On 12/22/21 06:41, Sebastian Andrzej Siewior wrote:
Based on my understanding the optimisation with task_obj for in_task() mask sense on non-PREEMPTIBLE kernels because preempt_disable()/enable() is optimized away. This could be then restricted to !CONFIG_PREEMPTION kernel instead to only PREEMPT_RT. With CONFIG_PREEMPT_DYNAMIC a non-PREEMPTIBLE kernel can also be configured but these kernels always have preempt_disable()/enable() present so it probably makes no sense here for the optimisation. Restrict the optimisation to !CONFIG_PREEMPTION kernels. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
If PREEMPT_DYNAMIC is selected, PREEMPTION will also be set. My understanding is that some distros are going to use PREEMPT_DYNAMIC, but default to PREEMPT_VOLUNTARY. So I don't believe it is a good idea to disable the optimization based on PREEMPTION alone.
Regards, Longman
