Ling3-Tiny-UBTree-B16
Website · Paper · Target model
Ling3-Tiny-UBTree-B16 is a UBTree speculative-decoding draft model for
inclusionAI/Ling-3.0-tiny. It combines a
five-layer DFlash backbone with a learned bigram selector to propose multiple
candidate continuations for target-model verification.
This checkpoint is used alongside the matching target model; it cannot serve
as a standalone text-generation model.
How UBTree works
[Image blocked: UBTree architecture and tree-native training pipeline]
UBTree pipeline
UBTree pairs a unigram proposer with a bigram selector:
- A DFlash backbone proposes candidate tokens for future positions in parallel.
- The selector scores transitions between adjacent candidates in parallel.
- Tree construction retains promising branches within a verification budget.
- The target verifies the tree and commits the accepted continuation.
The paper also introduces tree-native training with renormalized KL supervision
on high-temperature target traces, encouraging plausible alternative branches.
See the paper for the method and experiments.
Model specifications
The parameter count covers tensors distributed in this repository. The draft
shares token embeddings and the language-model head with the target; these
shared weights are not included here. B16 denotes the draft block size, not
the verification tree's node budget.
Serving with SGLang
Use the asahi/ubtree SGLang branch for the commands below.
Upstream integration is in progress in sgl-project/sglang#44050.
Benchmark results
All methods use block size 16, TP1, concurrency 1, BF16, and greedy
no-thinking decoding. UBTree uses a 49-node tree.
Each cell shows acceptance length / E2E speedup / TPS (tok/s).
E2E speedup is relative to target-only autoregressive (AR) decoding.
TPS is total returned output tokens divided by total client HTTP time,
including prefill and generation. Acceptance length is returned output tokens
divided by target verification calls, including the anchor. Speculative AL and
TPS are independent medians over three runs; E2E speedup is speculative TPS
divided by the matched AR TPS. AR uses one run per benchmark.
Each Avg. value is the arithmetic mean of the six per-dataset values,
computed before display rounding. Average speedup is the mean of per-dataset
speedups, rather than the ratio of average TPS.
Citation
If you use UBTree in your work, please cite:
License
The model weights are released under the MIT License. The pipeline figure
is from Liang et al., Figure 2,
reproduced without modification under CC BY 4.0.