Hi Leo.... On Wed, Oct 14, 2009 at 5:34 PM, Leonidas . <leonidas137@xxxxxxxxx> wrote: > Hi, > > I am running Ubuntu Jaunty currently, with kernel version 2.6.28 kernel. > I was assuming that, all the kernels above 2.6 will have CONFIG_PREEMPT > =1 by default, but my default kernel does not have it set. > > Is that the norm? I can understand certain use cases which might require > the kernel to be non pre-emptible but even a regular desktop distro does > not have it set? Surprising? IMO, not enabling full preemption but instead using voluntary preemption is like picking middle path. Full preemption will force CPU to do rescheduling (eventually there will be context switch) whenever higher priority task are ready to run. It will reduce throughput but theoritically giving you lower latency Using no preemption at all, as you can imagine, is better suited for server jobs or CPU bounded jobs, as there is unlikely need to switch between tasks too often. So between these two extreme preemption model, voluntary one is picked. Of course, if might be not for everyone... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
