Chunk 17.1

In this chunk, the assistant deployed the new memory-manager binary to a 755 GiB remote machine (RTX 5090, 64 cores) and immediately encountered a runtime panic: “Cannot block the current thread from within a runtime” at engine.rs:913. The root cause was that the evictor callback, called from the async `acquire()` loop, used `blocking_lock()` on a tokio Mutex. The assistant fixed this by replacing `blocking_lock()` with `try_lock()`, allowing the evictor to skip SRS eviction if the mutex is held, and rebuilt/redeployed the binary. Testing then revealed two concurrency bottlenecks. With a tight 100 GiB budget, only one partition synthesized at a time because the 44 GiB SRS + 26 GiB PCE baseline left only ~30 GiB for working sets, and a race in SRS pre‑acquisition caused three concurrent proofs to each reserve 44 GiB simultaneously, further starving the budget. Switching to `total_budget = "auto"` (750 GiB) and `safety_margin = "5GiB"` allowed all 30 partitions to start within one second, but the daemon was then OOM‑killed as RSS hit ~500 GiB while Curio and other processes consumed the remaining memory. The key themes are real‑world deployment and iterative debugging of the budget‑based memory manager; fixing an async‑blocking panic in the evictor; and the critical importance of a properly sized safety margin to account for co‑located processes. The assistant concluded that the budget system works correctly but must be configured with a larger safety margin (e.g., 250 GiB) or an explicit cap to prevent OOM on machines with significant background memory usage.

From Runtime Panic to OOM: The Production Baptism of a GPU Memory Manager 2330 words

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