1 /* SPDX-License-Identifier: BSD-3-Clause
2 * Copyright(c) 2010-2014 Intel Corporation
5 #ifndef __INCLUDE_RTE_BITMAP_H__
6 #define __INCLUDE_RTE_BITMAP_H__
16 * The bitmap component provides a mechanism to manage large arrays of bits
17 * through bit get/set/clear and bit array scan operations.
19 * The bitmap scan operation is optimized for 64-bit CPUs using 64/128 byte cache
20 * lines. The bitmap is hierarchically organized using two arrays (array1 and
21 * array2), with each bit in array1 being associated with a full cache line
22 * (512/1024 bits) of bitmap bits, which are stored in array2: the bit in array1
23 * is set only when there is at least one bit set within its associated array2
24 * bits, otherwise the bit in array1 is cleared. The read and write operations
25 * for array1 and array2 are always done in slabs of 64 bits.
27 * This bitmap is not thread safe. For lock free operation on a specific bitmap
28 * instance, a single writer thread performing bit set/clear operations is
29 * allowed, only the writer thread can do bitmap scan operations, while there
30 * can be several reader threads performing bit get operations in parallel with
31 * the writer thread. When the use of locking primitives is acceptable, the
32 * serialization of the bit set/clear and bitmap scan operations needs to be
33 * enforced by the caller, while the bit get operation does not require locking
39 #include <rte_common.h>
40 #include <rte_config.h>
41 #include <rte_debug.h>
42 #include <rte_memory.h>
43 #include <rte_branch_prediction.h>
44 #include <rte_prefetch.h>
47 #define RTE_BITMAP_SLAB_BIT_SIZE 64
48 #define RTE_BITMAP_SLAB_BIT_SIZE_LOG2 6
49 #define RTE_BITMAP_SLAB_BIT_MASK (RTE_BITMAP_SLAB_BIT_SIZE - 1)
52 #define RTE_BITMAP_CL_BIT_SIZE (RTE_CACHE_LINE_SIZE * 8)
53 #define RTE_BITMAP_CL_BIT_SIZE_LOG2 (RTE_CACHE_LINE_SIZE_LOG2 + 3)
54 #define RTE_BITMAP_CL_BIT_MASK (RTE_BITMAP_CL_BIT_SIZE - 1)
56 #define RTE_BITMAP_CL_SLAB_SIZE (RTE_BITMAP_CL_BIT_SIZE / RTE_BITMAP_SLAB_BIT_SIZE)
57 #define RTE_BITMAP_CL_SLAB_SIZE_LOG2 (RTE_BITMAP_CL_BIT_SIZE_LOG2 - RTE_BITMAP_SLAB_BIT_SIZE_LOG2)
58 #define RTE_BITMAP_CL_SLAB_MASK (RTE_BITMAP_CL_SLAB_SIZE - 1)
60 /** Bitmap data structure */
62 /* Context for array1 and array2 */
63 uint64_t *array1
; /**< Bitmap array1 */
64 uint64_t *array2
; /**< Bitmap array2 */
65 uint32_t array1_size
; /**< Number of 64-bit slabs in array1 that are actually used */
66 uint32_t array2_size
; /**< Number of 64-bit slabs in array2 */
68 /* Context for the "scan next" operation */
69 uint32_t index1
; /**< Bitmap scan: Index of current array1 slab */
70 uint32_t offset1
; /**< Bitmap scan: Offset of current bit within current array1 slab */
71 uint32_t index2
; /**< Bitmap scan: Index of current array2 slab */
72 uint32_t go2
; /**< Bitmap scan: Go/stop condition for current array2 cache line */
74 /* Storage space for array1 and array2 */
79 __rte_bitmap_index1_inc(struct rte_bitmap
*bmp
)
81 bmp
->index1
= (bmp
->index1
+ 1) & (bmp
->array1_size
- 1);
84 static inline uint64_t
85 __rte_bitmap_mask1_get(struct rte_bitmap
*bmp
)
87 return (~1llu) << bmp
->offset1
;
91 __rte_bitmap_index2_set(struct rte_bitmap
*bmp
)
93 bmp
->index2
= (((bmp
->index1
<< RTE_BITMAP_SLAB_BIT_SIZE_LOG2
) + bmp
->offset1
) << RTE_BITMAP_CL_SLAB_SIZE_LOG2
);
96 static inline uint32_t
97 __rte_bitmap_get_memory_footprint(uint32_t n_bits
,
98 uint32_t *array1_byte_offset
, uint32_t *array1_slabs
,
99 uint32_t *array2_byte_offset
, uint32_t *array2_slabs
)
101 uint32_t n_slabs_context
, n_slabs_array1
, n_cache_lines_context_and_array1
;
102 uint32_t n_cache_lines_array2
;
103 uint32_t n_bytes_total
;
105 n_cache_lines_array2
= (n_bits
+ RTE_BITMAP_CL_BIT_SIZE
- 1) / RTE_BITMAP_CL_BIT_SIZE
;
106 n_slabs_array1
= (n_cache_lines_array2
+ RTE_BITMAP_SLAB_BIT_SIZE
- 1) / RTE_BITMAP_SLAB_BIT_SIZE
;
107 n_slabs_array1
= rte_align32pow2(n_slabs_array1
);
108 n_slabs_context
= (sizeof(struct rte_bitmap
) + (RTE_BITMAP_SLAB_BIT_SIZE
/ 8) - 1) / (RTE_BITMAP_SLAB_BIT_SIZE
/ 8);
109 n_cache_lines_context_and_array1
= (n_slabs_context
+ n_slabs_array1
+ RTE_BITMAP_CL_SLAB_SIZE
- 1) / RTE_BITMAP_CL_SLAB_SIZE
;
110 n_bytes_total
= (n_cache_lines_context_and_array1
+ n_cache_lines_array2
) * RTE_CACHE_LINE_SIZE
;
112 if (array1_byte_offset
) {
113 *array1_byte_offset
= n_slabs_context
* (RTE_BITMAP_SLAB_BIT_SIZE
/ 8);
116 *array1_slabs
= n_slabs_array1
;
118 if (array2_byte_offset
) {
119 *array2_byte_offset
= n_cache_lines_context_and_array1
* RTE_CACHE_LINE_SIZE
;
122 *array2_slabs
= n_cache_lines_array2
* RTE_BITMAP_CL_SLAB_SIZE
;
125 return n_bytes_total
;
129 __rte_bitmap_scan_init(struct rte_bitmap
*bmp
)
131 bmp
->index1
= bmp
->array1_size
- 1;
132 bmp
->offset1
= RTE_BITMAP_SLAB_BIT_SIZE
- 1;
133 __rte_bitmap_index2_set(bmp
);
134 bmp
->index2
+= RTE_BITMAP_CL_SLAB_SIZE
;
140 * Bitmap memory footprint calculation
143 * Number of bits in the bitmap
145 * Bitmap memory footprint measured in bytes on success, 0 on error
147 static inline uint32_t
148 rte_bitmap_get_memory_footprint(uint32_t n_bits
) {
149 /* Check input arguments */
154 return __rte_bitmap_get_memory_footprint(n_bits
, NULL
, NULL
, NULL
, NULL
);
158 * Bitmap initialization
161 * Number of pre-allocated bits in array2.
163 * Base address of array1 and array2.
165 * Minimum expected size of bitmap.
167 * Handle to bitmap instance.
169 static inline struct rte_bitmap
*
170 rte_bitmap_init(uint32_t n_bits
, uint8_t *mem
, uint32_t mem_size
)
172 struct rte_bitmap
*bmp
;
173 uint32_t array1_byte_offset
, array1_slabs
, array2_byte_offset
, array2_slabs
;
176 /* Check input arguments */
181 if ((mem
== NULL
) || (((uintptr_t) mem
) & RTE_CACHE_LINE_MASK
)) {
185 size
= __rte_bitmap_get_memory_footprint(n_bits
,
186 &array1_byte_offset
, &array1_slabs
,
187 &array2_byte_offset
, &array2_slabs
);
188 if (size
< mem_size
) {
193 memset(mem
, 0, size
);
194 bmp
= (struct rte_bitmap
*) mem
;
196 bmp
->array1
= (uint64_t *) &mem
[array1_byte_offset
];
197 bmp
->array1_size
= array1_slabs
;
198 bmp
->array2
= (uint64_t *) &mem
[array2_byte_offset
];
199 bmp
->array2_size
= array2_slabs
;
201 __rte_bitmap_scan_init(bmp
);
210 * Handle to bitmap instance
212 * 0 upon success, error code otherwise
215 rte_bitmap_free(struct rte_bitmap
*bmp
)
217 /* Check input arguments */
229 * Handle to bitmap instance
232 rte_bitmap_reset(struct rte_bitmap
*bmp
)
234 memset(bmp
->array1
, 0, bmp
->array1_size
* sizeof(uint64_t));
235 memset(bmp
->array2
, 0, bmp
->array2_size
* sizeof(uint64_t));
236 __rte_bitmap_scan_init(bmp
);
240 * Bitmap location prefetch into CPU L1 cache
243 * Handle to bitmap instance
247 * 0 upon success, error code otherwise
250 rte_bitmap_prefetch0(struct rte_bitmap
*bmp
, uint32_t pos
)
255 index2
= pos
>> RTE_BITMAP_SLAB_BIT_SIZE_LOG2
;
256 slab2
= bmp
->array2
+ index2
;
257 rte_prefetch0((void *) slab2
);
264 * Handle to bitmap instance
268 * 0 when bit is cleared, non-zero when bit is set
270 static inline uint64_t
271 rte_bitmap_get(struct rte_bitmap
*bmp
, uint32_t pos
)
274 uint32_t index2
, offset2
;
276 index2
= pos
>> RTE_BITMAP_SLAB_BIT_SIZE_LOG2
;
277 offset2
= pos
& RTE_BITMAP_SLAB_BIT_MASK
;
278 slab2
= bmp
->array2
+ index2
;
279 return (*slab2
) & (1llu << offset2
);
286 * Handle to bitmap instance
291 rte_bitmap_set(struct rte_bitmap
*bmp
, uint32_t pos
)
293 uint64_t *slab1
, *slab2
;
294 uint32_t index1
, index2
, offset1
, offset2
;
296 /* Set bit in array2 slab and set bit in array1 slab */
297 index2
= pos
>> RTE_BITMAP_SLAB_BIT_SIZE_LOG2
;
298 offset2
= pos
& RTE_BITMAP_SLAB_BIT_MASK
;
299 index1
= pos
>> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2
+ RTE_BITMAP_CL_BIT_SIZE_LOG2
);
300 offset1
= (pos
>> RTE_BITMAP_CL_BIT_SIZE_LOG2
) & RTE_BITMAP_SLAB_BIT_MASK
;
301 slab2
= bmp
->array2
+ index2
;
302 slab1
= bmp
->array1
+ index1
;
304 *slab2
|= 1llu << offset2
;
305 *slab1
|= 1llu << offset1
;
312 * Handle to bitmap instance
314 * Bit position identifying the array2 slab
316 * Value to be assigned to the 64-bit slab in array2
319 rte_bitmap_set_slab(struct rte_bitmap
*bmp
, uint32_t pos
, uint64_t slab
)
321 uint64_t *slab1
, *slab2
;
322 uint32_t index1
, index2
, offset1
;
324 /* Set bits in array2 slab and set bit in array1 slab */
325 index2
= pos
>> RTE_BITMAP_SLAB_BIT_SIZE_LOG2
;
326 index1
= pos
>> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2
+ RTE_BITMAP_CL_BIT_SIZE_LOG2
);
327 offset1
= (pos
>> RTE_BITMAP_CL_BIT_SIZE_LOG2
) & RTE_BITMAP_SLAB_BIT_MASK
;
328 slab2
= bmp
->array2
+ index2
;
329 slab1
= bmp
->array1
+ index1
;
332 *slab1
|= 1llu << offset1
;
335 static inline uint64_t
336 __rte_bitmap_line_not_empty(uint64_t *slab2
)
338 uint64_t v1
, v2
, v3
, v4
;
340 v1
= slab2
[0] | slab2
[1];
341 v2
= slab2
[2] | slab2
[3];
342 v3
= slab2
[4] | slab2
[5];
343 v4
= slab2
[6] | slab2
[7];
354 * Handle to bitmap instance
359 rte_bitmap_clear(struct rte_bitmap
*bmp
, uint32_t pos
)
361 uint64_t *slab1
, *slab2
;
362 uint32_t index1
, index2
, offset1
, offset2
;
364 /* Clear bit in array2 slab */
365 index2
= pos
>> RTE_BITMAP_SLAB_BIT_SIZE_LOG2
;
366 offset2
= pos
& RTE_BITMAP_SLAB_BIT_MASK
;
367 slab2
= bmp
->array2
+ index2
;
369 /* Return if array2 slab is not all-zeros */
370 *slab2
&= ~(1llu << offset2
);
375 /* Check the entire cache line of array2 for all-zeros */
376 index2
&= ~ RTE_BITMAP_CL_SLAB_MASK
;
377 slab2
= bmp
->array2
+ index2
;
378 if (__rte_bitmap_line_not_empty(slab2
)) {
382 /* The array2 cache line is all-zeros, so clear bit in array1 slab */
383 index1
= pos
>> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2
+ RTE_BITMAP_CL_BIT_SIZE_LOG2
);
384 offset1
= (pos
>> RTE_BITMAP_CL_BIT_SIZE_LOG2
) & RTE_BITMAP_SLAB_BIT_MASK
;
385 slab1
= bmp
->array1
+ index1
;
386 *slab1
&= ~(1llu << offset1
);
392 __rte_bitmap_scan_search(struct rte_bitmap
*bmp
)
397 /* Check current array1 slab */
398 value1
= bmp
->array1
[bmp
->index1
];
399 value1
&= __rte_bitmap_mask1_get(bmp
);
401 if (rte_bsf64_safe(value1
, &bmp
->offset1
))
404 __rte_bitmap_index1_inc(bmp
);
407 /* Look for another array1 slab */
408 for (i
= 0; i
< bmp
->array1_size
; i
++, __rte_bitmap_index1_inc(bmp
)) {
409 value1
= bmp
->array1
[bmp
->index1
];
411 if (rte_bsf64_safe(value1
, &bmp
->offset1
))
419 __rte_bitmap_scan_read_init(struct rte_bitmap
*bmp
)
421 __rte_bitmap_index2_set(bmp
);
423 rte_prefetch1((void *)(bmp
->array2
+ bmp
->index2
+ 8));
427 __rte_bitmap_scan_read(struct rte_bitmap
*bmp
, uint32_t *pos
, uint64_t *slab
)
431 slab2
= bmp
->array2
+ bmp
->index2
;
432 for ( ; bmp
->go2
; bmp
->index2
++, slab2
++, bmp
->go2
= bmp
->index2
& RTE_BITMAP_CL_SLAB_MASK
) {
434 *pos
= bmp
->index2
<< RTE_BITMAP_SLAB_BIT_SIZE_LOG2
;
439 bmp
->go2
= bmp
->index2
& RTE_BITMAP_CL_SLAB_MASK
;
448 * Bitmap scan (with automatic wrap-around)
451 * Handle to bitmap instance
453 * When function call returns 1, pos contains the position of the next set
454 * bit, otherwise not modified
456 * When function call returns 1, slab contains the value of the entire 64-bit
457 * slab where the bit indicated by pos is located. Slabs are always 64-bit
458 * aligned, so the position of the first bit of the slab (this bit is not
459 * necessarily set) is pos / 64. Once a slab has been returned by the bitmap
460 * scan operation, the internal pointers of the bitmap are updated to point
461 * after this slab, so the same slab will not be returned again if it
462 * contains more than one bit which is set. When function call returns 0,
463 * slab is not modified.
465 * 0 if there is no bit set in the bitmap, 1 otherwise
468 rte_bitmap_scan(struct rte_bitmap
*bmp
, uint32_t *pos
, uint64_t *slab
)
470 /* Return data from current array2 line if available */
471 if (__rte_bitmap_scan_read(bmp
, pos
, slab
)) {
475 /* Look for non-empty array2 line */
476 if (__rte_bitmap_scan_search(bmp
)) {
477 __rte_bitmap_scan_read_init(bmp
);
478 __rte_bitmap_scan_read(bmp
, pos
, slab
);
490 #endif /* __INCLUDE_RTE_BITMAP_H__ */