[Feature] AIBrix KVCache common

.github/workflows/python-aibrix-kvcache-tests.yml

@@ -0,0 +1,45 @@
+name: Python AIBrix KVCache Tests
+
+on:
+  push:
+    branches: [ "main", "release-*" ]
+    paths:
+      - 'python/aibrix_kvcache/**'
+  pull_request:
+    branches: [ "main" ]
+    paths:
+      - 'python/aibrix_kvcache/**'
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.10", "3.11", "3.12"]
+    name: Lint
+    steps:
+      - name: Check out source repository
+        uses: actions/checkout@v4
+      - name: Set up Python environment ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          cd python/aibrix_kvcache
+          python -m pip install --upgrade pip
+          pip install -U pip poetry
+          poetry config virtualenvs.create false
+          poetry install --no-root --with dev
+      - name: Run Ruff
+        run: |
+          cd python/aibrix_kvcache
+          python -m ruff check .
+          python -m ruff format --check .
+      - name: Run mypy
+        run: |
+          cd python/aibrix_kvcache
+          python -m mypy .
+      - name: Run Test
+        run: |
+          cd python/aibrix_kvcache/tests
+          python -m pytest .

.github/workflows/python-tests.yml → .github/workflows/python-aibrix-tests.yml

@@ -1,14 +1,14 @@
-name: Python Tests
+name: Python AIBrix Tests
 
 on:
   push:
     branches: [ "main", "release-*" ]
     paths:
-      - 'python/**'
+      - 'python/aibrix/**'
   pull_request:
     branches: [ "main" ]
     paths:
-      - 'python/**'
+      - 'python/aibrix/**'
 jobs:
   lint:
     runs-on: ubuntu-latest

python/aibrix_kvcache/.gitignore

@@ -0,0 +1,12 @@
+# python
+__pycache__
+
+# pytest
+.benchmarks
+.pytest_cache
+
+# ruff
+.ruff_cache
+
+# mypy
+.mypy_cache

python/aibrix_kvcache/LICENSE

@@ -0,0 +1,201 @@
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python/aibrix_kvcache/README.md

@@ -0,0 +1,45 @@
+# AIBrix KV Cache Offloading Framework for Cross-Engine KV Reuse
+AIBrix KV cache offloading framework provides several common functionalities for cross-engine KV reuse use cases:
+
+**Tensor Parallelism Aware Management**: When inference engine (e.g., vLLM) uses tensor parallelism, each participating engine instance fetches KV tensors independently from the cache backend. In case of cache misses, before proceeding with prefill computation, participants must align the potentially different number of KV tensors fetched from the external KV cache service to ensure a consistent view .
+
+**Embedded Cache w/ CPU Memory**: To meet performance requirements, it's common to have a small CPU memory-based cache embedded in the engine to avoid frequently accessing remote cache backends.
+
+**Selective KV Cache Offloading**: Enables fine-grained control over offloading strategies and thus is crucial in optimizing performance across diverse deployment environments:
+1. Many cloud providers and companies deploy lower-end GPU instances without high-speed interconnects like RDMA, suited for tasks related to 7B/8B models running on 24/32GiB GPU cards. In these setups, GPUs within the same instance (typically 8-16 GPUs) share a single VPC NIC, leading to significant network bandwidth contention. Selective KV cache offloading (e.g., only offloading KV tensors identified by the employed eviction policy as hot rather than offloading all KV tensors) helps mitigate this issue by reducing unnecessary data transfers and conserving limited network bandwidth.
+2. Even in high-performance environments with RDMA-equipped GPUs, selective KV cache offloading can enhance efficiency by limiting the PCIe bandwidth consumed by remote data movement. While RDMA enables low-latency, high-bandwidth communication, remote data access still incurs higher latency than local memory access. By leveraging selective KV offloading, the framework reduces the frequency of remote data transfers, preserving PCIe bandwidth and ensuring that local memory access remains the preferred data pathway.
+To achieve selective KV cache offloading, we introduce an eviction policy layer that can be extended and customized with advanced offloading strategies to determine which KV tensors should be offloaded. Within this layer, multiple callbacks are available to support different offloading modes, including offloading all KV tensors, only hot KV tensors, or only cold KV tensors, with the definition of "hot" and "cold" being determined by the specific eviction policy in use. In this initial PR, the framework will provide built-in support for LRU, FIFO, and S3FIFO eviction policies.
+
+## Quick Start
+### Installation
+AIBrix KV cache offloading framework can be installed by `pip`.
+
+```sh
+pip install aibrix-kvcache
+```
+
+## Contributing
+We welcome contributions from the community! Check out our [contributing guidelines](https://github.com/vllm-project/aibrix/blob/main/CONTRIBUTING.md) to see how you can make a difference.
+
+### Build from source
+
+```bash
+# This may take several minutes
+pip install -e .
+```
+
+### Lint, Format and Type Check
+
+Before contribute your code, please run the following commands to ensure that your code passes the tests and linting checks.
+
+```bash
+# install dependencies
+poetry install --no-root --with dev
+
+# linting, formatting and type checking
+bash ./scripts/format.sh
+```
+
+## License
+
+AI Runtime is licensed under the [APACHE License](https://github.com/vllm-project/aibrix/LICENSE.md).

python/aibrix_kvcache/aibrix_kvcache/cache_handle.py

@@ -0,0 +1,69 @@
+# Copyright 2024 The Aibrix Team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# 	http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from abc import ABC, abstractmethod
+from typing import Sequence, Tuple
+
+import torch
+
+from .memory import MemoryRegion
+
+
+class KVCacheHandle(ABC):
+    """Cache handle to support zero-copy APIs."""
+
+    @property
+    @abstractmethod
+    def memory_regions(self) -> Sequence[MemoryRegion]:
+        raise NotImplementedError
+
+    @abstractmethod
+    def to_tensors(self) -> Sequence[torch.Tensor]:
+        raise NotImplementedError
+
+    @abstractmethod
+    def release(self) -> None:
+        raise NotImplementedError
+
+    @abstractmethod
+    def __len__(self) -> int:
+        raise NotImplementedError
+
+
+class MemoryRegionKVCacheHandle(KVCacheHandle):
+    def __init__(
+        self,
+        block_dtype: torch.dtype,
+        block_shape: Tuple[int, ...],
+        mrs: Sequence[MemoryRegion],
+    ) -> None:
+        self._block_dtype = block_dtype
+        self._block_shape = block_shape
+        self._mrs = mrs
+
+    @property
+    def memory_regions(self) -> Sequence[MemoryRegion]:
+        return self._mrs
+
+    def to_tensors(self) -> Sequence[torch.Tensor]:
+        return MemoryRegion.to_tensors(
+            self._mrs, self._block_dtype, self._block_shape
+        )
+
+    def release(self) -> None:
+        for mr in self._mrs:
+            mr.ref_down()
+
+    def __len__(self) -> int:
+        return len(self._mrs)