The llama.cpp backend ships n_cache_reuse=0 (cross-request KV prefix reuse via
shifting disabled). Enable it by default (256) so repeated prefixes - system
prompts, RAG context, agent scaffolds, multi-turn chat - aren't recomputed. This
is the universally-useful part of 'paged attention' (shared-prefix reuse, which
the upstream maintainers themselves identify as where paged attn actually helps)
and needs none of the block-KV machinery.
Lives in a serving_defaults.go sibling to hardware_defaults.go (device-driven vs
serving-policy defaults); both run from SetDefaults and only fill unset values.
Explicit cache_reuse/n_cache_reuse always wins. Device-independent, so it
propagates to distributed nodes via the model options with no router change.
Shares the backendOptionSet helper with the Phase-1 parallel default.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
94b6cd6355