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Diffstat (limited to 'roms/skiboot/include/buddy.h')
| -rw-r--r-- | roms/skiboot/include/buddy.h | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/roms/skiboot/include/buddy.h b/roms/skiboot/include/buddy.h new file mode 100644 index 000000000..5eaf18d64 --- /dev/null +++ b/roms/skiboot/include/buddy.h @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later +/* + * Simple power-of-two buddy allocation mechanism. + * + * Copyright 2016 IBM Corp. + */ + +#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 */ |