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af814ff9a8
This was inspired by Hoard: A Scalable Memory Allocator for Multithreaded Applications Emery D. Berger, Kathryn S. McKinley, Robert D. Blumofe, Paul R. Wilson, It's not anywhere near the same implementation, but it did take a few basic concepts. The idea is twofold: 1) A pool of memory from which blocks can be allocated and then freed en-mass and is fairly efficient for small (4-16 byte) blocks 2) Tread safety for use with the Vulkan renderer (and any other multi-threaded tasks). However, based on the Hoard paper, small allocations are cache-line aligned. On top of that, larger allocations are page aligned. I suspect it would help qfvis somewhat if I ever get around to tweaking qfvis to use cmem.
96 lines
2.7 KiB
C
96 lines
2.7 KiB
C
/*
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cmem.h
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Cache-line aligned memory allocator
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Copyright (C) 2020 Bill Currie <bill@taniwha.org>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to:
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Free Software Foundation, Inc.
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59 Temple Place - Suite 330
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Boston, MA 02111-1307, USA
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*/
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#ifndef __cmem_h
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#define __cmem_h
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#include "QF/qtypes.h"
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#define MEM_LINE_SIZE 64
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typedef struct memline_s {
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struct memline_s *next;
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size_t size;
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size_t pad[6];
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} memline_t;
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typedef struct memsline_s {
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struct memsline_s *next;
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size_t size:2;
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size_t list:4;
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size_t prev:58; // memsline_t **
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} memsline_t;
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typedef struct memblock_s {
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struct memblock_s *next;
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struct memblock_s **prev;
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/* The pointer to pass to free()
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*/
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void *mem;
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memline_t *free_lines;
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/* Size of memory region before block "header".
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*
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* Since large blocks are allocated with page-size alignment, odds are
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* high that the there will be many cache lines "wasted" in the space
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* between the address returned from aligned_alloc (to cache-line
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* alignment) and the block itself. Setting them up as a pool makes the
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* lines available for smaller allocations, thus reducing waste.
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*/
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size_t pre_size;
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/* Size of memory region after block "header".
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*
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* Will be 0 for blocks that were allocated exclusively for small
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* allocations, otherwise indicates the size of the allocated block.
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*/
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size_t post_size;
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/* True if the post-header block is free to be reused.
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*/
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int post_free;
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int pad;
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size_t pre_allocated;
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} memblock_t;
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typedef struct memsuper_s {
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size_t page_size;
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size_t page_mask;
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memblock_t *memblocks;
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/* Allocated cache lines from which smaller blocks can be allocated.
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*
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* The index is the base-2 log minus 2 of the size of the elements in the
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* cache line from which an element was last freed. Only 4-32 bytes are of
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* interest because nothing smaller than 4 bytes (int/float) will be
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* allocated, and 64 bytes and up consume entire cache lines.
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*/
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memsline_t *last_freed[4];
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size_t pad;
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} memsuper_t;
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memsuper_t *new_memsuper (void);
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void delete_memsuper (memsuper_t *super);
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void *cmemalloc (memsuper_t *super, size_t size);
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void cmemfree (memsuper_t *super, void *mem);
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#endif//__cmem_h
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