Re: [RFC PATCH] introduce sys_membarrier(): process-wide memorybarrier

[Paul E. McKenney]

On Fri, Jan 08, 2010 at 06:53:38PM -0500, Mathieu Desnoyers wrote:
> * Steven Rostedt (rostedt@xxxxxxxxxxx) wrote:
> > Well, if we just grab the task_rq(task)->lock here, then we should be
> > OK? We would guarantee that curr is either the task we want or not.
> 
> Hrm, I just tested it, and there seems to be a significant performance
> penality involved with taking these locks for each CPU, even with just 8
> cores. So if we can do without the locks, that would be preferred.

How significant?  Factor of two?  Two orders of magnitude?

							Thanx, Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/