Update HLSF allocator documentation to reflect v8 behavior

Co-authored-by: Nitload-NSI <105042599+Nitload-NSI@users.noreply.github.com>
This commit is contained in:
copilot-swe-agent[bot]
2026-02-11 01:37:26 +00:00
co-authored by Nitload-NSI
parent 464777da8f
commit 0ec453e62a
@@ -6,7 +6,7 @@ A constant-time (O(1)) allocator for real-time, high-throughput scenarios. It us
- O(1) allocate/free with 10 levels: 64B x 16MB; each level split into 1x/2x/3x segments
- External metadata (`Entry`, `BucketNode`) in dedicated SLABs; user blocks have no headers
- Configurable alignment (>=16B); large block cap per allocation: 32MB
- Configurable alignment (>=16B); maximum block size is configurable at construction time via the `maxBlockSize` parameter (default 32MB, 10 levels). The level array and bucket table are dynamically extended when a larger `maxBlockSize` is specified. There is no implicit fallback to `NativeMemory` for oversized requests.
- Single-threaded implementation (external sync required for multi-threaded use)
## Quick Use
@@ -23,13 +23,13 @@ hlsf.Free(h);
### Alloc(uint size)
- Purpose: Allocate a block of at least `size` bytes.
- Input: `size` in bytes (<= 32MB for internal path; >32MB uses native large allocation).
- Input: `size` in bytes. Must not exceed the `maxBlockSize` configured at construction time (default 32MB). If `size > _maxSize`, an `InvalidOperationException` is thrown.
- Output: `HybridLayerSegregatedFitAllocationHandle` with pointer access and `Span<byte>`.
- Behavior:
- Classify into level/segment and pop a matching bucket; escalate segments and levels if empty.
- Fallback to overflow bucket or carve 32MB from spare memory if all buckets are empty.
- Mark selected `Entry` as Alloc; slice any remainder into `Empty` entries and push to buckets.
- For >32MB requests, use `NativeMemory.AlignedAlloc` and mark `EntryState.Large`.
- There is no implicit fallback to `NativeMemory.AlignedAlloc` for oversized requests — all allocations are served from the pre-allocated arena. The level array and bucket table are dynamically sized based on the `maxBlockSize` parameter.
### Free(HybridLayerSegregatedFitAllocationHandle handle)
@@ -90,7 +90,7 @@ Interpretation: HLSF matches libc allocation throughput under the same workload,
## Detailed Design (summary)
-
- Size classes: levelSizeArray = [64, 256, 1024, 4096, 16384, 65536, 262144, 1048576, 4194304, 16777216] (64B x 4^level)
- Size classes: The default level size array is [64, 256, 1024, 4096, 16384, 65536, 262144, 1048576, 4194304, 16777216] (10 levels, 64B × 4^level). When `maxBlockSize` is specified at construction and exceeds the default range, additional levels are appended (each 4× the previous) to cover the requested maximum block size.
- Segments per level: 1x, 2x, 3x
- Buckets: index = 3 * level + segment (overflow bucket for level > 9)
- Metadata: Entry (external SLAB, position chain), BucketNode (user region, bucket chain)
@@ -143,8 +143,8 @@ Interpretation: HLSF matches libc allocation throughput under the same workload,
### Large Allocations and Spare Memory
- Requests > 32MB use `NativeMemory.AlignedAlloc(size, align)` and mark `State.Large`
- When buckets are empty, `TryAllocateNew32MBBlock` carves a 32MB region from `_spareMemory`, builds an `Empty` entry, and advances the spare pointer
- Requests exceeding the configured `maxBlockSize` are rejected with `InvalidOperationException`. All allocations are served from the pre-allocated arena.
- When all buckets are empty, `TryAllocateNew32MBBlock` carves a region (up to 32MB) from `_spareMemory` to replenish the bucket system, builds an `Empty` entry, and advances the spare pointer
### Alignment