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SubjectRe: [RFC][PATCH v2] sched/rt: Use IPI to trigger RT task push migration instead of pulling
On Wed, Feb 25, 2015 at 12:50:15PM -0500, Steven Rostedt wrote:
> It can't be used for state?
>
> If one CPU writes "zero", and the other CPU wants to decide if the
> system is in the state to do something, isn't a rmb() fine to use?
>
>
> CPU 1:
>
> x = 0;
> /* Tell other CPUs they can now do something */
> smp_wmb();
>
> CPU 2:
> /* Make sure we see current state of x */
> smp_rmb();
> if (x == 0)
> do_something();
>
> The above situation is not acceptable?

Acceptable is just not the word. It plain doesn't work that way.

> Otherwise, we fail to be able to do_something() when it is perfectly
> fine to do so.

Can't be helped.


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