Re: Inconsistency in changing the state of task ??

Robert Love (rml@tech9.net)
06 Mar 2003 15:05:39 -0500


On Thu, 2003-03-06 at 08:11, prash_t@softhome.net wrote:

> Thanks Robert for the reply.
> But I notice that __set_current_state() is same as current->state. So, I
> didn't understand the safety factor on using __set_current_state( ).

There is no safety with __set_current_state(). It is just an
abstraction.

The safety comes from set_current_state(), which ensures memory
ordering.

This is an issue not just on SMP, but on a weakly ordered processor like
Alpha.

> Also why should I use __set_current_state() instead of set_current_state()
> when the later is SMP safe.

You only use __set_current_state() if you know you do not need to ensure
memory ordering constraints.

Robert Love

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