Hi Matt, On Sun, Jun 21, 2015 at 01:42:38PM -0700, Matt Thomas wrote: > > On Jun 21, 2015, at 12:02 PM, Reinoud Zandijk <reinoud%NetBSD.org@localhost> wrote: > > On Sun, Jun 21, 2015 at 08:01:47AM -0700, Matt Thomas wrote: > >> IMO, softints are an abberation and should really be thread priorities > >> and dealt by the thread scheduler. > > > > Each level of softint as a kernel thread that gets woken up by condition > > variables? > > I envision them being hard realtime kernel threads that would preempt lower > priority threads. as in kernel priority threads that get sheduled immediately when they can? without preemption? > > Could in a virtualisation context those threads also be used and be woken > > by signalling the relevant condition variable on reception of say an > > virtio push? > > Could be. > > But my goal is something intrinsically different. In the interrupt, you > signal a condition variable or some other method of making a thread > runnable. A run though the scheduler happens and new thread is selected to > run. > > In addition to exceptions and interrupts using a common trapframe, > cpu_switchto should also need to use a trapframe to store the lwp?s context. > When restoring a trapframe, switchto will need to know which type of > trapframe it was. > > When the interrupt is about to restore the trapframe, if the scheduler > decided to switch to another lwp, it will do so using that lwp?s trapframe. > > The goal is to have near instant context switching without the hackery of > the current preeemption code. This sounds good, esp. if that means we are leaving the concept of `interrupt context' other than the short time before it makes its handling thread runnable. Leaves us with inventarising and porting the drivers to use the new mechanism. Would maybe also be a good idea to clean up our forrest of primitives as so far they are still used. How much time do you recon its going to take to do it properly? Could TNF be tempted to sponser someone, maybe you even ? :) All the best, Reinoud
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