Ingo, Is there any chance that the softirq preemption feature from the -rt kernel can be pushed upstream? Currently I am testing 2.6.14-rt21 with PREEMPT_DESKTOP and hard/softirq preemption disabled in order to simulate the behavior of 2.6.14 mainline. The network TX softirq is the longest non-preemptible code path, it can run for 5-6ms. However I can see that the preempt_count drops to zero on many occasions, which IIRC means that no locks are held and we could easily preempt at that point. Without softirq preemption I don't see how we have any chance of meeting the 1ms goal for desktop responsiveness that was decided on at OLS 2004. Lee