On 4/27/05, Lars Marowsky-Bree <lmb@xxxxxxx> wrote: > User-space needs to take action and tell us when to stop queuing. Is there any risk of priority inversion? I can't think of a specific issue beyond the userspace daemon process simply not existing that wouldn't hopefully settle out over time and I haven't looked closely at this aspect of 2.6, but it used to be easy to get/keep the cpu busy enough on flushing IO to disk to hurt userspace response times (fibre pulls during heavy buffered, filesystem IO effectively DoSing the machine for a long period). If that sort of thing is still possible, it seems risky relying on a userspace application for timely/meaningful recovery of the resources consumed by the IO.