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Diffstat (limited to 'include')
| -rw-r--r-- | include/buddy.h | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/include/buddy.h b/include/buddy.h new file mode 100644 index 0000000..fa97eb0 --- /dev/null +++ b/include/buddy.h @@ -0,0 +1,54 @@ +/* Copyright 2016 IBM Corp. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or + * implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + * Simple power-of-two buddy allocation mechanism. + * + */ +#ifndef __BUDDY_H +#define __BUDDY_H + +#include "bitmap.h" + +#define BUDDY_MAX_ORDER 30 + +struct buddy { + /* max_order is both the height of the tree - 1 and the ^2 of the + * size of the lowest level. + * + * So if we have 512k elements, max_order is 19, which gives us + * a 20 levels tree. + * + * The max supported order is 30 for now. We can increase that + * later if really needed but the performance is going to be + * already pretty bad if we go near that limit. + */ + unsigned int max_order; + + /* For each order, we keep track of how many free modes we + * have there to speed up searches. + */ + unsigned int freecounts[BUDDY_MAX_ORDER + 1]; + bitmap_elem_t map[]; +}; + +extern struct buddy *buddy_create(unsigned int max_order); +extern void buddy_destroy(struct buddy *b); + +extern int buddy_alloc(struct buddy *b, unsigned int order); +extern bool buddy_reserve(struct buddy *b, unsigned int index, unsigned int order); +extern void buddy_free(struct buddy *b, unsigned int index, unsigned int order); +extern void buddy_reset(struct buddy *b); + +#endif /* __BUDDY_H */ |