Re: [PATCH v8 4/5] locking/qspinlock: Introduce starvation avoidance into CNA

Peter Zijlstra
2020-01-25T11:20:59Z

On Fri, Jan 24, 2020 at 01:51:34PM -0500, Waiman Long wrote:

< 71 lines of garbage >

> > You can use the in_task() macro in include/linux/preempt.h. This is
> > just a percpu preempt_count read and test. If in_task() is false, it
> > is in a {soft|hard}irq or nmi context. If it is true, you can check
> > the rt_task() macro to see if it is an RT task. That will access to
> > the current task structure. So it may cost a little bit more if you
> > want to handle the RT task the same way.
> >
> We may not need to do that for softIRQ context. If that is the case, you
> can use in_irq() which checks for hardirq and nmi only. Peter, what is
> your thought on that?

Can you lot please start trimming emails when you reply?