On Tue, 2012-07-03 at 22:24 +0800, Parmenides wrote: > Hi, > > It is said that kernel can not be preempted in interrupt context > and when it is in a critical section protected by a spin lock > > 1. For the spinlock case, it is easy to get if preemption is allowed > in critical section, the purpose of protection provided by spinlock > can not be achieved readily. I don't know what you mean here.Please clarify. > > 2. For the interrupt context case, I think when processing interrupt, > kernel can be preempted in principle. But, this really increases the > interrupt processing time which further cause longer response time and > data missing in device. Except that, is there any other reasons? data missing in device.Can you elaborate that? Stack space is pretty limited in ISR context.Does that give you a clue? > > 3. Kernel is responsible for prohibiiting passive process switches, > namely preemption, in the above cases. But, It seems that it does not > take care of active process swtiches, namely yield. For example, some > code in a critical section protected by a spinlock can invoke > schedule() to switch process passively. Is this the case? I don't understand this question but we don't switch when we are holding spinlock as that will jeopardize the integrity of the system i.e. suppose you slept while holding spinlock.What would happen? > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@xxxxxxxxxxxxxxxxx > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
