So how does the information on DPC queue drainage, DPC priorities and DPC targeting affect you as a driver writer? Like I said in the introduction, you may never have a need to call upon the advanced capabilities of DPCs. Only one driver shipped with NT, NDIS, uses DPC targeting and priorities. NDIS uses low importance DPCs that are targeted at a particular processor for its DPC processing.
Many devices require timely response by their interrupt handlers. So what benefit is there to using High-importance DPCs versus the default of Medium? Like most driver-related issues, it really depends on the other drivers that are in the system. However, on average there will be less latency between an ISR and a High-importance DPC than between an ISR and a Low-importance DPC.