@@ -256,12 +256,12 @@ speculative decoding, breaking down the guarantees into three key areas:
...
@@ -256,12 +256,12 @@ speculative decoding, breaking down the guarantees into three key areas:
2.**Algorithmic Losslessness**
2.**Algorithmic Losslessness**
\- vLLM’s implementation of speculative decoding is algorithmically validated to be lossless. Key validation tests include:
\- vLLM’s implementation of speculative decoding is algorithmically validated to be lossless. Key validation tests include:
> - **Rejection Sampler Convergence**: Ensures that samples from vLLM’s rejection sampler align with the target
> - **Rejection Sampler Convergence**: Ensures that samples from vLLM’s rejection sampler align with the target
> distribution. [View Test Code](https://github.com/vllm-project/vllm/blob/47b65a550866c7ffbd076ecb74106714838ce7da/tests/samplers/test_rejection_sampler.py#L252)
> distribution. [View Test Code](https://github.com/vllm-project/vllm/blob/47b65a550866c7ffbd076ecb74106714838ce7da/tests/samplers/test_rejection_sampler.py#L252)
> - **Greedy Sampling Equality**: Confirms that greedy sampling with speculative decoding matches greedy sampling
> - **Greedy Sampling Equality**: Confirms that greedy sampling with speculative decoding matches greedy sampling
> without it. This verifies that vLLM's speculative decoding framework, when integrated with the vLLM forward pass and the vLLM rejection sampler,
> without it. This verifies that vLLM's speculative decoding framework, when integrated with the vLLM forward pass and the vLLM rejection sampler,
> provides a lossless guarantee. Almost all of the tests in <gh-dir:tests/spec_decode/e2e>.
> provides a lossless guarantee. Almost all of the tests in <gh-dir:tests/spec_decode/e2e>.
> verify this property using [this assertion implementation](https://github.com/vllm-project/vllm/blob/b67ae00cdbbe1a58ffc8ff170f0c8d79044a684a/tests/spec_decode/e2e/conftest.py#L291)
> verify this property using [this assertion implementation](https://github.com/vllm-project/vllm/blob/b67ae00cdbbe1a58ffc8ff170f0c8d79044a684a/tests/spec_decode/e2e/conftest.py#L291)
3.**vLLM Logprob Stability**
3.**vLLM Logprob Stability**
\- vLLM does not currently guarantee stable token log probabilities (logprobs). This can result in different outputs for the
\- vLLM does not currently guarantee stable token log probabilities (logprobs). This can result in different outputs for the