Models whose request geometry opts out of the generic dummy run (H3: t2va
needs an explicit aspect ratio and a bounded duration) can declare a
dlo_dummy_run_recipe. Under distributed layerwise offload the engine's
startup warmup runs it, so the learned cache-retention budget is primed
before real traffic instead of on the first request.
H3 declares a maximum-duration t2va generation: duration is the only
workload variable at the fixed 768 short edge, so the learned peak
dominates every production request and no real request re-learns. Validated
on L20X: all cold-start releases happen during the startup warmup, zero
during requests; first request 15.91 s vs 16.7 s unwarmed, steady 14.9 s;
startup gains one max-length generation (~10-20 s). Non-DLO deployments
keep the opted-out generic warmup unchanged.
Signed-off-by: hsliuustc0106 <liuhongsheng4@huawei.com>