Libra: Efficient Resource Management for Agentic RL Post-Training
On the map: LLM agents and tool use → Reinforcement learning for LLM agents
Abstract (arXiv)
Reinforcement learning (RL) has emerged as a standard post-training paradigm for shaping large language models (LLMs) into capable agents. In agentic RL, the rollout stage generates trajectories while invoking tools, producing long-tailed and non-stationary workloads that expose two fundamental challenges. First, due to the long-tailed response distribution, a small fraction of trajectories dominates rollout makespan.Second, rollout and training differ in their compute patterns, memory demands, and sensitivity to sequence length. As the policy evolves, shifts in the workload distribution further change their relative resource demands, making it difficult to maintain balanced execution across the two stages. We present Libra, an adaptive runtime for agentic RL post-training with two complementary components: (1) intra-stage scheduling via a Causality-Guided Bucket Scheduler that routes requests across execution buckets with different parallelism configurations, reducing delays from rollout stragglers; and (2) cross-stage coordination that dynamically reallocates workers between rollout and training as the workload changes. It moves workers between the two stages through a non-blocking protocol without interrupting ongoing training. Evaluated on a 48x NVIDIA A800 GPU cluster and a 160x Ascend 910B3 NPU cluster across three agentic benchmarks, Libra achieves up to 4.2x higher throughput and up to 2.7x faster reward convergence
Key facts. Cited by 2 papers in the map (data through 7 Oct 2026). Placed in Reinforcement learning for LLM agents, one of 16 directions in LLM agents and tool use. Builds on 49 of its 67 references that are in the map. First posted on arXiv 2 Jun 2026.
Builds on
49 of 67 references.
Closest ancestors · 7
Same direction, newest first
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- 2025VerlTool: Towards Holistic Agentic Reinforcement Learning with Tool Use1 Sep
- 2025ReTool: Reinforcement Learning for Strategic Tool Use in LLMs15 Apr
- 2023Reflexion: Language Agents with Verbal Reinforcement Learning20 Mar
Other references · 42
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