kv-cells: look up the n-gram history in the sequence position index (… - #1
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kv-cells: look up the n-gram history in the sequence position index (…#1feal87 wants to merge 1 commit into
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…28040) get_prev_tokens() rebuilt a (seq, pos) -> token hash map on every ubatch by walking all used cells, while llama_kv_cells already keeps an ordered index of the positions of each sequence in seq_pos, updated on every cell mutation to serve seq_pos_min() and seq_pos_max(). The index now stores (pos, cell) pairs in a std::set instead of a position -> count map, so a repeated position (cache reuse via rm + add, vision inputs with shared positions) yields distinct entries and the removal of a cell erases its own pair. The new seq_pos_tok_le() returns the token of the cell at the largest position <= p in logarithmic time, which is exactly what the old window lookup and its M-RoPE gap fallback computed together. get_prev_tokens() shrinks to a direct lookup per (token, offset) and for_each_token_in() goes away with its only caller. The kv-cache keeps no n-gram logic of its own. Measured on Qwen3.8-Flash-Next UD-Q4_K_XL at 71k context, alternating two binaries with the first run discarded: tg 69.3 -> 72.7 t/s (+4.9%), pp unchanged at ~2720 t/s, greedy output identical, needle retrieved.
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…ggml-org#28040)
get_prev_tokens() rebuilt a (seq, pos) -> token hash map on every ubatch by walking all used cells, while llama_kv_cells already keeps an ordered index of the positions of each sequence in seq_pos, updated on every cell mutation to serve seq_pos_min() and seq_pos_max().
The index now stores (pos, cell) pairs in a std::set instead of a position -> count map, so a repeated position (cache reuse via rm + add, vision inputs with shared positions) yields distinct entries and the removal of a cell erases its own pair. The new seq_pos_tok_le() returns the token of the cell at the largest position <= p in logarithmic time, which is exactly what the old window lookup and its M-RoPE gap fallback computed together.
get_prev_tokens() shrinks to a direct lookup per (token, offset) and for_each_token_in() goes away with its only caller. The kv-cache keeps no n-gram logic of its own.
Measured on Qwen3.8-Flash-Next UD-Q4_K_XL at 71k context, alternating two binaries with the first run discarded: tg 69.3 -> 72.7 t/s (+4.9%), pp unchanged at ~2720 t/s, greedy output identical, needle retrieved.
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