On Mon, 9 Sep 2013 15:08:53 +0200 Frederic Weisbecker <fweis...@gmail.com> wrote:
> On Mon, Sep 09, 2013 at 08:55:04AM -0400, Steven Rostedt wrote: > > From reading the context a bit more, it seems that the per cpu value is > > more a "per task" value that happens to be using per cpu variables, and > > changes on context switches. Is that correct? > > Yeah that's probably what confuse so many people. It's indeed at the same > time a task state and a per cpu state. Especially since the function name itself is "rcu_is_cpu_idle()" which tells you it's a cpu state, and not a task state. Why would you care in RCU if CPU 1 is idle if you are on CPU 2? The name should be changed. > > Pretty much like tsk->ti->preempt_count that people now try to implement > through a per cpu value. Actually, preempt_count is more a CPU state than a task state. When preempt_count is set, that CPU can not schedule out the current task. It really has nothing to do with the task itself. It's the CPU that can't do something. Preempt count should never traverse with a task from one CPU to another. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
