KVCache simulator for LLM serving cluster routing research

Discrete-event simulator for evaluating KV cache-aware routing policies
in prefill-disaggregated LLM serving clusters. Models a two-tier KV cache
hierarchy (L0 GPU HBM + L1 CPU DRAM) with RDMA/PCIe link contention,
architecture-derived roofline compute (MoE, MLA, DSA), and a cluster-wide
meta-store for prefix-aware routing decisions.

Includes 11 routing policies (random, round_robin, least_loaded,
least_tokens, ttl_aware, precise, min_pd, cache_load, cache_score,
estimated_ttft, prefix_affinity), HuggingFace config.json auto-parsing,
built-in GPU hardware presets (H100/H800/H20/A100/B200), and ablation
tooling for systematic policy comparison across real Alibaba serving traces.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/sim/events.rs

@@ -0,0 +1,15 @@
+//! Event types for the discrete-event engine.
+
+use crate::types::{InstanceId, ReqId};
+
+#[derive(Debug)]
+pub enum Event {
+    /// New trace request arrives at the cluster router.
+    Arrival { req_id: ReqId },
+    /// Per-instance scheduler tick (continuous batching).
+    BatchTick { instance: InstanceId },
+    /// Periodic time-series sample of all instances.
+    Sample,
+    /// Stop the simulation early (used internally).
+    Stop,
+}