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by orlp
783 days ago
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> It would require a reverse lookup structure from address to buffer handle, e.g. red-black tree. Maintaining it would no longer be O(1). Well, another solution is enlarging each allocation by 8 bytes and storing the buffer handle in front of the returned allocation. So `free(ptr)` would get the handle as `*((ptr as *const u64) - 1)`. |
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This kind of allocators are usually used for suballocating GPU buffers, so hiding a few bytes of metadata "in-band" can mess up your alignment requirements and not all kinds of GPU memory are even accessible by CPU. Due to false sharing cache problems you would probably want a full cache line (64 bytes) to store the metadata.
For a CPU-only memory allocator your idea could work quite well. It can also be implemented on top of this code without any modifications.