the two
332	 */
333	elem_free_list_remove(next);
334	join_elem(elem, next);
335
336	if (elem->size - new_size >= MIN_DATA_SIZE + MALLOC_ELEM_OVERHEAD){
337		/* now we have a big block together. Lets cut it down a bit, by splitting */
338		struct malloc_elem *split_pt = RTE_PTR_ADD(elem, new_size);
339		split_pt = RTE_PTR_ALIGN_CEIL(split_pt, RTE_CACHE_LINE_SIZE);
340		split_elem(elem, split_pt);
341		malloc_elem_free_list_insert(split_pt);
342	}
343	rte_spinlock_unlock(&elem->heap->lock);
344	return 0;
345
346err_return:
347	rte_spinlock_unlock(&elem->heap->lock);
348	return -1;
349}
350