CCCL GridEvenShare principle: each work unit must complete within
bounded time. Python fallback decode was O(seq_len) per step —
at seq_len > 32K, each decode step took seconds, causing HTTP
timeout and service crash during case_truncation (max_tokens=8192).
Raised _PYTORCH_DECODE_THRESHOLD from 32768 to 999999 to force
all decode through ixformer native paged_attention_v1 kernel,
which is O(1) per decode step regardless of sequence length.
Competition submission Job 101 crashed at case_truncation phase
with RemoteDisconnected. Job 66 (competitor) passed this phase
using native kernel at all lengths. Root cause confirmed:
Python fallback too slow for production use.
Also derived from CCCL grid_even_share.cuh DispatchInit:
big_share_items = normal_share_items + tile_items (at most +1 tile)
Never let any block take unbounded work.
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