Function gqa_pack_ctas 

pub fn gqa_pack_ctas(num_kv_heads: u32, num_seqs: u32) -> u32

2026-09-25: CTAs a packed launch puts on the device: num_kv_heads * num_seqs, a DECODE_GQA_PACK_WIDTH-fold cut from the unpacked num_q_heads * num_seqs. With 4 KV heads on gb10’s 48 SMs the packed grid covers the SMs only from num_seqs = 12.