quakeforge/include/QF/cmem.h

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/*
cmem.h
Cache-line aligned memory allocator
Copyright (C) 2020 Bill Currie <bill@taniwha.org>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to:
Free Software Foundation, Inc.
59 Temple Place - Suite 330
Boston, MA 02111-1307, USA
*/
#ifndef __QF_cmem_h
#define __QF_cmem_h
#include "QF/qtypes.h"
#define MEM_LINE_SIZE 64
#define MAX_CACHE_LINES 9
typedef struct memline_s {
/* chain of free line blocks for fast allocation
* chain begins in memsuper_t
*/
struct memline_s *free_next;
struct memline_s **free_prev;
/* chain of free line blocks within a membock for merging
* chain begins in memblock_t
*/
struct memline_s *block_next;
struct memline_s **block_prev;
size_t size;
/* owning block
*/
struct memblock_s *block;
size_t pad[2];
} memline_t;
typedef struct memsline_s {
struct memsline_s *next;
size_t size:2;
size_t list:4;
size_t prev:58; // memsline_t **
} memsline_t;
typedef struct memblock_s {
struct memblock_s *next;
struct memblock_s **prev;
/* The pointer to pass to free()
*/
void *mem;
memline_t *free_lines;
/* Size of memory region before block "header".
*
* Since large blocks are allocated with page-size alignment, odds are
* high that the there will be many cache lines "wasted" in the space
* between the address returned from aligned_alloc (to cache-line
* alignment) and the block itself. Setting them up as a pool makes the
* lines available for smaller allocations, thus reducing waste.
*/
size_t pre_size;
/* Size of memory region after block "header".
*
* Will be 0 for blocks that were allocated exclusively for small
* allocations, otherwise indicates the size of the allocated block.
*/
size_t post_size;
/* True if the post-header block is free to be reused.
*/
int post_free;
int pad;
size_t pre_allocated;
} memblock_t;
typedef struct memsuper_s {
size_t page_size;
size_t page_mask;
memblock_t *memblocks;
/* Allocated cache lines from which smaller blocks can be allocated.
*
* The index is the base-2 log minus 2 of the size of the elements in the
* cache line from which an element was last freed. Only 4-32 bytes are of
* interest because nothing smaller than 4 bytes (int/float) will be
* allocated, and 64 bytes and up consume entire cache lines.
*/
memsline_t *last_freed[4];
/* Free chache lines grouped by size.
*
* The index is the base-2 log of the MINIMUM number of cache lines
* available in each block. ie, blocks with 4, 5, 6 and 7 lines will all
* be in the third list (index 2). For 4k page sizes, only 6 lists are
* needed (32-63 lines) because a page can hold only 62 lines (1 for the
* control block and one to avoid a cache-line being on a page boundary).
* Having 9 (MAX_CACHE_LINES) lists allows page sizes up to 16kB.
*/
memline_t *free_lines[MAX_CACHE_LINES];
} memsuper_t;
memsuper_t *new_memsuper (void);
void delete_memsuper (memsuper_t *super);
void *cmemalloc (memsuper_t *super, size_t size);
void cmemfree (memsuper_t *super, void *mem);
/** High-tide structure allocator for use in linked lists.
Using a free-list with the name of \c NAME_freelist, return a single
element.
The type of the element must be a structure with a field named \c next.
When the free-list is empty, memory is claimed from the system in blocks.
Elements may be returned to the pool by linking them into the free-list.
\param s The number of structures in the block.
\param t The structure type.
\param n The \c NAME portion of the \c NAME_freelist free-list.
\param super The memsuper_t super block from which to allocate memory.
\hideinitializer
*/
#define CMEMALLOC(s, t, n, super) \
({ \
if (!n##_freelist) { \
int i; \
n##_freelist = cmemalloc ((super), (s) * sizeof (t)); \
for (i = 0; i < (s) - 1; i++) \
n##_freelist[i].next = &n##_freelist[i + 1]; \
n##_freelist[i].next = 0; \
} \
t *v = n##_freelist; \
n##_freelist = n##_freelist->next; \
v; \
})
/** Free a block allocated by #ALLOC
\param n The \c NAME portion of the \c NAME_freelist free-list.
\param p The pointer to the block to be freed.
\hideinitializer
*/
#define CMEMFREE(n, p) \
do { \
p->next = n##_freelist; \
n##_freelist = p; \
} while (0)
#endif//__QF_cmem_h