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[None][fix] Pre-subtract non-first-chunk context costs in reuse budge… #12806

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Merged
liji-nv merged 1 commit into from
Apr 7, 2026
Merged

[None][fix] Pre-subtract non-first-chunk context costs in reuse budge… #12806

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18 changes: 15 additions & 3 deletions tensorrt_llm/_torch/pyexecutor/resource_manager.py
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Original file line number Diff line number Diff line change
Expand Up @@ -630,6 +630,14 @@ def prepare_resources(self, scheduled_batch: ScheduledRequests):
for req in scheduled_batch.generation_requests)
remaining_budget = self.max_num_tokens - gen_tokens

# Pre-subtract the fixed cost of non-first-chunk context
# requests. These have no reuse to re-validate and their
# compute cost is committed, so first-chunk budget checks
# must see the budget with these costs already removed.
for req in scheduled_batch.context_requests:
if not req.is_first_context_chunk:
remaining_budget -= req.context_chunk_size

accepted_ctx_requests = []

# allocate KV Cache
Expand Down Expand Up @@ -688,9 +696,13 @@ def prepare_resources(self, scheduled_batch: ScheduledRequests):
block_ids = self.get_cache_indices(req)
self.kv_connector_manager.update_state_after_alloc(
req, block_ids)
elif remaining_budget is not None:
reusable = (req.estimated_reusable_tokens
if req.is_first_context_chunk else 0)
elif remaining_budget is not None and req.is_first_context_chunk:
# First-chunk request that skipped add_sequence
# (e.g. kv_connector said not to). Subtract its
# estimated cost so later first-chunk checks see a
# correct budget. Non-first-chunk costs were
# already pre-subtracted above.
reusable = req.estimated_reusable_tokens
remaining_budget -= self._estimate_post_reuse_compute(
reusable, req.context_chunk_size, req.prompt_len)

Expand Down
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